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Presentasi berjudul: "PENTINGNYA SILIKAT BAGI TANAMAN TEBU Diabstraksikan: Smno.jursntnh.fpub.jan2013."— Transcript presentasi:

1 PENTINGNYA SILIKAT BAGI TANAMAN TEBU Diabstraksikan: Smno.jursntnh.fpub.jan2013

2 APLIKASI SILIKAT PADA TEBU Aplikasi Si dilakukan dengan dosis 0, 55, 110 dan 165 kg ha-1 Si, bahan yang dipakai Ca-Mg silicate (262,1 g kg-1 Ca; 56,8 g kg-1 Mg; 108,4 g kg-1 Si), diaplikasikan dalam larikan pada saat tanam. Hasil tanaman terbaik dicapai pada dosis 103,2 kg ha- 1 Si (952 kg ha-1 silicate). Aplikasi silikat meningkatkan kandungan Si-tersedia dalam tanah, yaitu ekstraksi 0.5 mol L-1acetic acid dan 0.01 mol L-1 CaCl2. Konsentrasi Si dalam daun tebu ditentukan oleh kultivar nya (A =3 g kg-1; B =2.18g kg-1). Dalam batang tebu, ternyata biomasa dan seapan Si terbaik diperoleh pada aplikasi dengan dosis 89 kg ha- 1 Si, tidak ada efek pada keruskaan akibat penggerek batang.

3 Rancangan Percobaan Aplikasi Si The experiment was set up in a completely randomized factorial scheme with four silicon rates (0, 55, 110 and 165 kg ha-1 Si), two cultivars (IAC and SP ), and 4 replications. The source of silicon was Ca-Mg silicate containing g kg-1 Ca; 56.8 g kg-1 Mg; g kg-1 Si. All plots received the same Ca and Mg quantities with additions of dolomitic lime (320g kg-1 Ca, 29.5 g kg-1 Mg) and/or MgCl2 (11.9% Mg) when necessary. The cultivars were chosen based upon yield potential, precocity, good number of sprouts under sugarcane mulch residue and differences on stalk borer tolerance (Diatraea saccharalis): low tolerance (SP ; Coopersucar) and intermediate tolerance (IAC ; Landell et al., 1997). Added Si as calcium magnesium silicate increased the amounts of extractable Si in a Quartzapsament soil, as well as increasing the yield and Si uptake in stalks of cultivar SP Rates of 103 kg ha-1 Si and 89 kg ha-1 Si provided the best yield and absorption of silicon of SP , respectively, but it did not promote less stalk borer damage.

4 Pentingnya Si bagi Tebu Silicon fertilization has been shown to improve chlorophyll and structure of leaves, reduce lodging, and minimize biotic and abiotic stress, but there is little information in Brazil, the major world sugarcane producer. Positive results have been obtained with silicon application in many countries, including Brazil (Berthelsen et al., 2002; Kingston et al., 2005; Elawad et al., 1982; Korndörfer et al., 2000; Brassioli et al., 2009). Most of these results were not exclusive from silicon because the high rates of silicate can improve pH, Ca, and Mg contents (Alcarde, 1992). The silicate fertilization applied in furrow planting could be useful to reduce the cost of this product used in rates similar to lime (>2 or 3 t ha-1) and study the direct effects of Si on sugarcane. Another beneficial advantage of silicon to sugarcane is the possibility of reducing damage of insects. Studies conducted in pots and field conditions with Si has shown positive effects to control of African stalk borer Eldana saccharina. Stalk borer (Diatraea saccharalis) is a problem in Brazil controlled by biological methods and/or resistent cultivars. Good characteristics in sugarcane such as low fiber and high sugar are generally related to stalk borer tolerance. An increase of silicon uptake in sugarcane with silicate applications could reduce the damage of ‘brazilian’ stalk borer.

5 Hubungan antara Si-tanah yang terekstraks 0.5 mol L-1 acetic acid dan 0.01 mol L-1 CaCl2 ( kedalaman contoh tanah 0-25cm dan cm) dengan serapan Si batang tebu dengan dosis Ca-Mg silicate.

6 Si PADA DAUN TEBU The variability of silicon absorption in sugarcane cultivars can be associate with its yield and sugarcane borer (D. saccharalis) incidence. The objective of this work was to evaluate silicon uptake by the leaves and accumulation in total aerial plant and its relationship to yield, quality and stalk borer in sugarcane cultivars. Yields were superior to 100 t ha -1 at 16 months of age and IAC and RB cultivars showed the highest diameter and height, respectively. The IAC showed the highest values of sugar and lowest to fiber content. Silicon content in leaves collected at 6 months showed not significant differences. The IACSP , IACSP and IAC showed the highest silicon content in the leaves at 8 months and they were superior to 10 g kg -1 Si. Higher silicon content in the leaves was found for IAC at 10, 14 and 16 months and, in bagasse, to RB at 10 and 12 months. The foliar analysis collected at 8 months and the total aerial plant, collected just before harvest, were efficient to show differences on silicon uptake among cultivars. There was no relationship among Si uptake and yield and borer stalk incidence, which was reduced with increase of fiber content. Sumber: Bragantia vol.69 no.4 Campinas Dec. 2010

7 Beberapa jenis tanah di perkebunan tebu telah lama sekali digunakan untuk budidaya tebu, beberapa tanah mempunyai kandungan Si-tersedia yang rendah. The objectives were to evaluate silicon availability in soils and the relationship between availability and uptake. Therefore, we assessed the dry matter yields of sugarcane cultivated in three soil types, with and without silicon fertilization. The experiment was set up in a completely randomized factorial scheme (4 x 3 x 2) with four silicon rates (0, 185, 370 and 555 kg ha-1 Si) as Ca-Mg silicate and three soils: Quartzipsamment (RQ), Rhodic Hapludox (LV) and Rhodic Acrudox (LVdf), in four repetitions. All plots (100 L) received same Ca and Mg quantities with additions of dolomitic lime and or MgCl2. The LVdf soil showed the higher soluble silicon concentration, followed by LV and RQ. Added Si applied increased the amounts of soluble content in all soils but Si uptake in leaves of sugarcane were just increased to RQ and LV. However, addition of Si to the soils did not promote changes in dry matter yields and Si uptake on stalks of sugarcane. Sumber: The Proceedings of the International Plant Nutrition Colloquium XVI, Department of Plant Sciences, UC Davis, UC Davis

8 Si bagi Tebu Silicon is not an essential element (Epstein, 1999), but its fertilization to Si accumulating plants, such as sugarcane, could exhibit increased yields (Fox et al., 1967, Elawad et al.,1992; Anderson et al.,1991; Korndörfer et al., 2002). Soils cultivated with sugarcane were classified in four groups (Berthelsen et al.2002) as a function of the amount of soluble Si in CaCl Mol L-1 (mg kg-1 Si): very low (0-5), low (5-10), limited (10-20), and sufficient (20 to >50). Several classes of soils in Brazil are classified as low silicon content (Korndörfer et al., 2002) and these soils are cultivated with sugarcane.

9 Concentration uptake in leaves and stalks after harvest of sugarcane and soluble silicon in soils with silicon (*p<0.05). (Sumber: Silicon absorption by sugarcane: effect of soils type and silicate fertilization. The Proceedings of the International Plant Nutrition Colloquium XVI, Department of Plant Sciences, UC Davis, UC Davis

10 APLIKASI Si: EFEK FISIK DAN FISIOLOGIS Silicon is an integral part of cell walls, and has a similar role to lignin, in that it provides compression-resistance and rigidity in cell walls, thus providing structural strength to the plant. An ample supply of Si has been reported to reduce lodging (drooping, leaning or becoming prostrate) in grass crops due to improved mechanical strength. The improved rigidity of the cell walls also promotes a more erect habit and disposition of the leaves, resulting in better light interception and photosynthetic efficiency. Sugarcane cultivars high in Si may also show enhanced sucrose synthesis, due to improved photosynthesis, as shoots are not as likely to become prostrate following wind and rain. Sumber: Sugar Research and Development Corporation Final Report. SRDC Project CLW009. CSIRO 2003

11 Varieties have changed substantially between 1970 and 1990, and lodging, once a factor selected against, is now considered a less important selection criterion, with the use of mechanical chopper harvesters. Consequently, plant-breeding programmes may have been inadvertently selecting varieties with lower concentrations of Si in the stalk. As there is evidence that lodging can result in loss of cane yield and reduction in sugar content, this highlights the possibility that low plant and soil Si levels may be a causal factor in declining sugarcane yields observed over recent years. Adequate Si nutrition may also assist crops withstand the effects of drought conditions in areas reliant on rainfall, or declining water quality in irrigation areas. Plants with a well-thickened layer of Si associated with the cellulose in cell walls of epidermal cells have been observed to be less prone to wilting and have improved drought resistance. Silicon may also reduced stress to salt in a similar way that it alleviates water stress. Work with cereal crops suggest that Si can both increase photosynthesis and decrease the permeability of plasma membranes of leaves of salt-stressed plants. In addition, Si has been shown to inhibit the uptake of Na and increase the uptake of K, thus alleviating the effect of salt toxicity and improving vegetative growth.

12 Ketahanan thd Stress Biotik Improved resistance to disease and pathogenic fungal attack, due to Si applications, has been reported for a number of crops. It is generally agreed that as most parasitic fungi penetrate the host by boring through the epidermal cell wall, Si in these walls may act as a mechanical barrier. In addition, Si may also protect the plant by its association with the cell wall constituents, minimizing the enzymatic degradation that accompanies the penetration of the cell wall by the fungal hyphae. The highly silicified leaves of grasses can not only make the plant more resistant to attack by pathogenic fungi, but also to attack by predaceous chewing insects, as they can suffer a high mortality when their mandibles and maxillae become worn down, rendering their mouthparts ineffective. It is relevant, therefore, that recent history of yield decline in sugarcane dates back to the recognition of ‘Northern Poor Root Syndrome’ (NPRS) as a problem in sugarcane on Queensland’s wet tropical coast (Egan et al., 1984). Although, it has been suggested that the build-up and susceptibility to root pathogens may be the ultimate expression of other factors being out of balance in the farming system, it is plausible that low soil and plant Si levels have allowed increased susceptibility to pathogen attack.

13 Ketahanan thd stress Abiotik Adequate Si nutrition is reported to have a major effect on the absorption and translocation of some macronutrient and micronutrient elements, assist in the negative effects resulting from nutrient imbalances, and also have the ability to alleviate, or in some cases to eliminate, the adverse effects of heavy metals, excess phosphorus and salinity. Current sugarcane production systems often apply nitrogen at rates far in excess of what may be considered necessary for maximum yield, and with high soil concentrations of phosphorus, may result in unbalanced nutrient supply on many sugarcane soils. That yield decline can be temporarily reversed by increasing N fertilizer rates to soil Si-depleted systems. However, for sustained yields, Si fertilisation is required to balance applied nutrients, particularly N, when high rates can result in increased problems with lodging. Although Si additions are reported to improve P nutrition, conversely, continued use of superphosphate may have also resulted in accelerated depletion of soil Si reserves, since P effectively competes with Si for specific sorption sites, thereby resulting in the loss of Si through leaching.

14 Si dalam Tanah Soil Si status, indicative of potential soil productivity Silicon is recognized as a major constituent of soils. It is present in the solid phase of soils as alumino-silicate clay minerals and crystalline minerals, and also in a number of amorphous forms such as plant phytoliths. In the soil solution, or liquid phase, Si is present as mono- and poly- silicic acids, and also present as complexes with inorganic and organic compounds. While it is the mono-silicic acid component that is taken up by plants and has a direct influence on crop growth, the poly-silicic acids, and probably the inorganic and organic Si complexes, are important as sources/sinks of Si which can replenish the soil solution following crop use, but importantly, they can have a significant effect on soil properties such as improving soil aggregation and increasing soil water holding capacity and also increasing the exchange and buffering capacity of soils. It has also been suggested that the organosilicic compounds play a specific role in organic matter formation.

15 Reaksi-reaksi Si dalam tanah

16 Ketersediaan Si dalam tanah In general, most soils have appreciable amount of be adequate for crop growth. Although quartz is a major source of Si in many soils, the rate of dissolution of this mineral is very slow and therefore does not contribute significantly to the labile pool of soluble Si. For plant growth the important forms of soil Si are the soluble forms, mainly monosilicic acid (Si(OH) 4 ), various polymers and silica gels, Si adsorbed onto sesquioxidic surfaces, and that present in crystalline and amorphous soil minerals. The quantity present in each of these forms is largely controlled by the dominant soil mineral and the amount of Si lost (desilication) through weathering. The solubility of Si in the soil is influenced by several factors including, particle size, soil pH, organic complexes, the presence of aluminium, iron and phosphate ions, temperature, exchangeable/dissolution reactions, and soil moisture.

17 APLIKASI BAHAN-BAHAN SILIKAT METODE APLIKASI Si Aplikasi kalsium-silikat pada pertanaman tebu dapat dilakukan dengan cara disebar dan kebudian dibenamkan ke tanah sebelum penanaman bibit.

18 Manfaat aplikasi pupuk silikat pada tanaman tebu: 1.Menetralisir kemasaman tanah: Ini akan memperbaiki aktivitas mikroba tanah dan ketersediaan N,P, S dari bahan organik tanah; mereduksi toksisitas Fe, Al, Mn dalam larutan tanah 2.Mensuplai unsur hara Ca, Si, P, K, Mg,S dan unsur mikro 3.Meningkatkan hasil tebu dan hasil gula: diameter dan panjang batang, jumlah batang, daun-hijau, ineks pertumbuhan 4.Memperbaiki fotosintesis dan produksi klorofil 5.Regulator ensim dalam sintesis gula, dan simpanan sukrose dalam tanaman 6.Mereduksi kerobohan tanaman, habit tumbuh tegak, sehingga efisien cahaya 7.Meningkatkan ketahanan tanaman terhadap gangguan hama dan penyakit 8.Mereduksi transpirasi sehingga air lebih efisien 9.Mereduksi toksisitas Mn dan mencegah akumulasi Mn di daun 10.Memperbaiki nutrisi P: Mereduksi fiksasi P, meningkatkan kelarutan P-tanah, efisiensi pemanfaatanP oleh tanaman 11.Memperbaiki kesuburan tanaman

19 Pangaruh dosis aplikasi Ca-silicate terhadap tinggi batang dan jumlah batang tebu

20 Pengaruh aplikasi Ca-silikat terhadap Konsentrasi Si (%) dalam daun muda yang telah mekar sempurna (TVD) pada tanaman umur 7 bulan; hasil batang tebu, ccs dan bobot segar umur 8 bulan setelah tanam; dan hasil akhir tebu, ccs dan hasil gula

21 Pengaruh aplikasi Ca-silikat terhadap kadar serat (%) batang tebu, persen daun yang terinfeksi penyakit karat-orange dan becak kuning pada umur 8 bulan setelah tanam

22 Pengaruh aplikasi Ca-silikat terhadap hasil tebu ratoon pertama, ratoon ke dua, tebu tanaman, dan kumulatifnya

23 Hubungan antara hasil relatif tebu dengan indeks ketersediaan Si-tanah (a) Si (sol) ekstraksi 0.01 M CaCl 2 (b) Si (ext) ekstraksi M H 2 SO 4.

24 Hubungan antara hasil relatif tebu dengan indeks ketersediaan Si-tanah (AEC / 100g clay) pada dua jenis tanah yang berbeda (a) Si (sol) dari ekstraksi 0.01 M CaCl 2 (b) Si (ext) dari ekstraksi M H 2 SO 4.

25 Pengaruh aplikasi calcium silicate terhadap tingkat hijauanya daun (SPAD units), tebu ratoon pertama dan ke dua.

26 Pengaruh aplikasi bahan silikat terhadap tingkat hijaunya daun (SPAD units) pada tanaman tebu

27 Reaksi-reaksi yang terjadi dalam tanah setelah aplikasi calcium silicate slag (Kato and Owa, 1997a).

28 Karena calcium silicate reaksinya lambat untuk menghasilkan asam mono-silikat (H 4 SiO 4 ) yang tersedia bagi tanaman (reaksi 1 - 4), Ca 2+ d an Ca(OH) 2 hasil dari reaksi akan diserap pada koloid tanah (reaksi 5 dan 6). Permukaan hidroksilasi pada permukaan tanah akan melepaskan proton, secara bertahap akan mengasamkan tanah. Kalau pH tanah menurun maka kelarutan Si dari terak kalsium silikat akan meningkat.

29 Reaksi kondensasi dan pengendapan polimer Si (Drees et al., 1989)

30 Flokulasi Si-polymorphs dengan pembentukan ion-ion hidroksida logam yang bermuatan positif (MOH+) (Drees et al., 1989).

31 Pengaruh aplikasi Ca-silikat terhadap KTK tanah permukaan 0-10cm, diukur setelah tanaman tebu (2000) dan setelah ratoon pertama (2001).

32 Hubungan antara hasil tebu (ton/ha) ratoon pertama dengan kadar Si (%) daun muda (TVD) tanaman tebu umur 7 bulan.

33 Si Memperbaiki Produksi Tebu Tebu sangat respons terhadap aplikasi bahan-bahan sumber silika. Aplikasi bahan-bahan silikat dengan dosis 0, 5, 10, 15, dan 20 metric tons/ha, brupa bahan-bahan TVA slag, Florida slag, dan Portland cement. Bahan-bahan silikat disebar di permukaan tanah dan dicampur rata dengan tanah menggunakan bajak “disc harrow”. Aplikasi silikat meningkatkan tinggi tanaman, diameter batang, jumlah batang, hasil tebu dan hasil gula, baik pada tanaman tebu maupun ratoonnya. Aplikasi bahan silikat sebanyak 15 metric tons/ha meningkatkan hasil tebu dan hasil gula masing-masing 68 dan 79% untuk tebu tanaman; sebesar 125 dan 129% pada tebu ratoon. Peranan vital Si dalam pertumbuhan tanaman tebu terbukti dengan meningkatnya ukuran tanaman dan jumlah anakan akibat aplikasi bahan silikat. Sumber: Agronomy Journal Vol. 74 No. 3, p

34 PENTINGNYA Si BAGI TEBU Silicon (Si) is one of the most abundant elements found in the earth's crust, but is mostly inert and only slightly soluble. Agriculture activity tends to remove large quantities of Si from soil. Sugarcane is known to absorb more Si than any other mineral nutrient, accumulating approximately 380 kg ha-1 of Si, in a 12-month old crop. Sugarcane (plant growth and development) responses to silicon fertilization have been documented in some areas of the world, and applications on commercial fields are routine in certain areas. The reason for this plant response or yield increase is not fully understood, but several mechanisms have been proposed. Some studies indicate that sugarcane yield responses to silicon may be associated with induced resistance to biotic and abiotic stresses, such as disease and pest resistance, Al, Mn and Fe toxicity alleviation, increased P availability, reduced lodging, improved leaf and stalk erectness, freeze resistance, and improvement in plant water economy. Sumber: J. Plant Nutr. 22 (12):

35 FUNGSI Si BAGI TANAMAN Tanaman tebu mengakumulasikan sejumlah besar Si dalam bentuk silica gel (SiO2.nH2O) yang dilokalisir dalam tipe-tipe sel tertentu. Fungsi Si dalam tanaman tebu adalah: i) Memperkuat dinding sel (ketahanan terhadap lodging); ii) Ketahanan terhadap hama dan penyakit; iii) Reduksi evapotranspirasi; iv) Reduksi toksisitas logam berat v) Unsur esensial bagi pertumbuhan tanaman normal. PEMUPUKAN Si Kajian-kajian tentang hara Si pada tanaman tebu telah banyak dilaporkan di Australia, South Africa, Brazil, Taiwan, India, Mauritius, Puerto Rico, the United States dan negara-negara lain produsen tebu. Pemupukan Si juga telah dipraktekkan untuk memperbaiki produktivitas tebu di berbagai perkebunan tebu di dunia. Efisiensi pemupukan Si ternyata sangat ditentukan oleh karakteristik fisika dan kimia bahan pupuk-silikat ; teknologi aplikasinya, waktu aplikasinya dan dosis aplikasinya.

36 SERAPAN Si TANAMAN TEBU Sugarcane absorbs large amounts of Si from soil. According to Samuels (1969), at 12-months the above ground parts contained 379 kg ha-1 of Si, compared with 362 kg ha-1 of K and 140 kg ha-1 of N. Ross et al. (1974) reported the removal of 408 kg ha-1 of total Si from soil by a sugarcane crop (tops + millable cane) yielding of 74 t ha-1. The removal of Si from soil could be more important in intensively cultivated areas. As a result of the Si export of this magnitude, a temporary depletion of bio-available Si in soils could also be a possible factor of declining yields of ratoon crops. In other words, there may be an apparent need for consideration of Si nutrient management in developing appropriate integrated nutrient management system for sustainable sugarcane production, especially in certain ecoregions having Si deficient weathered soils and organic soils.

37 NUTRISI SILICON TANAMAN TEBU There is ample evidence that different species uptake greatly different amounts of Si. Legumes and other dicotyledons have much lower levels than monocotyledons, for example, the Gramineae. Sugarcane is a Si accumulator plant, which strongly responds to Si supply. The Si form that which sugarcane usually absorbs has no electric charge (H4SiO4) and is not very mobile in the plant. Because the uptake of undissociated H4SiO4 may be nonselective and energetically passive, and its transport from root to shoot is in the transpiration stream in the xylem, the assumption has sometimes been made that the movement of Si follows that of water (Jones and Handreck, 1965). The silicic acid is deposited mainly in the walls of epidermal cells, where it is integrated firmly into the structural matter and contributes substantially to the strength of the stem. The distribution of Si within the shoot and shoot parts is determined by the transpiration rate of the part (Jones and Handreck, 1967). Most of the Si remains in the apoplasm mainly in the outer walls of the epidermal cells on both surfaces of the leaves as well as in the inflorescence bracts of graminaceous species and is deposited after water evaporation at the end of the transpiration stream, (Hodson and Sangster, 1989). Silicon is deposited either as amorphous b (SiO2. hH2O, 'opal') or as socalled opal phytoliths with distinct threedimensional shapes (Parry and Smithson, 1964). The preferential deposition of Si in the apoplasm of epidermal cells and trichomes is reflected in similarities between surface features of leaf and structure of Si deposits (Lanning and Eleuterius, 1989). The epidermal cell walls are impregnated with a firm layer of Si and become effective barriers against both fungal infections and water loss by cuticular transpiration. Despite that, there is increasing evidence for the necessity to modify the traditional view of Si deposition in the cell walls as a purely physical process leading to mechanical stabilization (rigidity) of the tissue and acting as a mechanical barrier to pathogens. Silicon may be involved in cell elongation and/or cell division. In a field study, plant crop height was quadratically related to the rate of Si applied, while plant crop stem diameter was linearly related (Elawad et al., 1982a). Gascho (1978) reported that application of TVA slag and Na silicate to greenhouse grown sugarcane increased plant height. Phicket (1971) indicated that some of the effects of Si on sugarcane were longer stalks with larger diameters and increased number of suckers. These observations on cane and observations for other crops suggest a possible role of Si in cell elongation and/or cell division (Elawad et al., 1982ab). Ayres (1966) determined that only 15% of the total plant Si are present in sugarcane stalks at 14 months. The leaf sheaths on the best cane-growing soils contained about 2.5 percent Si. Using the sixth leaf sheath, Halais (1967) suggested critical levels of 1.25 percent of Si and 125 mg dm-3 of Mn. If the Si level was below this value, Si responses could be expected. Under field conditions, in Florida, Anderson (1991) suggested that at least 1% Si (~2.1 % SiO2 in the leaf dry matter) is required for optimal cane yield. At 0.25% Si the yield drops to about 50%. According to Rodrigues (1997), increasing Si rate from 0 to 924 kg ha-1 using Wollastonite, resulted in substantial increase of the Si content in the leaves from 0.7 to 1.93 % and Si in the soil from 14 to 46 mg dm-3 (TABLE 2). Better Si-accumulating cultivars may have the advantage of requiring lower rates of Si fertilizer or less frequent applications. A relatively narrow base of sugarcane germplasm demonstrated significant variability for Si content in leaf tissue (Deren et al., 1993). Korndörfer et al. (1998a) also found that sugarcane cultivars have different capacities to accumulate Si in the leaves. The Si levels in the leaf were of 0.76, 1.04 and 1.14% respectively for the cultivars: RB72454, SP and SP

38 Si DAN PENINGKATAN HASIL TANAMAN Research work demonstrating the use of silicate slag as a source of Si for sugarcane has been largely conducted in Hawaii, Mauritius, and Florida. Yield responses are great enough that sugarcane grown in the Everglades (South Florida) is routinely fertilized with calcium silicate when soil tests indicate the need. However, Si fertilization requires large quantities of slag (generally 5 Mg ha-1), making it quite costly (Alvarez et al., 1988). Yields of cane and sugar in Hawaii have been increased 10-50% on soils low in Si, and many sugar plantations regularly apply calcium silicate in responsive fields (Ayres, 1966; Clements, 1965a; Fox et al., 1967b). Increased yields of sugarcane in fields have been reported in Mauritius (Ross, 1974) and Puerto Rico (Samuels, 1969); while in South Africa (Preez, 1970) and Brazil (Gascho and Korndörfer, 1998), several sources of silicate increased sugarcane yields in pots.

39 Si DAN KONTROL PENYAKIT In sugarcane, small rust-colored or brownish spots on the leaves of cane growing on highly weathered soils characterize a leaf disorder called freckling. In severe cases, affected lower leaves may die prematurely and can affect cane yield. Freckled plants are less efficient in performing photosynthesis not only because they have less leaf but also because many leaves are freckled. This leaf disorder was corrected by application of silicate materials (Clements, 1965b). Ayres (1966), Fox et al. (1967b), and Wong You Cheong et al. (1972) have also noticed that leaf freckling symptoms in sugarcane were gone following Si treatments. Elawad et al. (1982a) observed significant decrease in percent freckling in the plant crop as well as the ratoon crop with application of 20 t ha-1 of TVA slag to muck soil. The mechanism for the disappearance of leaf freckling in sugarcane following Si application is still not well understood. Clements et al. (1974) attributed leaf freckling mainly to the presence of toxic levels of Fe, Al, Mn and Zn in the soil solution. However, Gascho (1978) stated that the development of freckled leaves is an expression of the plant's need for Si. Silicon deposited in the epidermal tissue mechanically deters hyphae invasion (Takahashi, 1996). Furthermore, Si physiologically promotes ammonium assimilation and restrains the increase in soluble nitrogen compounds, including amino acids and amide, which are instrumental for the propagation of hyphae (Takahashi, 1996). Recently, Raid et al. (1992) investigated the influence of cultivar and soil amendment with calcium silicate slag on foliar disease development in sugarcane hybrids (TABLE 6). Severity of sugarcane rust (Puccinia melanocephala H. Syd. and P. Syd) was not affected by application of silicate slag. However, they noticed significant reduction in severity of ringspot with the addition of the slag (Leptosphaeria sacchari Breda de Hann) by an average of 67% across the five cultivars studied. Silicon is known to be deposited at the external surface of cell walls of plants, thus forming a mechanical barrier to penetration of the pathogen causing ringspot but not to that of rust in sugarcane (Kunoh, 1990; Raid et al., 1992). A hypothesis has been presented that the polymerized Si acids fill up apertures of cellulose micelle constituting cell walls and make up a Si cellulose membrane. This membrane is supposed to be mainly responsible for protecting the plant from some diseases and insects (Yoshida et al., 1969)

40 Si DAN PENGENDALIAN HAMA While studying the influence of UVB radiation and soluble Si on growth of sugarcane, Elawad et al. (1985) additionally observed increased resistance of sugarcane to stem borer (Diatraea saccharalis F.) with improved Si nutrition. Newly hatched D. saccharalis larvae, when starting their attacks on sugarcane plants, do so by feeding on epidermal tissue of the sheath, leaves and developing internodes in the immature top of the plants. The presence of Si crystals in these tissues should hinder the feeding of the insect, which in this phase has rather fragile mandibles. Plants like sugarcane and rice, with high Si contents, seem to interfere in the feeding of larvae, damaging their mandibles. It is possible that plants with higher Si contents in their tissue would have a higher level of resistance to the infections by such pests. The high Si levels in Na2SiO3 treated plants may have served as a deterrent to the borers. A significant negative relation was observed between leaf Si content and shoot borer incidence. Sugarcane varieties with a higher number of Si cells per unit area in the leaf sheath portion 5 to 7 cm from the base were found resistant to the shoot borer. The percentage of the incidence of borer damage was less in sugarcane (var. GPB 5) treated with bagasse furnace ash and silicate slag than in untreated sugarcane. It is interesting to note that increased application of N fertilizers alone increased the incidence of sugarcane stalk borer, and that of another borer (Chilo auricilius Dudgeon) in India. The increase of the borer’s incidence may be partly due to the formation of softer stalks resulting from the lower than adequate levels of plant Si required for strengthening of the stalk cells. In other words, the borer incidence could have been prevented by application of Si together with N fertilizers.

41 Si MEMPERBAIKI EKONOMI AIR Water stress under field conditions is common and affects cane yields. Improved Si nutrition may reduce excessive leaf transpiration. One of the symptoms associated with Si deficiency is the excessive rate of transpiration. The rate of transpiration of Si deficient plants increased by about 30% over the rate of control plants (rates were measured as grams of water lost through transpiration per gram of dry weight per day). Okuda and Takahashi (1965) obtained a similar result, but found that in barley the effect was small (less than a 10% difference between Sideficient and control plants). This observation suggests a role for Si in the water economy of the plant. An increased rate of transpiration in Si-deficient plants could explain the wilting that may occur, particularly under conditions of low humidity, and could also help to explain the increased accumulation of Mn and other mineral nutrients in the aerial parts of Si deficient plants. The rate of transpiration is presumably influenced by the amount of silica gel associated with the cellulose in the cell walls of epidermal cells. Hence, a well thickened layer of silica gel should help to retard water loss, while epidermal cell wall with less silica gel will allow water to escape at an accelerated rate. Since this role of Si nutrition may result in water economy and may be important in water management, field research on this potential beneficial has merit.

42 Si MEREDUKSI KEROBOHAN DAN MEMPERBAIKI KETEGAPAN TEBU One other effect of increased plant Si content, which has been reported in literature, is the increased mechanical strength of plant tissue, which results in reduced lodging. Under field conditions, particularly in dense stands of sugarcane, Si can stimulate growth and yield by decreasing mutual shading by improving leaf erectness, which decreases susceptibility to lodging. Leaf erectness is an important factor affecting light interception in dense plant population and, hence, photosynthesis. In rice, Si supply increased the photo-assimilation of carbon, especially after heading, and promoted the translocation of assimilated carbon to the leaves. This effect of Si on leaf erectness is mainly a function of the Si depositions in the epidermal layers of the leaf panicle.

43 INVERSI SUKROSE Few investigations of the role of Si in sugarcane have considered the mechanism by which it affects sugarcane tonnage production. However, Alexander et al. (1971) has undertaken the task of finding the role that Si plays in the synthesis, storage and retention of sucrose in the sugarcane plant. He found that sucrose inversion in sugarcane juice samples was delayed for several days by adding sodium metasilicate immediately after milling. Chromatographic evidence suggests that at low levels metasilicate forms a physical complex with sucrose which prevents the union of invertase with its substrate. The hypothetical fructose-silicate configuration is retained even after sucrose is inverted, thereby preventing fructose from being metabolized by microorganisms. Fructose appears to be the preferential hexose for microbial growth, i.e. most suitable carbon source. The effective preservation of fructose by silicates may constitute a bacterial repression operating in addition to the invertase-inhibitory action. Next to K, Si is the most extensive constituent of ash in sugarcane juice. It is the highest component of millable stalks ash and represents an even greater percentage in leaves. However, silicates in cane are believed to be one of the major contributors to mill roll wear.

44 BAHAN SUMBER SILIKAT The usual carrier for Si is calcium silicate and this material can also supply Ca to a Ca-deficient soil. The Hawaiian Cement Corp. first manufactured calcium silicate in August Gascho and Korndörfer (1998) working with four different soils groups from Brazil and several Si sources (Wollastonite, thermal-phosphate, calcium silicate and basic slag) concluded that thermal-phosphate was the most effective source to supply both Si and P to the rice plant. In several studies, no attempt was made to maintain constant Ca levels with increasing calcium silicate applications. It is important to separate Si from Ca effects. Ayres (1966) reasoned that since both calcium silicate and calcium carbonate treatments had increased yields, the calcium supply probably was not the factor causing higher yields in their studies. Teranishi (1968) concluded that yield increases from calcium silicate applications could not be attributed to Ca supply in his experiment since plant Ca was above the critical level for sugarcane and also since calcium carbonate had been added to the zero Si plots to maintain pH and supply adequate Ca. According to Ross et al. (1974), calcium silicate applied to low Si soils at planting increase annual cane yield over a 6 year cycle (TABLE 4) and well demonstrated the residual effect from this source. For research purposes, many different Si sources have been tested: Wollastonite (CaSiO3), cement kiln fired (fused) calcium silicate, Portland cement (9 to 23 % Si), di-calcium ortho- silicate (Ca2SiO4), calcium metasilicate, minigranulated calcium metasilicate, electric furnace slag (by-product of furnace production of elemental P), blast furnace slag, basic slag, Thomas slag, mill furnace ashes, crushed basalt, volcanic cinder, and others (Rozeff, 1992abc) (TABLE 9)

45 KALSIUM METASILIKAT Calcium metasilicate was generally much more soluble and readily available to sugarcane than calcium ortho- silicate. Mini-granules of calcium metasilicate, which were small, spherical (50 to 150 mesh) made from fine (100 to 200 mesh) material using 2% sodium oxide as a binder, were agronomically equivalent to fine ungranulated calcium metasilicate (HSPA, 1982). A fine grade of Si fertilizer was best for increasing Si content and grain yield. Rice yields increased relative to the control by 20-26%, 18%, and 4-11% for the fine, standard, and pelletized forms, respectively in 1990/1991. Agronomic feasibility of mini-granulation of CaSiO3 has been confirmed. When containing high amounts of Si, both granular and powered slag are equally efficient. These are useful findings because they offer potential the option of mini-granulation of fine silicate sources for solving their handling problem.

46 DOSIS APLIKASI SILIKAT Dosis aplikasi Si sangat dipengaruhi oleh komposisi kimiawi dari sumber Si, kandungan Si-tersedia dalam tanah, dan kandungan Si dalam tanaman. Rekomendasi aplikasi silikat tanaman tebu di Hawaii 7.5 tons ha-1 bahan terak TVA (Tennessee Valley Authority). Rekomendasi lainnya adalah 4.94 t ha-1 calcium metasilicate (CaSiO3). Rekomendasi untuk tebu ratoon t ha-1 CaSiO3, kalau kandungsn Si dalam tanah kg ha-1.

47 WAKTU DAN FREKUENSI APLIKASI SILIKAT Umumnya aplikasi Si dilakukan ke tanah sebelum penanaman bibit. Pengalaman petani tebu di Florida, kalau respon terhadap bahan Si dapat diperoleh pada aplikasi tahun pertama, maka tidak perlu aplikasi Si lagi paling tidak selama empat tahun. Dalam sistem rotasi / pergiliran tanaman padi dengan tebu, aplikasi terak-silikat sebelum tanaman tebu, dan sebelum tanaman padi dalam rotasinya dengan tebu, menunjukkan respon agronomis yang bagus. Pengalaman menunjukkan bahwa aplikasi terak-silikat yang lebih menguntungkan adalah sebelum tanaman padi dalam sistem rotasi padi – tebu.

48 UKURAN PARTIKEL BAHAN SILIKAT The particle size of the Si fertilizer is important in increasing Si content of leaves and subsequent disease control. Particle size is associated with increased surface area; consequently, the distribution and dissolution of smaller Si particles mixed in the soil is enhanced and the probability of root particle contact is increased. Combining fine particles into pellets probably results in less Si-soil contact, leading to reduce Si availability to the crop, although some particle degradation could occur during soil incorporation. The particle should be of a size and well mixed with the soil. If very fine, Si sources create dusty conditions and can adversely affect material handling and application performance in the field. Special precautions are necessary for avoiding exposure of workers to the dust. This dust problem may limit the use of silicate slag for sugarcane in developing countries where it will be mainly applied manually. Mini-granulation of fine calcium silicate materials seems to a potential alternative for addressing the dust problem. Small particle size increases the effectiveness of silicate materials. Harada (1965) called attention to the superiority of finely ground TVA slag compared with coarsely ground, 16 mesh (<1.6 mm) material.

49 Soil silicon amendments increase resistance of sugarcane to stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae) under field conditions Malcolm G. KeepingMalcolm G. Keeping, Jan H. Meyer, Chandani SewpersadJan H. Meyer Plant and Soil. February 2013, Volume 363, Issue 1-2, pp Issue 1-2 Soil amendment with silicon (Si) can significantly increase resistance of susceptible sugarcane cultivars grown in pots to stalk borer Eldana saccharina (Lepidoptera: Pyralidae). This study tested the hypothesis that a single application of silicate can increase resistance to E. saccharina and increase yield in field- grown sugarcane. Two Si materials (Calmasil® and Slagment® at 4 and 8 t/ha) were applied at planting to a field trial extending over three successive crops and incorporating three sugarcane cultivars varying in borer susceptibility. Both materials, especially Slagment, significantly increased soil, leaf and stalk Si content, but leaf Si levels seldom exceeded 0.5 %. Silicon treatment significantly reduced percent stalks bored in all three crops and stalk length bored in the second ratoon crop, but did not affect borer numbers per 100 stalks (E/100) or increase cane or sucrose yield. Borer damage and E/100 were significantly and consistently reduced in the resistant cultivar. We argue that if leaf Si% in field sugarcane can be elevated to or exceed 0.8 %, using materials that release Si slowly, substantial reductions in stalk damage and sucrose loss could be achieved in susceptible cultivars in low-Si soils. Diunduh dari: 4jan2013

50 Silicon impedes stalk penetration by the borer Eldana saccharina in sugarcane Kvedaras OL, Keeping MG Entomologia Experimentalis et Applicata [2007, 125(1): ] Many plants grown in soils amended with silicon (Si) display increased levels of resistance to attack by insect herbivores. This study aimed to determine if Si treatment impeded Eldana saccharina Walker (Lepidoptera: Pyralidae) stalk penetration and subsequent damage, as well as borer mass gain, on the node and internode of a susceptible (N11) and a resistant (N33) sugarcane cultivar. Sugarcane [Saccharum spp. (Poaceae)] cultivars were grown in a pot trial in Si-deficient river sand, with (Si+) and without (Si-) calcium silicate. Sugarcane was infested with 2-week-old E. saccharina larvae and harvested at four times, 24, 48, 72, and 96 h after infestation. Silicon-treated plants showed significant increases in Si content compared to controls, and the external rind was significantly harder for Si+ cane than Si- cane.Eldana saccharinaLepidopteraN33sugarcaneSugarcanePoaceaeSi+Si-silicate rindSi+Si- Silicon treatment significantly decreased borer penetration, stalk damage, and larval mass gain. The results are consistent with the hypothesis that Si contributes to sugarcane stalk borer resistance by impeding larval penetration. Silicon appears to contribute to the suppression of E. saccharina directly through reduced larval growth and feeding damage to the crop, and indirectly by delaying stalk penetration, resulting most likely in increased exposure time of young larvae to natural enemies, adverse climatic factors, or control measures that target young larvae (e.g., insecticides). Diunduh dari: 4jan2013

51 Calcium silicate enhances resistance of sugarcane to the African stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae) M. G. Keeping, J. H. Meyer Agricultural and Forest Entomology. Volume 4, Issue 4, pages 265–274, November 2002Volume 4, Issue 4, The stalk borer Eldana saccharina is the most destructive pest in sugarcane in South Africa. This study investigated: (1) the potential of applied silicon in enhancing plant resistance of sugarcane to E. saccharina, using calcium silicate as a carrier; (2) whether there was any interaction between cane variety (and stalk borer resistance) and silicon treatment. Six commercial varieties of sugarcane were treated in a pot-plant trial with two levels (5000 and kg/ha) of calcium silicate. After artificial infestation with E. saccharina, response to the treatments was assessed in terms of borer numbers and mass, and stalk damage. Calcium silicate significantly enhanced resistance at the higher rate compared with the control. Borer mass was reduced by 19.8% and stalk length bored by 24.4%. Lower treatment values were intermediate between those of the higher treatment and the control. The interaction between variety and Si treatment was not significant when varieties were examined individually in the analysis. However, the interaction was significant for borer mass when varieties were grouped according to their resistance characteristics. Susceptible varieties might benefit more from treatment with silicon than resistant ones, as resistant varieties showed no significant effect of silicon. All varieties had increased silicon content due to the treatments, but differed appreciably in stalk silicon content at the different treatment levels. Similarly, within varieties, stalk silicon content did not correspond consistently with borer response patterns and silicate application rates. Diunduh dari: x/full……… 4jan2013

52 . Role of silica in resistance to Asiatic rice borer, Chilo suppressalis, in rice varieties Djamin, Arifin; Pathak, M. D. Journal of Economic Entomology (1967), 60(2), This study was conducted to test the reactions of several rice varieties to Asiatic rice borer infestation under natural field conditions, and to exam. the relation between plant silica content and susceptibility to stem borer. Based on results from 3 different tests, the varieties could be classified into 3 groups: resistant, moderately resistant, and susceptible. Reactions to the Asiatic rice borer infestation were highly consistent, indicating that resistance was due to inherent varietal characters. A highly significant neg. correlation was recorded between silica content of the stem and susceptibility to the rice borer. High silica content in the plant seemed to interfere with feeding and boring of the larvae and could cause defacing of their mandibles. Although several studies have reported the effects of silica on rice borer susceptibility, this is the first report of varietal difference in plant silica content. The use of varieties with high silica content is a more practical and economical method of reducing rice borer infestation than applying silicate to paddy soil. Diunduh dari: bin/sdcgi?APP=ftslink&action=reflink&origin=wiley&version=1.0&coi=1%3ACA S%3A528%3ADyaF2sXhtVChu7o%3D&md5=5c30035c680b0d211a eade5b0 ……… 4jan2013

53 . Silicon nutrition and sugarcane production: a review Savant, Narayan K.; Korndorfer, Gaspar H.; Datnoff, Lawrence E.; Snyder, George H. Journal of Plant Nutrition (1999), 22(12), A review with many refs. Silicon (Si) is one of the most abundant elements found in the earth's crust, but is mostly inert and only slightly soluble Agriculture activity tends to remove large quantities of Si from soil. Sugarcane is known to absorb more Si than any other mineral nutrient, accumulating approx. 380 kg ha-1 of Si, in a 12-mo-old crop. Sugarcane (plant growth and development) responses to silicon fertilization have been documented in some areas of the world, and applications on com. fields are routine in certain areas. The reason for this plant response or yield increase is not fully understood, but several mechanisms have been proposed. Some studies indicate that sugarcane yield responses to silicon may be associated with induced resistance to biotic and abiotic stresses, such as disease and pest resistance, Al, Mn, and Fe toxicity alleviation, increased P availability, reduced lodging, improved leaf and stalk erectness, freeze resistance, and improvement in plant water economy. This review covers the relationship of silicon to sugarcane crop production, including recommendations on how to best manage silicon in soils and plants, silicon interactions with others elements, and laboratory methodol. for determining silicon in the soil, plant and fertilizer. In addition, a future research agenda for silicon in sugarcane is proposed. Diunduh dari: bin/sdcgi?APP=ftslink&action=reflink&origin=wiley&version=1.0&coi=1%3ACA S%3A528%3ADyaK1MXntlOqsrs%3D&md5=dcfbf4a8de835d0b01930b c b……… 4jan2013

54 Multi-year response of sugarcane to calcium silicate slag on Everglades Histosols Anderson, D. L.; Snyder, G. H.; Martin, F. G. Agronomy Journal (1991), 83(5), The objective of this study was to determine the long-term response of sugarcane (Saccharum spp.) grown on a Terra Ceia muck (euic, hyperthermic Typic Medisaprist) at 2 locations in the Everglades Agricultural Area to slag applied (0, 2.5, 5, 10, 20 Mg ha-1) before either a rice (Oryza sativa)/sugarcane rotation or immediately before sugarcane. Slag increased cane and sugar yields as well as tissue Si concns. Application of 20 Mg slag ha-1 increased cumulative cane yields as much as 39% and sugar yields as much as 50% over the 3 crop years. Yield response to slag was generally greater from application immediately prior to sugarcane planting than to the preceding rice rotation crop. Without slag, ratoon yield production decreased as much as 45% in cane and 50% in sugar, whereas with slag, yields decreased only 28% in cane and 29% in sugar. The data indicate that the critical level for leaf Si may be greater than the previously reported value of 10 g kg-1, and that reduced yields in ratoon crops vs. plant crops were associated with lower Si levels. Consequently, more extensive Si deficiencies may exist in the Everglades than were previously considered. Other yield-limiting factors such as low soil Mg concns. were also shown to contribute to the decline of sugarcane ratoon yields. Diunduh dari: bin/sdcgi?APP=ftslink&action=reflink&origin=wiley&version=1.0&coi=1%3ACA S%3A528%3ADyaK3MXmslyrtLw%3D&md5=1a4ed1f59a9d5f6056cffd50d6ee0d8 2……… 4jan2013

55 Associations between host-plant nitrogen and infestations of the sugarcane borer, Eldana saccharina Walker (Lepidoptera: Pyralidae) P. R. Atkinson and K. J. Nuss Bulletin of Entomological ResearchBulletin of Entomological Research / Volume 79 / Issue 03 / September 1989, pp Infestations of Eldana saccharina Walker in South Africa are higher in intensively-grown than in peasant-grown sugarcane, and are worse in water- stressed plants. Although field trials showed negligible increases in the incidence of the pest with applied nitrogen, the degree in which the degree of water stress could not be controlled. Pot-plant trials, in which the degree of water stress was controlled as well as the amount of fertilizer, showed that the combination of nitrogen with stress resulted in increased survival of larvae and greatly increased biomass with shortened development times. Adults did not appear to choose stressed or fertilized plants in preference to normal or unfertilized ones. In every case, whether in the field or in insectary trials, increased infestation levels were associated with increased stalk total nitrogen. Amino acid determinations showed that the balance of individual acids did not appear to alter but that the balance of individual acids did not appear to alter but that glyphosate ripener had a similar effect to water stress, increasing all amino acids together. Infestations in older cane were disproportionately higher than in younger cane, weight for weight, despite reduced levels of stalk nitrogen. This anomaly may be due to the presence of phenolic compounds in younger cane, or in cane tops. Levels of nitrogen are much higher in the feeding sites of the insect in natural host-plants than in cane stalks, and the fecundity of feral moths natural hosts appeared to be higher than that of moths from sugarcane. The insect appears to have invaded sugarcane when stalk nitrogen levels reached sufficiently high levels for its survival as a result of intensive cultivation. Diunduh dari: d= ……… 4jan2013

56 . Influence of UV-B radiation and soluble silicates on the growth and nutrient concentration of sugarcane Elawad, S. H.; Allen, L. H., Jr.; Gascho, G. J. Proceedings - Soil and Crop Science Society of Florida (1985), 44, The effect of supplemental UV-B irradiance (22, 34, 45 mW/m2) and Na2SiO3 (0, 68, and 136 g/40-L pot) on leaf freckling, growth, and nutrient content of sugarcane (a trispecies hybrid of Saccharum, cv C.P ), grown in an organic soil was examined Plant height, stem diameter, leaf area, and dry-matter yields of both plant and ratoon crops were increased by silicate treatments. Silicate treatments also reduced attack by sugarcane stem borer (Diatraea saccharalis). Growth and yield were reduced by exposure to UV-B radiation. The highest UV-B treatment reduced dry-matter yields of plant and ratoon crops to 85 and 42% of the control, resp. In both plant and ratoon crops, application of Na2SiO3 increased the tissue concns. of Si, K, and Ca but decreased concns. of N, P, Mg, Fe, Mn, and Zn. Supplemental UV-B irradiance increased concns. of Si, Ca, Mg, Mn, and Cu in sugarcane leaves. Greenhouse-grown plants showed no symptoms of leaf freckling at any level of UV-B exposure by lamps. Plants grown outside the greenhouse without Si treatment showed severe leaf freckling although they were exposed only to natural UV-B irradiance. Plants grown outside also produced many tillers, especially when silicate was added. Plants grown inside the greenhouse did not tiller even with the highest rate of silicate. Therefore, sugarcane leaf freckling in the field can be controlled by Si, and it appears that UV-B radiation is not involved unless smaller wavelength ( nm) radiation at peak midday fluences are involved. Diunduh dari: bin/sdcgi?APP=ftslink&action=reflink&origin=wiley&version=1.0&coi=1%3ACA S%3A528%3ADyaL2MXmtV2qtr4%3D&md5=fbc10dfa7323c2ff899c18baa2c7f3f0 ……… 4jan2013

57 Soil and Plant Silicon and Silicate Response by Sugar Cane R. L. Fox, J. A. Silva, O. R. Younge, D. L. Plucknett and G. D. Sherman SSSAJ Vol. 31 No. 6, p Calcium silicate slag increased sugar yields 12 tons/hectare in a field where phosphate extractable soil silicon and trichloroacetic acid (TCA) extractable silicon of sugar cane (Saccharum officinarum) leaf sheaths were about 20 ppm. Large amounts of P or lime did not alleviate leaf freckle whereas slag did so to a marked degree. Acid solutions of phosphate, sulfate, acetate, and water can be used successfully as extractants for soil silicon. The general order for extractable silicon from soils developed on basalt and alluvium was: Humic Ferruginous Latosol < Humic Latosol < Low Humic Latosol < Dark Magnesium clay. This is also the order of decreasing weathering for these soils as indicated by total soil silicon and occurrence of secondary minerals. Leaf sheath silicon (TCA extractable) was especially well correlated with log extractable soil silicon (r = 0.97 for water extraction). Irrigation waters may contain much silicon and contribute greatly to the supply of extractable soil silicon and to plant silicon. Diunduh dari: https://www.soils.org/publications/sssaj/abstracts/31/6/SS …… … 4jan2013

58 Absorption and deposition of silica by four varieties of sorghum Lanning, F. C.; Linko, Yu-Yen Journal of Agricultural and Food Chemistry (1961), 9, Absorption and deposition of silica by 4 varieties of sorghum (Sorghum subglabrascens), Pink kafir, Spur feterita, Atlas and Dwarf yellow milo, were studied. Plants were grown in an open field and gathered at regular 3- week intervals throughout the growing season. Silica content of leaf sheaths and leaves of all varieties increased continuously throughout the season. Stems and seeds remained low and constant in silica content. The silica content of roots decreased during the first 3 to 6 weeks followed by a slight increase. There was a considerable variation in rate and amount of silica absorbed by the 4 varieties. Spur feterita absorbed the most and Dwarf yellow milo the least. Plants resistant to insects or diseases had a higher silica content at most stages than corresponding susceptible varieties. Diunduh dari: bin/sdcgi?APP=ftslink&action=reflink&origin=wiley&version=1.0&coi=1%3ACA S%3A528%3ADyaF38XksFOrsrY%3D&md5=e ee805be15787db1860c570b ……… 4jan2013

59 Potassium and Silicon Improve Yield and Juice Quality in Sugarcane (Saccharum officinarum L.) under Salt Stress M. Ashraf, Rahmatullah, R. Ahmad, M. Afzal, M. A. Tahir, S. Kanwal, M. A. Maqsood. Journal of Agronomy and Crop Science. Volume 195, Issue 4, pages 284–291, August 2009Volume 195, Issue 4, Soil salinity is a major abiotic stress which adversely affects the yield and juice quality in sugarcane. However, the mineral nutrient status of plant plays a crucial role in increasing plant tolerance to salinity. We investigated the effects of K and/or Si on plant growth, yield and juice quality in two sugarcane genotypes differing in salinity tolerance. Addition of K and Si significantly (P ≤ 0.05) increased K and Si concentrations and decreased the accumulation of Na + in plants under salt stress. Cane yield and yield attributes were significantly (P ≤ 0.05) higher where K and Si were added. Juice quality characteristics like Brix (% soluble solids in juice), Pol (% sucrose in juice), commercial cane sugar (CCS) and sugar recovery in both sugarcane genotypes were also significantly (P ≤ 0.05) improved with the supplementation of K and Si. For most of the growth parameters, it was found that K either alone or in combination with Si was more effective to alleviate salt stress in both sugarcane genotypes than Si alone. Moreover, the beneficial effects of K and Si were more pronounced in salt sensitive genotype than in salt tolerant genotype. The results suggested that K and Si counteracted the deleterious effects of high salinity/sodicity in sugarcane by lowering the accumulation of Na + and increase in K + concentration with a resultant improvement in K + /Na + ratio which is a good indicator to assess plant tolerance to salinity. Diunduh dari: 037X x/abstract?deniedAccessCustomisedMessage=&userIsAuthentica ted=false……… 4jan2013

60 Effect of silicon fertilization on yield and photosynthetic attributes in sugarcane (Saccharum officinarum L. hybrid). Huang HaiRongHuang HaiRong; Bokhtiar, S. M.; Xu Lin; Li YangRui; Yang LiTaoBokhtiar, S. M.Xu LinLi YangRuiYang LiTao Journal Guangxi Agricultural Sciences 2009 Vol. 40 No. 12 pp An experiment has been conducted in a green house to study the effect of calcium silicate fertilizer on yield contributing parameters, photosynthetic characteristics and N, P, K and Si content in sugarcane variety ROC 22. The treatments included a control with traditional fertilizer (26 g N+1.76 g P+20 g K per pot) only and six levels of silicon (20, 40, 60, 80, 120 and 150 g/pot) plus same amount of traditional fertilizer. The added Ca-silicate increased photosynthesis, transpiration and stomatal conductance significantly over non amended control. The influence of Si amendment on N concentration showed a significant decreasing tendency. Leaf tissue concentration for phosphorus did not differed remarkably, either a little effect or a slight increase in concentration at varying levels of Si application has been observed, but leaf tissue Si content increased progressively with increasing Si concentration in the soils. Si amended treatments significantly increased yield in dry matter (26%-70%) and in cane yield (30%-66%) per pot over non amended control. Analysis of TVD leaves showed up to 2.64% Si content at the harvest stage in Si treated plants. Diunduh dari: 0C E8EAEF1FC?gitCommit= ga6ad01a……… 4jan2013

61 Effect of calcium silicate on growth and dry matter yield of Chloris gayana and Sorghum sudanense under two soil water regimes E. Eneji, S. Inanaga, S. Muranaka, J. Li,P. An, T. Hattori, W. Tsuji Grass and Forage Science Volume 60, Issue 4, Volume 60, Issue 4, pages 393–398, December 2005 The effects of five rates [0 (control), 1, 2, 4 and 6 Mg ha −1 ] of calcium silicate on the growth and water consumption by rhodes grass (Chloris gayana Kunth) and sudan grass (Sorghum sudanense Piper) under wet and dry soil water regimes (60 g and 30 g H 2 O kg −1 soil respectively) were evaluated in a pot experiment. The effect of the application of silicate on plant biomass was similar to that of the control. However, the shoot and root dry mass varied significantly (P < 0.001) according to the soil water regime and plant species. During the first cut, the shoot dry mass was 5.7 g per pot under the wet soil moisture regime, significantly exceeding that under the dry soil water regime proportionately by For sudan grass, the shoot dry mass varied from 3.6 g per pot in the control to 4.3 g per pot in the treatment that received 6 Mg ha −1 of calcium silicate. Plant water demand decreased as the rate of calcium silicate application increased, suggesting that an application of calcium silicate could reduce drought stress and enhance water economy. For the soil under study, the reduction in plant water demand represents a water saving ranging from to nearly Diunduh dari: x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticat ed=false……… 4jan2013

62 Potential of Silicon Fertilization in Sugarcane Production in Louisiana. Brenda Tubana, Narayanaswamy Chowdappa, Josh Lofton, Yumiko Kanke, Marilyn Dalen and Lawrence Datnoff Tuesday, October 23, 2012 Many studies have documented the benefits of silicon (Si) fertilization particularly to Si accumulator plants such as sugarcane. Sugarcane is grown on the alluvial plain of Louisiana along the lower Mississippi River consisting of highly diverse soils. This study was conducted to document the potential benefits of Si fertilization to sugarcane grown on alluvial soils in south Louisiana. Three rates of calcium silicate slag (CaSiO 3 ; 2, 4, and 8 MT ha -1 ), including a control, were superimposed to three 1.8 m-row x 12 m-long plots prior to planting of three cane varieties (LCP , HoCP , and L ) in The treatments were arranged in a randomized complete block design with four replications established on Sharkey clay and Commerce silt loam soils in St. Gabriel, Louisiana. The effect of CaSiO 3 application was consistent across cane varieties. Sugarcane grown on Commerce silt loam had the highest sugar yield both in 2010 and 2011 with 2 MT CaSiO 3 ha -1 application rate. In 2010, an application of 4 MT ha -1 of CaSiO 3 raised % Si in stalk from 0.40 to 0.43% while Si removed by cane was increased by 48 kg ha -1 (P<0.05). Acetic acid-extractable (CH 3 COOH) Si was generally higher in Sharkey clay than in Commerce silt loam. There was a general pattern of increasing CH 3 COOH-extractable Si with increasing CaSiO 3 application rates but these increases declined with cropping year. All measured parameters in 2010 and 2011 were pooled; cane tonnage, sugar yield and Si removal rate were significantly increased (P<0.05) by CaSiO 3 fertilization for sugarcane grown on Commerce silt loam but not on Sharkey clay soil. Due to the nature of soils in the alluvial plain of Louisiana being highly diverse, some areas under sugarcane production may benefit from Si fertilization thus future research should focus on establishing the method for quantifying plant-available Si. Diunduh dari: … 4jan2013

63 EXTRACTABLE SILICON IN SOILS OF THE SUGAR INDUSTRY AND RELATIONSHIPS WITH CROP UPTAKE MILES, N; VAN ANTWERPEN R; VAN HEERDEN PDR; RHODES R, WEIGEL A, AND McFARLANE, S.A. Proc S Afr Sug Technol Ass (2011) 84: Evidence that elevated plant silicon (Si) levels reduce biotic stresses accounts largely for the current intense interest in the Si nutrition of sugarcane in South Africa. In terms of managing Si supplies to the crop uncertainties exist regarding, firstly, the reserves of plant-available Si in soils of the industry, and secondly, the reliability of soil test methods for predicting Si availability. Extractable Si was measured in 112 soils collected from sugarcane producing fields in South Africa. The regions sampled included the midlands, coastal areas and irrigated north. Extractants employed were 0.01 M CaCl2 and 0.02 N H2SO4. Extractable Si levels varied widely in the soils, with lowest values being found in the midlands and coastal areas. Soils from the irrigated north and the Umfolozi area were high in extractable Si. Sugarcane leaf Si concentrations from 28 sites were related to soil extractable Si levels. The CaCl2 soil test proved markedly superior to H2SO4 as a predicative test for leaf Si. Diunduh dari: content/uploads/Proceedings/2010s/2011-Miles-et-al.pdf……… 4jan2013

64 Yield responses of sugarcane to applied silicon (Si) are widely documented (Korndorfer and Lepsch, 2001). However, the current intense interest in the Si nutrition of sugarcane in South Africa is due largely to mounting evidence that elevated plant Si levels reduce biotic stresses (Savant et al., 1999). In the South African sugar industry, routine analysis of grower-submitted leaf samples reflects wide variations in leaf Si concentrations (van der Laan and Miles, 2010). Low leaf Si concentrations ( 1.0%). In areas where the crop is deficient in Si, there is a requirement for augmenting soil Si supplies through fertilisation. 1.Berthelson S, Hurney A, Noble AD, Rudd A, Garside AL and Henderson A (2001). An assessment of current silicon status of sugar cane production soils from Tully to Mossman. Proc Aust Soc Sugar Cane Technol 23: Korndorfer GH and Lepsch I (2001). Effect of silicon on plant growth and crop yield. In: LE Datnoff, GE Snyder and GH Korndorfer (Eds.) Silicon in Agriculture. Pp Savant NK, Datnoff LE and Snyder GH (1999). Silicon nutrition and sugarcane production: A review. J Plant Nutr 22: van der Laan M and Miles N (2010). Nutrition of the South African sugar crop: Current status and long-term trends. Proc S Afr Sug Technol Ass 83: Diunduh dari: ……… 4jan2013 EXTRACTABLE SILICON IN SOILS OF THE SUGAR INDUSTRY AND RELATIONSHIPS WITH CROP UPTAKE MILES, N; VAN ANTWERPEN R; VAN HEERDEN PDR; RHODES R, WEIGEL A, AND McFARLANE, S.A. Proc S Afr Sug Technol Ass (2011) 84:

65 Effects of silicon concentrations on management of powdery mildew and growth of Zucchini and Zinnia H.B. Tesfagiorgis(1) and M.D. Laing (1) (1). Discipline of Plant Pathology, School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa. Concentration of Silicon (Si) in the nutrient solution plays an important role in disease control, growth and yield of plants growing in hydroponic systems. Zucchini and zinnia were grown in re-circulating nutrient solutions containing Si at different concentrations. Effects of Si concentration in the solution on powdery mildew (PM) control and plant growth, and accumulation of Si and selected elements in different parts of these two plant species were determined. Increased concentrations of Si in the solution improved efficacy of Si against PM, accumulations of potassium (K) in the shoots, and Si in leaves and roots of both plants without affecting its distribution to other plant parts. Adding Si into the nutrient solution at mg ℓ-1 enhanced growth of plants by improving their uptake of P, Ca, and Mg. However, increased level of Si reduced accumulation of calcium (Ca) in plants and their growth and yield (for zucchini only). Leaves of both plant species, infected with PM fungi, accumulated higher levels of Si and Ca, but less P, than leaves of uninfected plants exposed to the same levels of soluble Si. For optimal disease control and maximum growth and yields of these two plants, hydroponic applications of Si at mg ℓ-1 are recommended. Diunduh dari: https://docs.google.com/viewer?a=v&q=cache:ki0Az8BeMHEJ:www.siliconconference.o rg.za/fotos/Abstract ……… 4jan2013 https://docs.google.com/viewer?a=v&q=cache:ki0Az8BeMHEJ:www.siliconconference.o rg.za/fotos/Abstract

66 Control of sugar beet root diseases (Rhizoctonia solani and Pythium spp.) using silicon and biological control (Bacillus and Pseudomonas spp.) S.T. Hadebe, K.S. Yobo and M.D. Laing Plant Pathology, School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, South Africa Corresponding Sugar beet is a temperate biennial root crop whose roots are rich in sucrose. Its yield potential is more than 200tons/ha in 7 months at 24% sucrose compared to 14% sucrose in 18 months for sugarcane. Root diseases are a major obstacle in cultivating sugar beet in South Africa. Silicon application has been shown to increase Silicon content in the roots and leaves of plants, and to enhance the plant immune systems. Biological control has been recognised worldwide as a safe and cheap method of controlling soilborne pathogens. Therefore the aim of this project is to investigate the potential of Silicon, Bacillus and Pseudumonas in controlling sugar beet root diseases caused by Rhizoctonia solani and Pythium. 121 Bacillus and 42 Pseudomonas isolates have been isolated so far. The bacterial isolates will be tested in the laboratory to see they roduce clearing zone or hinder growth of the pathogen hyphae. Replicates from successful bacteria will be screened to quantify clearing zones. Electron microscopy will be conducted visualise the interaction. Successful isolates will be tested in the greenhouse alone and in conjunction with Silicon against the pathogens. Silicon will also be tested alone against the pathogens. The parameters tested for in the greenhouse will be percentage germination and fresh and dry shoot weight of sugar beet seedlings. Diunduh dari: ……… 4jan2013

67 Effect of silicon on a sugarcane nematode community in KwaZulu-Natal S.D. Berry, P. Cadet and V.W. Spaull South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, Durban, Silicon (Si) is known to alleviate biotic and abiotic stresses in many crops. Most of the research on the biotic influence of Si has dealt with insects and fungi, there being no proper studies on the effect of Si on plant-parasitic nematodes. To investigate this effect, a replicated field trial was planted with sugarcane in KwaZulu-Natal, comparing two Si carriers, fly ash and filtercake (both by-products of the sugar milling process), with other treatments and an untreated control. Applying the Si carriers to the soil was not always sufficient to increase levels of Si in the sugarcane leaves. Uptake of Si by sugarcane required a particular chemical balance in the soil. As a consequence, Si treatment, per se, had no effect on the nematode community. However, a comparison between Si-rich and Si-poor plots, selected independently of the treatments, showed that total numbers of plant parasitic nematodes and numbers of Pratylenchus zeae and Helicotylenchus dihystera in the soil were significantly lower in plots where foliar Si levels were higher. The same trend was true for the number of P. zeae in the roots, but the difference was not significant. In a pot experiment, root Si was found to be correlated with foliar Si. Multivariate analysis showed that while numbers of some of the nematodes in the soil were depressed in the higher Si plots, this was not so for the most pathogenic species able to feed on the deeper cells within the roots. Potential consequences of this trend are discussed. Diunduh dari: ……… 4jan2013

68 Investigating and manipulating silicon uptake in sugarcane R.M. Jacob1, C. Phyfer1,2, B.A.M. Potier1, and D. Watt1,2 (1).South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe 4300, South Africa. (2) University of KwaZulu-Natal, School of Biological and Conservation Sciences, Private Bag X54001, Durban 4001, South Africa. The benefits of silicon (Si) amendments have been well documented in plants. These include enhanced productivity and tolerance to various biotic and abiotic stresses, such as freezing, drought, pests and diseases. In sugarcane (Saccharum spp. hybrids), Si application is especially beneficial in reducing infestations of the stalk borer Eldana saccharina. Studies have shown that South African sugarcane varieties vary in their ability to accumulate Si. The exact mechanisms of Si uptake and transport in sugarcane are unknown. However, there has been much progress made in understanding these mechanisms in rice, a typical Si- accumulating plant, efficient in the uptake and transport of silicon. Reported here are progresses made towards the development of a methodological approach to determine the mode of Si uptake, either active or passive, in sugarcane. Also reported are the initial molecular steps taken towards the manipulation of Si uptake by expressing an active Si transporter gene from rice. This work could allow the tailoring of South African varieties for increased Si uptake, which will be particularly useful for those varieties that are not able to accumulate Si at high enough levels to be beneficial. Diunduh dari: ……… 4jan2013

69 Induced resistance in sugarcane to stalk borer and thrips: is there a role for soluble silicon? M.G. Keeping1,2 and R.S. Rutherford1 1 ). South African Sugarcane Research Institute, Private Bag X02, Mt. Edgecombe ).School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville Induced plant resistance to insect herbivores may provide an opportunity to elevate the normally low endogenous pest resistance of susceptible crop cultivars to levels characteristic of resistant cultivars. Numerous studies have addressed the role of jasmonate (JA) and salicylate (SA) in inducing plant resistance to insects, while a small but growing research effort has explored the contribution of silicon (Si) in this regard. Silicon-amended sugarcane enjoys significantly greater resistance to stalk borer attack, but the relative contributions of amorphous versus soluble Si to plant defence have yet to be established. Adverse mechanical effects of silica on borer feeding efficiency and survival are likely. Trials incorporating Si, JA and SA treatments have indicated that while Si alone does not reduce infestations of sugarcane thrips, JA and SA may interact with Si to increase resistance to the insect, along with crop yield. This suggests that soluble, rather than amorphous Si may play a role in thrips resistance and that its effects are dependent on the concurrent activity of both JA and SA. As for Si-mediated defence against plant pathogens, there appears to be growing support for an active role of Si in anti-herbivore defence, in addition to its passive one. Diunduh dari: ……… 4jan2013

70 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Silicon (Si) is one of the most abundant elements found in the earth's crust, but is mostly inert and only slightly soluble. Agriculture activity tends to remove large quantities of Si from soil. Sugarcane is known to absorb more Si than any other mineral nutrient, accumulating approximately 380 kg ha-1 of Si, in a 12-month old crop. Sugarcane (plant growth and development) responses to silicon fertilization have been documented in some areas of the world, and applications on commercial fields are routine in certain areas. The reason for this plant response or yield increase is not fully understood, but several mechanisms have been proposed. Some studies indicate that sugarcane yield responses to silicon may be associated with induced resistance to biotic and abiotic stresses, such as disease and pest resistance, Al, Mn and Fe toxicity alleviation, increased P availability, reduced lodging, improved leaf and stalk erectness, freeze resistance, and improvement in plant water economy. This review covers the relationship of silicon to sugarcane crop production, including recommendations on how to best manage silicon in soils and plants, silicon interactions with others elements, and laboratory methodology for determining silicon in the soil, plant and fertilizer. In addition, a future research agenda for silicon in sugarcane is proposed. Diunduh dari: ……… 4jan2013

71 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Members of the grass family accumulate large amounts of Si in the form of silica gel (SiO2.nH2 O) that is localized in specific cell types. The function of Si in plants has been proposed as i) support for cell walls (resistance to lodging); ii) deterrence to pest and pathogens; iii) reduction in water loss by evapotranspiration; iv) reduction in certain heavy metal toxicities, and v) an essential element for normal development in some species. Diunduh dari: ……… 4jan2013

72 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Several reports in the literature suggest that Si nutrition has a definite agronomic role in sugarcane crop cultivation, especially on weathered tropical soils such as Oxisols, Ultisols, Entisols and Histosols (organic soils). Sugarcane absorbs large amounts of Si from soil. According to Samuels (1969), at 12-months the above ground parts contained 379 kg ha-1 of Si, compared with 362 kg ha-1 of K and 140 kg ha-1 of N. Ross et al. (1974) reported the removal of 408 kg ha-1 of total Si from soil by a sugarcane crop (tops + millable cane) yielding of 74 t ha -1. The removal of Si from soil could be more important in intensively cultivated areas. As a result of the Si export of this magnitude, a temporary depletion of bio-available Si in soils could also be a possible factor of declining yields of ratoon crops. In other words, there may be an apparent need for consideration of Si nutrient management in developing appropriate integrated nutrient management system for sustainable sugarcane production, especially in certain ecoregions having Si-deficient weathered soils and organic soils. 1.Ross, L., Nababsing, P., and Wong You Cheong, Y Residual effect of calcium silicate applied to sugarcane soils. In: International Cong. the Soc. Sugar Cane Technol. 15, Durban, Proc., 15(2): Samuels, G Silicon and sugar. Sugar y Azucar. 66(4): Diunduh dari: ……… 4jan2013

73 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): SILICON IN SOIL Silicon, after oxygen, is the most abundant element in the earth's crust, with soils containing approximately 32% Si by weight (Lindsay, 1979). Because of its abundance in the biosphere, the essentiality of Si as a micronutrient for higher plants is very difficult to prove. Even highly purified water contains about 20 nM Si (Werner and Roth, 1983) and; correspondingly, the leaves of Si accumulator plants that were subjected to a so-called no-silicon treatment usually contain between mg Si g-1 leaf dry weight. Literature on forms of Si and their reaction in soils has been reviewed by McKeague and Cline (1963ab); Jones and Handreck (1967); Mitchell (1975); Lindsay (1979); Hallmark et al. (1982); Drees et al. (1989); and Tan (1994). 1.Drees, L.R, Wilding, L.P, Smeck, N.E., and Senkayi, A.L Silica in soils:quartz and disordered silica polymorphs. In: J.B. Dixon, S.B. Weed, and R.C. Dinauer. (eds.) Minerals in soil environment (2nd Ed.) Soil Sci. Soc. Amer. Book Series. 1: Hallmark, C.T, Wilding, L.P., and Smeck, N.E Silicon. ASA. Agronomy Monograph 9: Lindsay, W.L Chemical Equilibrium in Soil. John Wiley & Sons, New York, NY. 4.McKeague, J.A. and Cline, M.G. 1963a. Silica in soil solutions. I. The form and concentration of dissolved silica in aqueous extracts of some soils. Can. J. Soil Sci. 43(1): McKeague, J.A. and Cline, M.G. 1963b. Silica in soil solution. II. The adsorption of monosilicic acid by soil and by other substances. Can. J. Soil Sci. 43: Mitchell, B.D Oxides. Hydroxides of silicon. pp In: J.E. Gieseking. (ed.) Soil Components, v. 2, Inorganic Components. Springer-Verlag, New York, NY. 7.Tan, K.H Environmental Soil Science. Marcel Dekker, Inc. New York. 8.Werner, D. and Roth, R Silica metabolism. pp In: Lauch A., Bielsky R.L. (Ed.) Inorganic Plant Nutrition, New Series. Spring-Verlog, New York, N.Y. Diunduh dari: ……… 4jan2013

74 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): The solid-phase of Si occurs in various discrete and associated forms in soils in well-ordered (quartz) and disordered polymorphs (e.g. opal), and clay- mineral lattice structures. The solubility of disordered or amorphous Si polymorphs in soils at an ambient temperature and neutral pH is approximately 50 to 60 mg Si L-1 ; whereas that of quartz is much lower, commonly 3 to 7 mg Si L-1 (Alexander et al., 1954; Krauskopf, 1959; Dapples, 1979; Hallmark et al., 1982). The liquid-phase of Si in soil is more complex, but agronomically important. It includes Si in soil solution mainly as monosilicic or orthosilicic acid [H4 SiO4 or Si(OH)4 ] and may range from 1 to 40 mg Si L-1 (McKeague and Cline, 1963a; Beckwith and Reeve, 1964; Jones and Handreck, 1963, 1967; Crook, 1968; Elgawhary and Lindsay, 1972), with 16 to 20 mg Si L-1 most common in soils near field capacity (Hallmark et al., 1982). 1.Alexander, G.B., Heston, W.M., and Iler, K.R The solubility of amorphous silica in water. J. Phys. Chem. 58: Beckwith, R.S. and Reeve, R Studies on soluble silica in soils. II - The release of monosilicic acid from soils. Aust. J. Soil Sci. 2: Dapples, E.C Silica as an agent in diagnosis. pp In: G.Larsen, G.V. Chilingar (eds) Diagnosis in Sediments and Sedimentary Rocks. Elsevier Sci. Publ. Co., New York, NY. 4.Elgawhary, S.M. and Lindsay, W.L Solubility of silica in soils. Soil Sci Soc. Am. Proc. Madison, 36: Hallmark, C.T, Wilding, L.P., and Smeck, N.E Silicon. ASA. Agronomy Monograph 9: Jones, L.H.P. and Handreck, K.A Silica in soils, plants, and animals. Adv. Agron. 19: McKeague, J.A. and Cline, M.G. 1963a. Silica in soil solutions. I. The form and concentration of dissolved silica in aqueous extracts of some soils. Can. J. Soil Sci. 43(1): Diunduh dari: ……… 4jan2013

75 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): According to Elgawhary and Lindsay (1972), a solid-phase that is less soluble than amorphous Si but more soluble than quartz controls Si in soil solution. Others have suggested that amorphous Si coatings formed due to dehydration (McKeague and Cline, 1963c), kaolinite and montmorillonite (Kittrick, 1969), a surface aluminosilicate component (R) of variable composition (Weaver and Bloom, 1977), and/or opal (Wilding et al., 1979) might regulate the amount of Si in the soil solution. As monosilicic acid loses water, it forms socalled silica gel until the proper moisture content is reached. When the dissolved Si in soil solution exceeds 65 mg Si L-1, polymerization of Si usually occurs and a mixture of monomers and polymers of Si(OH)4 and Si-organic compounds may be found in soil solution at a given time (Tan, 1994; Matichenkov and Ammosova, 1996). The solubility of Si (both crystalline and amorphous) is essentially constant between the pH limits of 2 and 8.5, but increases rapidly above 9. The rapid rise in solubility above 9 is due to ionization of monosilicic acid, as illustrated below: Si(OH)4 +OH Si(OH)3 O- + H2 O H4SiO4 + OH H3 SiO4 - + H2 O 1.Elgawhary, S.M. and Lindsay, W.L Solubility of silica in soils. Soil Sci Soc. Am. Proc.Madison, 36: Kittrick, J.A Soil minerals in the Al2O3-SiO2-H2O system and a theory of their formation. Clays Clay Miner. 17: Matichenkov, V.V. and Ammosova, Y.M Effect of amorphous silica on soil properties of a sod-podzolic soil. Eurasian Soil Sci. 28(10): McKeague, J.A. and Cline, M.G. 1963c. Silica in the soil. Adv. Agron. 15: Weaver, R.M., and Bloom, P.R Solution activities of aluminum and silicon in highly weathered soils that contain gibbsite and kaolinite. Soil Sci. Soc. Am. J. 41: Wilding, L.P., Hallmark, C.T., and Smeck, N.E Dissolution and stability of biogenic opal. Soil Sci. Soc. Am. J. 43: Diunduh dari: ……… 4jan2013

76 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): The relationship observed by Ayres (1966) between Si in the sugarcane leaf and soil Si extracted by 0.5 N ammonium acetate (pH 4.0), implies that the plant uptake of Si is governed by the concentration of Si in the soil solution. If the concentration of monosilicic acid, although varying in soils of same pH, is being maintained at a steady level by soil reserves, the highly weathered soils are bound to become severely depleted in Si if continuously cropped with sugarcane. The concentration of Si in soil solution seems to be controlled more by chemical kinetics than by thermodynamics (Hallmark et al., 1982), and apparently has no relationship to the total in the soil. However, where Si in solution is higher (soluble Si), the plant content of this element generally is greater (Korndörfer et al., 1999a). According to Drees et al. (1989) the dissolution kinetics of soil Si are influenced not only by nature of Si polymorphs but also by a myriad of soil factors such as organic matter, redox potential, metallic ions, phyllo-silicates, sesqui-oxides, surface area, surface coatings, and overall soil solution dynamics. Organic compounds such as alginic acid, ATP, and amino acids may enhance the dissolution of soil Si (Evans, 1965). Crook (1968) as is demonstrated by the high rates of dissolution of soil Si, including quartz, to leachates containing organic matter, with the Si going into solution as complexes Si-organic molecules. However, Douglas et al., (1984) did not find a correlation between the large concentrations of soluble organic carbon and monosilicic acid movement in the leachate. Sadzawka and Aomine (1977) reported that humus protected soil Si from dissolution and at the same time prevented Si from adsorption by soils. These observations suggest that the role of soil organic matter in Si dissolution is rather complex and needs further clarification. 1.Crook, K.A.W Weathering and roundness of quartz sand grains. Sedimentology 11: Douglas Jr, C.L, Allmaras, R.R., and Roager Jr, N.C Silicic acid and oxidizable carbon movement in a Walla silt loam as related to long-term management. Soil Sci. Soc. Am. J., 48: Evans, W.P Facets of organic geochemistry. pp In: E.C. Hallsworth, D.V. Crawford (eds.) Experimental Pedology. Butterworth Co. Ltd., London, England. 4.Sadzawka, R.M.A. and Aomine S Adsorption of silica in river waters by soils in Central Chile. Soil Sci Plant Nutr. 23: Diunduh dari: ……… 4jan2013

77 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Diunduh dari: ……… 4jan2013

78 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Effect of different Si sources on sugarcane dry matter Diunduh dari: ……… 4jan2013

79 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Sugarcane is a Si accumulator plant, which strongly responds to Si supply. The Si form that which sugarcane usually absorbs has no electric charge (H4SiO4) and is not very mobile in the plant. Because the uptake of undissociated H4 SiO4 may be nonselective and energetically passive, and its transport from root to shoot is in the transpiration stream in the xylem, the assumption has sometimes been made that the movement of Si follows that of water (Jones and Handreck, 1965). The silicic acid is deposited mainly in the walls of epidermal cells, where it is integrated firmly into the structural matter and contributes substantially to the strength of the stem. 1.Jones, L.H.P. and Handreck, K.A Studies of silica in the oat plant. III. Uptake of silica from soils by plant. Plant Soil 23: Diunduh dari: ……… 4jan2013

80 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): The distribution of Si within the shoot and shoot parts is determined by the transpiration rate of the part (Jones and Handreck, 1967). Most of the Si remains in the apoplasm mainly in the outer walls of the epidermal cells on both surfaces of the leaves as well as in the inflorescence bracts of graminaceous species and is deposited after water evaporation at the end of the transpiration stream, (Hodson and Sangster, 1989). Silicon is deposited either as amorphous b (SiO2. hH2O, 'opal') or as socalled opal phytoliths with distinct threedimensional shapes (Parry and Smithson, 1964). The preferential deposition of Si in the apoplasm of epidermal cells and trichomes is reflected in similarities between surface features of leaf and structure of Si deposits (Lanning and Eleuterius, 1989). The epidermal cell walls are impregnated with a firm layer of Si and become effective barriers against both fungal infections and water loss by cuticular transpiration. Despite that, there is increasing evidence for the necessity to modify the traditional view of Si deposition in the cell walls as a purely physical process leading to mechanical stabilization (rigidity) of the tissue and acting as a mechanical barrier to pathogens. 1.Hodson, M.J. and Sangster, A.G Silica deposition in the inflorescence bracts of wheat (Triticum aestivum). II. X-Roy microanalysis and backascattered electron imaging. Can J. Bot. 67(2): Jones, L.H.P. and Handreck, K.A Silica in soils, plants, and animals. Adv. Agron. 19: Lanning, F.C. and Eleuterius, L.N Silica deposition in some C3 and C4 species of grasses, sedges and composites in the U.S.A. Ann. Bot. 63: Parry, D.W. and Smithson, F Types of opaline silica deposition in the leaves of British grasses. Ann. Bot. London, 28: Diunduh dari: ……… 4jan2013

81 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Silicon may be involved in cell elongation and/or cell division. In a field study, plant crop height was quadratically related to the rate of Si applied, while plant crop stem diameter was linearly related (Elawad et al., 1982a). Gascho (1978) reported that application of TVA slag and Na silicate to greenhouse grown sugarcane increased plant height. Phicket (1971) indicated that some of the effects of Si on sugarcane were longer stalks with larger diameters and increased number of suckers. These observations on cane and observations for other crops suggest a possible role of Si in cell elongation and/or cell division (Elawad et al., 1982ab). Ayres (1966) determined that only 15% of the total plant Si are present in sugarcane stalks at 14 months. The leaf sheaths on the best cane-growing soils contained about 2.5 percent Si. Using the sixth leaf sheath, Halais (1967) suggested critical levels of 1.25 percent of Si and 125 mg dm-3 of Mn. If the Si level was below this value, Si responses could be expected. Under field conditions, in Florida, Anderson (1991) suggested that at least 1% Si (~2.1 % SiO2 in the leaf dry matter) is required for optimal cane yield. At 0.25% Si the yield drops to about 50%. According to Rodrigues (1997), increasing Si rate from 0 to 924 kg ha-1 using Wollastonite, resulted in substantial increase of the Si content in the leaves from 0.7 to 1.93 % and Si in the soil from 14 to 46 mg dm-3. 1.Anderson, D.L Soil and leaf nutrient interactions following application of calcium silicate slag to sugarcane. Fert. Res. 30(1): Elawad, S. H, Street, J. J., and Gascho, G. J. 1982b. Response of sugarcane to silicate source and rate. II - Leaf freckling and nutrient content. Agron. J. Madison. 74: Halais, P Si, Ca, Mn contents of cane leaf sheaths, a reflexion of pedogensis. Rep. Maurit. Sug. Ind. Res. Inst pp Rodrigues, G.P Efeito do silicato de cálcio na cana-de-açúcar e sobre as características químicas do solo. Monografia. Curso de Agronomia. Univ. Fed. Uberlândia, Brazil. Diunduh dari: ……… 4jan2013

82 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Better Si-accumulating cultivars may have the advantage of requiring lower rates of Si fertilizer or less frequent applications. A relatively narrow base of sugarcane germplasm demonstrated significant variability for Si content in leaf tissue (Deren et al., 1993). Korndörfer et al. (1998a) also found that sugarcane cultivars have different capacities to accumulate Si in the leaves. The Si levels in the leaf were of 0.76, 1.04 and 1.14% respectively for the cultivars: RB72454, SP and SP Deren, C.W, Glaz, B., and Snyder, G. H Leaf-tissue silicon content of sugarcane genotypes grown on Everglades Histosols. J. Plant Nutr. 16(11): Korndörfer, G.H., Colombo, C.A. & Rodrigues, L.L Effect of thermo- phosphate as silicon source for sugarcane. Inter-American Sugar Cane Seminar Sept., Miami, FL. Diunduh dari: ……… 4jan2013

83 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Increased SUGARCANE Yields Research work demonstrating the use of silicate slag as a source of Si for sugarcane has been largely conducted in Hawaii, Mauritius, and Florida. Yield responses are great enough that sugarcane grown in the Everglades (South Florida) is routinely fertilized with calcium silicate when soil tests indicate the need. However, Si fertilization requires large quantities of slag (generally 5 Mg ha-1), making it quite costly (Alvarez et al., 1988). Yields of cane and sugar in Hawaii have been increased % on soils low in Si, and many sugar plantations regularly apply calcium silicate in responsive fields (Ayres, 1966; Clements, 1965a; Fox et al., 1967b). Increased yields of sugarcane in fields have been reported in Mauritius (Ross, 1974) and Puerto Rico (Samuels, 1969); while in South Africa (Preez, 1970) and Brazil (Gascho and Korndörfer, 1998), several sources of silicate increased sugarcane yields in pots. In 1961, D'Hotman reported large increases in sugarcane yields from massive applications of finely ground basalt to soils in Mauritius. In similar work, Halais and Parish (1964) found increased Si in leaf sheaths and increased yields of sugarcane with the application of basalt dust. Ayres (1966) found that the Si of calcium silicate slag acts as a growth stimulant for sugarcane on low Si soils in Hawaii. 1.Alvarez, J., Snyder, G.H., Anderson, D.L., and Jones, D.B Economics of calcium silicate slag application in a rice-sugarcane rotation in the Everglades. Agric-System. Elsevier Publishers. 28 (3): Clements, H. F. 1965a. The roles of calcium silicate slag in sugar cane growth. Repts. Hawaiian. Sugar Tech. 25: Fox, R.L, Silva, J.A, Younge, O.R, Plucknett, D.L., and Sherman, G.D. 1967b. Soil and plant silicon and silicate response by sugar cane. Soil Sci. Soc. Am. Proc. Madison. 31(6): Gascho, G.J. and Korndörfer, G.H Availability of silicon from several sources determined by chemical and biological methods. Abstract. Annual Meeting Soil Sci. Soc. Am. Baltimore, MD Oct, p Halais, P. and Parish, D.H Silica and manganese contents of cane leaf sheaths in relation to soil and nutrition. Rep. Maurit. Sug. Ind. Res. Inst : Diunduh dari: ……… 4jan2013

84 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): The benefits of Si fertilization are generally observed in sugarcane grown on Si-deficient soils such as weathered tropical soils and Histosols. Ayres (1966) obtained increases in tonnage of sugarcane amounting to 18% in cane and 22% in sugar for plant cane crop following the application of 6.2 t ha-1 of electric furnace slag to aluminous humic ferruginous latosols in Hawaii. The beneficial effect of the slag lasted on low Si soils for four years, and the first ratoon crop produced about 20 % more cane and sugar. In Mauritius, calcium silicate slag applied at 7.1 t ha-1 to low Si soils (less than 77 mg dm- 3 Si extractable with modified Truog's extractant) at planting gave annual cane increases that were economically profitable over a 6-year cycle. A net return from the application of calcium silicate could be expected if the total Si level in the third leaf lamina was below 0.67 % of Si or if the acid- soluble soil Si was below 77 mg dm-3 Si (Ross et al., 1974) 1.Ayres, A.S Calcium silicate slag as a growth stimulant for sugarcane on low-silicon soils. Soil Sci. 101(3): Ross, L., Nababsing, P., and Wong You Cheong, Y Residual effect of calcium silicate applied to sugarcane soils. In: International Cong. the Soc. Sugar Cane Technol. 15, Durban, Proc., 15(2): Diunduh dari: ……… 4jan2013

85 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Since Si plays the role of a beneficial nutrient in sugarcane, it improves cane plant growth. Application of TVA and Florida calcium silicate slag (up to 20 t ha-1) to sugarcane (cv. CP ) grown in a Pahokee muck soil increased plant height, stem diameter, number of millable stalks, and cane and sugar yields in both plant and ratoon crops (Elawad et al., 1982a). This suggested that Si improved the photosynthetic efficiency of individual plants as well as of the whole stand. They observed application of 15 t ha-1 of slag increasing cane and sugar yields by 68% and 79% in plant crop, and by 125% and 129% in the ratoon crop, respectively. Similar results have been reported in Taiwan (Shiue, 1973), Australia (Hurney, 1973) and Puerto Rico (Samuels, 1969). In most of the above reports, the increases in cane and sugar yields associated with the application of silicate materials have been attributed to the increased number of millable stalks and increased plant size, and not to Pol reading. 1.Elawad, S.H., Street, J.J., and Gascho, G.J. 1982a. Response of sugarcane to silicate source: and rate. I. Growth and yield. Agron. J. Madison, 74(3): Hurney, A.P A progress report on calcium silicate investigation. In: Proc. of Conf. of Queensland Soc. of Sugar Cane Technol. Brisbane, Australia. 40: Samuels, G Silicon and sugar. Sugar y Azucar. 66(4): Shiue, J.J Criteria for predicting silicate slag demand for sugar cane. Rep.Taiwan Sug. Res. Inst. 59: Diunduh dari: ……… 4jan2013

86 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Water stress under field conditions is common and affects cane yields. Improved Si nutrition may reduce excessive leaf transpiration (Wong You Cheong et al., 1972). One of the symptoms associated with Si deficiency is the excessive rate of transpiration. The rate of transpiration of Si deficient plants increased by about 30% over the rate of control plants (Lewin and Reimann, 1969) (rates were measured as grams of water lost through transpiration per gram of dry weight per day). Okuda and Takahashi (1965) obtained a similar result, but found that in barley the effect was small (less than a 10% difference between Si deficient and control plants). This observation suggests a role for Si in the water economy of the plant. An increased rate of transpiration in Si-deficient plants could explain the wilting that may occur, particularly under conditions of low humidity, and could also help to explain the increased accumulation of Mn and other mineral nutrients in the aerial parts of Si deficient plants. The rate of transpiration is presumably influenced by the amount of silica gel associated with the cellulose in the cell walls of epidermal cells. Hence, a well thickened layer of silica gel should help to retard water loss, while epidermal cell wall with less silica gel will allow water to escape at an accelerated rate. 1.Lewin, J. and Reimann, B.E.F Silicon and plant growth. Annual Rev. Plant Physiol. 20: Okuda, A. and Takahashi E The role of silicon. pp In: The Mineral Nutrition of the Rice Plant. John Hopkins Press, Baltimore, MD. 3.Wong You Cheong, Y., Heits, A., and De Ville, J Foliar symptoms of silicon deficiency in the sugarcane plant. In: Cong. Intern. Soc. Sugarcane Techno. 14, New Orleans, 1971, Proceedings. Baton Rouge, LA 14: Diunduh dari: ……… 4jan2013

87 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): One other effect of increased plant Si content, which has been reported in literature, is the increased mechanical strength of plant tissue, which results in reduced lodging. Under field conditions, particularly in dense stands of sugarcane, Si can stimulate growth and yield by decreasing mutual shading by improving leaf erectness, which decreases susceptibility to lodging. Leaf erectness is an important factor affecting light interception in dense plant population and, hence, photosynthesis. In rice, Si supply increased the photo assimilation of carbon, especially after heading, and promoted the translocation of assimilated carbon to the leaves. This effect of Si on leaf erectness is mainly a function of the Si depositions in the epidermal layers of the leaf panicle (Takahashi and Miyake, 1982). 1.Takahashi, E, Ma, J.F., and Miyake, Y The effect of silicon on the growth of cucumber plant. Proc. 9th Inter Plant Nutrition Colloquium. Warwick University, U.K. pp Diunduh dari: ……… 4jan2013

88 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Few investigations of the role of Si in sugarcane have considered the mechanism by which it affects sugarcane tonnage production. However, Alexander et al. (1971) has undertaken the task of finding the role that Si plays in the synthesis, storage and retention of sucrose in the sugarcane plant. He found that sucrose inversion in sugarcane juice samples was delayed for several days by adding sodium metasilicate immediately after milling. Chromatographic evidence suggests that at low levels metasilicate forms a physical complex with sucrose which prevents the union of invertase with its substrate. The hypothetical fructose-silicate configuration is retained even after sucrose is inverted, thereby preventing fructose from being metabolized by microorganisms. Fructose appears to be the preferential hexose for microbial growth, i.e. most suitable carbon source. The effective preservation of fructose by silicates may constitute a bacterial repression operating in addition to the invertase-inhibitory action. Next to K, Si is the most extensive constituent of ash in sugarcane juice. It is the highest component of millable stalks ash and represents an even greater percentage in leaves. However, silicates in cane are believed to be one of the major contributors to mill roll wear. 1.Alexander, A.G, Acin-Diaz, N., and Montalvo-Zapata, R Inversion control in sugarcane juice with sodium metasilicate. Proc. Int. Soc. Sugar Cane Technol. 14: Diunduh dari: ……… 4jan2013

89 Savant, N. K, Korndorfer, G. H., Datnoff, L. E. and Snyder, G. H Silicon nutrition and sugarcane production: a review. J. Plant Nutr. 22 (12): Silicon application rates are mainly influenced by the chemical makeup of the Si source, Si levels in the soil, and in the plant. In Hawaii, the first silicate recommendation for plant cane was made in 1962 for 7.5 tons ha-1 of TVA (Tennessee Valley Authority) slag. In 1970, 4.94 t ha-1 of Hawaiian Cement corporation calcium metasilicate (CaSiO3) was recommended. The reduction in the rate was due to the greater reactivity of CaSiO3 as compared with TVA slag. Subsequently, in 1971 a tentative recommendation of 1.2 to 2.5 t ha-1 of CaSiO3 was made for ratoon cane, if the soil Si level was between 64 to 78 kg ha-1. Based on the economic evaluation of field trials conducted on McBryde and Lihue plantations during 1976 to 1982, the following CaSiO3 recommendations for sugarcane in Hawaii have been revised based on soil and plant Si indexes: 1.For fields not fertilized with CaSiO3 for two or more consecutive crops, apply 4.48 t ha-1 CaSiO3 to the current crop if soil Si levels are at or below the critical level of 112 kg ha-1. 2.For fields to which CaSiO3 was applied to one or both of the preceding crops (plant cane and ratoon), apply 2.24 t ha-1 CaSiO3 to the current crop if the soil Si levels are at or below the critical level of 78 kg ha-1. Thereafter, apply 2.5 t ha-1 to each succeeding crop if soil Si levels fall below 78 kg ha-1. 3.The critical levels for the "Crop log“ sheath Si (0.7 %) and the Mn/SiO2 ratio = 75 established by Clements (1965a) remain the same; if sheath Si levels of "Crop Log" samples are less than 0.7% or the sheath Mn/SiO2 ratios are above 75, apply 2.5 t ha-1 of CaSiO3 to the current crop (Hagihara and Bosshart, 1984). 1.Hagihara, H.H. and Bosshart, R.P Revised calcium silicate recommendation for plant and ratoon crops. Reports. Annual conference. Hawaiian Sugar Technol. (43rd). Presented at the annual conference “Productivity Through People and Technology”, November 13-14, Honolulu, HI Diunduh dari: ……… 4jan2013

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