PENTINGNYA KALIUM BAGI PERTANAMAN TEBU Foto: smno.tebu.plemahan.jan2013 1

Kalium terlibat dalam banyak aspek fisiologis tanaman: FUNGSI K BAGI TANAMAN Kalium terlibat dalam banyak aspek fisiologis tanaman: Mengaktivkan berbagai jenis ensim Membantu fotosintesis Mendorong status energi yang tinggi Mempertahankan turgor sel Meregulasi membukanya stomata daun Membantu penyerapan air Meregulasi pengangkutan hara dalam tanaman Membantu pengangkutan dan penyimpanan karbohidrat Membantu penyerapan N dan sintesis protein Membantu sintesis pati dalam daun 2

KALIUM BAGI TANAMAN TEBU   Kalium diserap dalam bentuk K+, kalium banyak terkandung pada abu. Pucuk tebu yang muda mengadung 60-70% K2O. Di dalam 1 ton hasil panen tebu terdapat sekitar 1,95 kg N; 0,30 - 0,82 kg P2O5 dan 1,17 - 6,0 kg K2O yang berasal dari dalam tanah. Kalium terdapat didalam sel-sel yaitu sebagai ion-ion didalam cairan sel dan sebagai persenyawaan adsorptif didalam zat putih telur dari sitoplasma. Inti sel tidak mengandung kalium. Sebagai ion didalam cairan sel, Kalium berperan dalam melaksanakan “turgor” yang disebabkan oleh tekanan osmotis. Diunduh dari: ………. 3

FUNGSI K DALAM TANAMAN . Dalam metabolisme tanaman tebu, kalium juga berfungsi sebagai activator ensim; K sangat penting dalam sintesis dan translokasi sukrosa dari daun menuju ke jaringan simpanan dalam batang. Kalium juga berperan dalam mengendalikan hidrasi dan osmosis dalam guard-cell stomata. Pergerakan karbohidrat dari daun menuju batang berlangsung dengan kecepatan sekitar 2.5 cm / minute dalam tanaman yang kecukupan kalium; kekurangan kalium akan meredukasi kecepatan pengangkutan ini hingga separuhnya. Oleh karena itu kekurangan K dalam tanaman akan mengakibatkan sebagian hasil fotosintesis tetap berada di daun, tidak dapat dikirim dan disimpan dalam batang. Selanjutnya kalau tanaman kekurangan kalium, aktivitas hidrolisis dari ensim invertase akan meningkat dan hasilnya adalah tanaman tebu kaya gula-reduksi dan kandungan sukrosenya rendah. Diunduh dari: ………. 4

. KEKURANGAN K   Tanaman yang kekurangan Kalium akan cepat mengayu atau menggabus, hal ini disebabkan kadar lengasnya yang lebih rendah. Kalium berpengaruh baik pada pembentukan dinding-dinding sel lebih baik keadaannya dan lebih baik kandungan airnya, sel-sel ini tumbuh lebih baik, lebih kuat dan lebih panjang. Kalium dalam tanaman tebu bersifat mobile, gejala awal defisiensi K muncul pada daun-daun tua. Bagian tepi dan pucuk daun-daun tua menunjukkan gejala klorosis kuning-orange dengan becak-becak khlorosis dan selanjutnya menjadi becak-becak klorosis kecoklatan. Gejala ini akan mengurangi luas daun hijau dan dapat mereduksi kemampuan fotosintesis tanaman. Kalau laju fotosintesis menurun dengan meningkatnya tingkat keparahan defisiensi K, pertumbuhan tanaman akan terhambat, ruas menjadi memendek dan batang tebu menjadi lebih pendek, demikian juga diameter batang tebu menjadi lebih kecil. Tanaman tebu yang defisien K tidak mampu berfotosintesis dengan baik kalau kadar K-daun mencapai 0.40 % K atau kurang. Diunduh dari: ………. 5

PEMUPUKAN K TEBU   Respon tebu terhadap pemupukan kalium sangat tergantung pada ketersediaan kalium dalam tanah. Tanaman tebu mempunyai kemampuan yang kuat untuk menyerap kalium dari dalam tanah. Waktu aplikasi pupuk K juga berpengaruh terhadap hasil dan status hara tanaman tebu. Penangguhan seluruh atau separuh dosis pupuk rekomendasi 150 Kg K/ha hingga periode puncak pertumbuhan tanaman tebu tidak berpengaruh terhadap hasil dan status hara K tanaman tebu. Di daerah-daerah dengan curah hujan kurang dari 2000 mm per tahun (di Mauritius), kebutuhan K tebu hingga ratoon ke enam dapat dipenuhi dengan sekali aplikasi upupk K pada saat tanam bibit. Aklan tetapi di daerah dengan curah hujan lkebih dari 2000 mm per tahun, aplikasi pupuk K setiap tahun memberikan hasil lebih baik. Diunduh dari: ………. 6

MEMPERBAIKI KETERSEDIAAN HARA TANAH ASAM HUMAT + PUPUK NPK MEMPERBAIKI KETERSEDIAAN HARA TANAH Aplikasi asam humat bersama dengan pupuk NPK meningkatkan ketersediaan unsur hara dalam tanah (Vertisol dan Alfisol) bagi tanaman. Perlakuan aplikasi terbaiki adalah 10 kg ha-1 asam humat (soil application) + 0.1% asam humat semprotan daun (dua kali) + 0.3% asam humat + 100% NPK dosis rekomendasi. Perlakuan lain yang sama baiknya adalah aplikasi asam humat 20 kg ha-1 HA (soil application) + 100% NPK dosis rekomendasi. Sumber: Journal Acta Agronomica Hungarica Volume 52, Number 3 / November 2004 7

Tanaman tebu yang sehat biasanya mengandung kalium lebih dari KALIUM & KUALITAS TEBU KALIUM merupakan kation yang banyak terakumulasi dalam cairan sel tanaman tebu. Tanaman tebu yang sehat biasanya mengandung kalium lebih dari 200 kg K/ha. Kalau suplai kalium tidak mencukupi, indikator yang paling terpengaruh adalah panjang-batang yang dapat digiling, dan jumlah batang anakan. Kalium juga berfungsi sebagai aktivator ensim, K sangat penting dalam proses sintesis dan translokasi sukrose dari daun ke jaringan simpanan sukrose di batang tebu. Respon tanaman tebu terhadap pupuk K sangat tergantung pada ketersediaan K-tanah, respon yang signifikan hanya terjadi pada tanah-tanah yang kandungan K-tersedianya rendah Biasanya tanaman tebu respon terhadap pupuk K dengan peningkatan hasil tebu, tanpa peningkatan kadar sukrose. Serapan K yang berlebihan oleh tanaman tebu dapat “menekan atau membatasi” recovery sukrose selama penggilingan. Sehingga pemupukan K harus dibatasi untuk mencukupi produksi optimum dan untuk membantu regulasi kemasakan, sehingga hasil gula maksimum dapat diperoleh dari batang tebu yang dapat digiling. 8

Tanaman tebu yang sehat biasanya mengandung kalium lebih dari KALIUM & KUALITAS TEBU KALIUM merupakan kation yang banyak terakumulasi dalam cairan sel tanaman tebu. Tanaman tebu yang sehat biasanya mengandung kalium lebih dari 200 kg K/ha. Kalau suplai kalium tidak mencukupi, indikator yang paling terpengaruh adalah panjang-batang yang dapat digiling, dan jumlah batang anakan. Kalium juga berfungsi sebagai aktivator ensim, K sangat penting dalam proses sintesis dan translokasi sukrose dari daun ke jaringan simpanan sukrose di batang tebu. Respon tanaman tebu terhadap pupuk K sangat tergantung pada ketersediaan K-tanah, respon yang signifikan hanya terjadi pada tanah-tanah yang kandungan K-tersedianya rendah Biasanya tanaman tebu respon terhadap pupuk K dengan peningkatan hasil tebu, tanpa peningkatan kadar sukrose. Serapan K yang berlebihan oleh tanaman tebu dapat “menekan atau membatasi” recovery sukrose selama penggilingan. Sehingga pemupukan K harus dibatasi untuk mencukupi produksi optimum dan untuk membantu regulasi kemasakan, sehingga hasil gula maksimum dapat diperoleh dari batang tebu yang dapat digiling. 9

K dan KUALITAS TEBU Kadar sukrose nira tebu sangat ditentukan oleh varietas dan kondisi iklim, pemupukan hanya salah satu faktor yang ikut mempengaruhi rndemen. Biasanya hasil penelitian pemupukan kalium menunjukkan bahwa respon hasil tebu terhadap pupuk K tidak diikuti dengan peningkatan sukrose dalam tebu. Hasil penelitian di Afrika selatan, peningkatan dosis pupuk K yang tidak mendatangkan respon hasil tebu, ternyata hanya sedikit berpengaruh pada kualitas tebu. Aplikasi pupuk kalium secara bertahap dua kali (50% saat tanam dan 50% pada akhir musim) memberikan hasil tebu dan jumlah batang tebu yang maksimum, sedangkan kualitas nira tidak terpengaruhi. 10

KALIUM DAN RENDEMEN TEBU K has a tendency to increase sucrose solubility during sugar processing, thus maintaining a certain amount of sucrose in solution, one K+ tying up one molecule of sucrose. A significant depression in sucrose concentration of cane following an application of 183 kg K ha–1 in South Africa. Chapman (1980) observed in long term trials in Australia that 196 kg K ha–1 slightly decreased sucrose content in cane when compared to the no K treatment. A more vivid example of K lowering sucrose recovery is provided by Korndorfer (1990) who observed that vinasse (distillery slops) when applied at 120 m3 ha–1 to a dark red dystrophic latosol in Brazil increased cane yield from 98 to 127 t ha–1 but decreased recoverable sucrose concentration in cane from 15.0 to 13.1%. 11

REKOMENDASI PUPUK K TANAMAN TEBU Persen Liat Tanaman kg K2O/ha Less than 30% Plant crop 90 to 210 Subsequent ratoons 150 to 210 More than 30%, exc. high base saturation soils 120 to 240 180 to 240 More than 40% clay and high base saturation 120 to 300 240 to 300 Sumber: SASRI-FAS, 2002. 12

Sumber: Better Crops International, Vol. 14, No. 1, May 2000 PUPUK K TANAMAN TEBU Aplikasi pupuk K dapat meningkatkan hasil tebu dan rendemennya kalau tanahnya mengandung kalium kurang dari 102 ppm. Dosis optimum pupuk K sekitar 140 kg/ha dapat meningkatkan hasil gula sekitar 2.8 t/ha. Aplikasi pupuk N dan K mampu meningkatkan hasil gula pada lahan tebu yang miskin kalium. Kalium memperbaiki metabolisme N tanaman dan kalium menjadi faktor pembatas untuk produksi gula di lahan ini. Tingkat kritis untuk respon K pada tanah-tanah ini adalah sekitar 102 ppm K-terekstraks. Tanah-tanah dnegan kandungan K-ekstraks lebih dari 140 ppm tidak respon terhadap pupuk kalium. Sumber: Better Crops International, Vol. 14, No. 1, May 2000 13

Sumber: Nutrient Cycling in Agroecosystems WAKTU APLIKASI PUPUK K Waktu aplikasi pupuk K berpengaruh terhadap hasil tebu dan status nutrisi K tanaman tebu. Penangguhan seluruh atau separuh dosis pupuk rekomendasi 150 Kg K/ha hingga bersamaan dengan saat puncak pertumbuhan tanaman tebu ternyata tidak berpengaruh pada hasil tebu dan status hara tanaman. Di daerah dengan curah hujan lebih dari 2000 mm per tahun, sebaliknya pemupukan kalium dilakukan setiap tahun pada saat tanam (awal musim). Sumber: Nutrient Cycling in Agroecosystems Volume 20, Number 3, 153-158. 14

Nilai Kritis K-tanah Nilai kritis K-tersedia pada tanah berpasir 46.2 mg/kg. Nilai kritis K-tersedia tanah berlempung 51.4mg/kg. Nilai kritis K-tersedia pada tanah liat 60 mg/kg. 15

Klasifikasi ketersediaan kalium tanah bagi tanaman tebu Texture Soil available) Increases yield K(mg/kg kg per K2O kg ( %) Sand Low <46 113 91 China 46- 90 >18 13.3 It is high> 90 - – Loam Low <52 109.2 >15 China 52- 110 88 10 It is high > 110 - – Clay Low <60 139.7 >10 China 60- 120 67.2 7.5 It is high > 120 < 8 < 5 16

SERAPAN KALIUM TANAMAN TEBU Setiap hektar tanaman tebu menyerap kalium sekitar 100.91-315.28 kg K2O. 2. Hasil tebu berkorelasi positif dengan serapan kalium (r = 0.979**) 3. Hasil tebu (y) berhubungan secara linear dengan serapan kalium (x) : y = 31687.1 + 246.0 x. 17

Aplikasi pupuk K pada tebu Tanaman tebu menyuerap kalium dalam jumlah yang lebih banyak dibandingkan dengan N dan P Penyerapan K paling banyak terjadi pada fase pertumbuhan awal dan pertengahan vegetatif. 18

Pengelolaan Kalium Tanaman Tebu harus memperhatikan hal-hal berikut: Nilai kritis K-tersedia dalam tanah, tanah pasir 46.2 mg/kg. Tanah lempung 51.4mg/kg; Tanah liat 60 mg/kg . Setiap hektar tanaman tebu menyerap sekitar 100.91-315.28 kg K2O atau setiap ton tebu menyerap K2O 1.98 - 2.71 kg. Efisiensi pemupukan kalium tanaman tebu 29.4 - 40.6%. Serapan kalium tanaman tebu pada berbagai fase pertumbuhan: Fase kecambah 4.2%, Fase pembentukan anakan 13.7%, Fase vegetatif awal 32.8%, Fase pertumbuhan lanjut 41.2%, Fase pemasakan 8.1%. Kecepatan penyerapan kalium pada fase pertumbuhan awal adalah 160 g/day/hm2 pda tanaman yang dipupuk NPK. Kecepatan penyerapan kalium pada fase pertumbuhan vegetatif sebesar 2180 g/day/hm2. Intensitas penyerapan kalium tanaman tebu dapat menurun menjadi 250 g/day/hm2 pada fase pemasakan. 19

The potassium cycle in the soil-plant-animal system (from SYERS, 1998) 20

Effect of K on sucrose content and sugar yield of cane in India (IPI on-farm trials, 2001) 21

Model Siklus Calvin yang disederhadnakan. Triose phosphates (TP) can either be exported to the cytosol for sucrose synthesis or stay in the chloroplast for starch synthesis; however, the bulk of TP is used for ribulose-1,5-bisphosphate (RuBP) regeneration. Sintesis sukose dalam cytosol is tergantung pada impor Pi oleh khloroplas. 22

MEKANISME PENYERAPAN K+ OLEH AKAR   Proses pertukaran kation antara akar tanaman dengan aprtikel tanah 23

Proses tidak langsung: PENYERAPAN KATION K+ Membran plasma sel-tanaman dapat menyerap ion dengan dua cara berbeda yang memerlukan energi: Metode tidak langsung, dimana pompa proton (hydrogen pumps) menciptakan gradien elektrokimia Metode langsung, dimana membran sel secara aktif mengangkut ion tertentu. Proses tidak langsung: Pompa Proton (hydrogen) dalam membran plasma memompa ke luar H+ dan selanjutnya hal ini akan mempunyai dampak ikuran seperti gambar berikut. 24

Penyerapan ion : METODE LANGSUNG   Ion K+ yang bebas dan ada dalam larutan tanah diambil secara aktif oleh pompa membran transport aktif. Pompa membran ini bersifat spesifik untuk setiap jenis kation. 25

. Fotoreduksi (reduksi FeIII cyanide) dan foto-fosforilasi dalam kloroplast merupakan fungsi dari konsnetrasi K+ (K1 = suplai K suboptimum, K2 = suplai K optimum) 26

Peranan K dalam sistem transpor nitrat dan malate dalam tanaman Peranan K dalam sistem transpor nitrat dan malate dalam tanaman. PEP= phosphoenol pyruvate (Marschner, 1995). 27

KALIUM MEMPERBAIKI RENDEMEN TEBU Aplikasi kalium meningkatkan hasil tebu dan rendemen pada tanah Andisols dan Entisols, kalau kandungan K-tanah kurang dari 102 ppm. Dosis optimum K2O sebesar 140 kg/ha dapat emningkatkan hasil gula sebesar 2.8 t/ha. Peningkatan hasil gula yang konsisten terjadi kalau pupuk Nk diaplikasikan pada Andisol yang miskin kalium. Hal ini berarti K dapat memperbaiki penggunaan N oleh tanaman dapat menjadi faktor pembatas untuk produksi gula. Tingkat kritis K-tanah adalah sekitar 102 ppm. Tanah-tanah dengan K-tanah lebih dari 140 ppm ternyata tidak respon terhadap pemupukan K. Sumber: Better Crops International Vol. 14, No. 1, May 2000 28

Sumber: Journal of Applied Sciences 7 (16): 2345-2350, 2007 PUPUK K DAN P RENDEMEN TEBU Aplikasi pupuk K dan P memperbaiki kualitas dan hasil tanaman tebu. Dosis yang diaplikasikan adalah potassium (0; 86 dan 172 kg/ha K2O) dan phosphorous (TSP) (0; 64.5 dan 129 kg/ha P2O5). Pupuk K dan P tidak meningkatkan kadar serat tebu; sedangkan kadar air tanaman dipengaruhi oleh pupuk K. Pupuk P meningkatkan kadar gula (polarization %) dan kemurnian nira tebu (°/u). Persen brix tebu menurun pada akhir musim sebagai respon thd pupuk P, sedangkan ratoon hanya sedikit terpengaruh. Sedangkan pupuk K tidak berpengaruh terhadap persen Brix, baik tebu-tanaman maupun ratoon. Sumber: Journal of Applied Sciences 7 (16): 2345-2350, 2007 29

APLIKASI PUPUK P & K TANAMAN TEBU Aplikasi pupuk P dan K berpengaruh terhadap hasil tanaman tebu. Dosis aplikasinya adalah (0, 72, dan 144 kg K/ha) dan (0, 29 dan 58 kg P/ha). Aplikasi kalium meningkatkan diameter batang, tinggi batang, hasil tebu dan hasil gula. Aplikasi pupuk P meningkatkan tinggi batang, jumlah ruas, hasil gula. Aplikasi P pada ratoon meningkatkan hasil tebu dan hasil gula. Kandungan K-tersedia dan P-tersedia dalam tanah menurun setelah panen tebu. Sumber: Journal of Plant Nutrition . Volume 27, Issue 4, 2004, Pages 663 - 699 30

DEFISIENSI K TEBU menghambat translokasi fotosintat Defisiensi K menghambat translokasi fotosintat dari daun ke bagian tanaman lainnya. Translokasi ini terhambat dalam helai daun yang tidak menunjukkan gejala defisiensi K dan tidak ada gejala penurunan fotosintesis. Pada kondisi defisiensi yang parah, laju fotosintesis dan konversi hasil fotosintesis menjadi hasil akhir akan terhambat. Laju respirasi daun yang defisien K juga mengalami peningkatan. Penurunan translokasi yang disebabkan oleh defisiensi K dianggap sebagai efek utama akibat dari munculnya gejala defisinesi kalium.. 31

Nilai kritis K-tanah yang ditetapkan melalui hasil kajian SASRI-FAS Persen Liat tanah kg K2O/ha ppm K 30% atau kurang 300 112 30% atau lebih 498 150 40% atau lebih 600 225 Rekomendasi dosis pupuk K : SASRI-FAS, 2002. Persen Liat Tanah Tanaman kg K2O/ha Kurang dari 30% Tebu Tanaman 90 - 210 Ratoon berikutnya 150 - 210 Lebih dari 30%, kecuali tanah yang KB nya tinggi 120 - 240 180 - 240 Lebih dari 40% liat dan kejenuhan basanya tinggi 120 - 300 240 - 300 32

Hubungan antara kandungan K-tukar dalam tanah dengan hasil relatif tebu (sumber: Farina et al., 1992). Farina, M.P.W., Channon, P., Thibaud, G.R. & Phipson, J.D. 1992. Soil and plant potassium optima for maize on a kaolinitic clay soil. S. Afr. J. Plant Soil 9, pp. 193 - 200. 33

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Potassium (K) is the most abundant cation accumulating in the cell sap of sugarcane plant. A healthy sugarcane crop indeed contains generally more than 200 kg K ha–1 in its aerial parts. Though in the absence of an adequate K supply, leaf area, tiller density and number of green leaves per mother shoot may not be affected, the height of millable stalks at harvest and to a lesser degree the number of stalks may be impaired. By acting mainly as an enzyme activator in plant metabolism, K is fundamental to the synthesis and translocation of sucrose from the leaves to the storage tissues in stalks. It also plays a significant role in controlling the hydration and osmotic concentration within the stomata guard cells. Responses of sugarcane to K fertilization reflect to a large extent the available K status of soil, significant responses being obtained only in soils low in available K. Evaluating the response of sugarcane to K fertilization must also take into account the semi-perennial nature of sugarcane plant. In this context as sugarcane is able to mine the soil of its K reserves, responses to K fertilizers are frequently not observed in plant cane and often even in first and second ratoons. The importance of a balanced nutrition particularly between nitrogen (N) and K in the attainment of the maximum yield should also not be overlooked. In general sugarcane responds to K fertilizers by an increase in cane yield without any change in sucrose concentration in the cane. As an excessive uptake of K by the sugarcane depresses the recovery of sucrose during milling, K fertilization of sugarcane must be kept just adequate to produce an optimum yield and to help regulate maturity so that maximum sugar is recovered from the millable canes. 34

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Sugarcane is capable of rapidly depleting soil of nutrients, particularly potassium. Under South African conditions, for instance, the aerial parts of an adequately fertilized 12 monthold rainfed plant cane crop has been reported to contain 214 kg K ha–1 (Wood, 1990). Under irrigation, a cane crop of similar age and variety may remove as much as 790 kg K ha–1. In the Histosols of Florida, an average of 343 kg K ha–1 was removed from the field at harvest of the sugarcane (Coale et al., 1993). In Mauritius, more than 250 kg K ha–1 was recovered by sugarcane from soils high in available K even when no K was applied (Cavalot et al., 1990). In Australia the average kg K ha–1 in the aboveground biomass of a crop of 84 tonnes cane ha–1 was 198 kg K ha–1 (Chapman, 1996). It is thus clear that for the long term and sustainable use of sugarcane lands, the removal of such large quantities of K needs to be balanced by adequate K inputs if a decline in soil fertility is to be avoided – hence the importance of K manuring in sugarcane cultivation. The effect which the K applied has on the growth, development, yield and quality of sugarcane is reviewed in this report. Cavalot, P.C., Deville, J. and Ng Kee Kwong, K.F. 1990. Potassium fertilization of sugarcane in relation to its availability in soils of Mauritius. Revue Agricole et Sucrière, Ile Maurice 69: 30-39. Chapman, L.S. 1996. Australian sugar industry by-products recycle plant nutrients. In : Downstream effects of land use (Ed. Hunter, H.M., Eyles, A.G. and Rayment, G.E.). Queensland Department of National Resources, Queensland, Australia. Coale, F.J., Sanchez, C.A., Izuno, F.T. and Bottcher, A.B. 1993. Nutrient accumulation and removal by sugarcane grown on Everglades Histosols. Agronomy Journal 85: 310-315. Wood, R.A. 1990. The roles of nitrogen, phosphorus and potassium in the production of sugarcane in South Africa. Fertilizer Research 26: 87-98. Diunduh dari: ………. 35

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius The crop is ratooned repeatedly until the yield declines to such an extent that replanting is worthwhile (up to nine ratoons may be grown in Mauritius). When grown at the 1.25 to 1.50 m interrow distance, sugar cane, depending upon the variety, needs 90 to 120 days to establish full ground cover. Establishment of sugarcane canopy in fact entails 2 overlapping processes: tillering (shoot population development) and leaf area formation. Leaf area development generally lags behind shoot population increases . Moreover it shows that in ratoon cane active absorption of K is out of phase with logarithmic synthesis of dry matter. Indeed most of the K needed by sugarcane will be taken up during shoot population development while dry matter accumulation will be most intense when maximum leaf area has been attained. Maximum leaf area in fact will coincide with the peak number of millable stalks rather than with total shoot number. The pattern of growth, growth rate, number of green leaves per mother shoot, leaf area and tiller density as described above have reportedly been found to be little affected by K manuring (Abayomi, 1981) unless there is a severe K deficiency (Chatterjee et al., 1998). Abayomi, A.Y. 1987. Growth, yield and crop quality performance of sugarcane cultivar Co 957 under different rates of application of nitrogen and potassium fertilizers. Journal of Agricultural Science 109: 285-292. Chatterjee, C., Nautiyal, N. and Dube, B.K. 1998. Effects of potassium concentration on biochemistry, yield and sucrose concentration in sugarcane. Sugar Cane 5: 12-15. 36

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Dry matter and K accumulation rates, tillers and leaf area formation in rainfed ratoon cane harvested in August and fertilized in September in Mauritius 37

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Effect of K manuring on height, stalk population and yields of sugarcane (Donaldson et al., 1990) Thus stalk height will generally be impaired by K deficiency while the effect on the number of millable stalks will not be significant (P = 0.05) unless K deficiency is severe (Chatterjee et al., 1998). Chatterjee, C., Nautiyal, N. and Dube, B.K. 1998. Effects of potassium concentration on biochemistry, yield and sucrose concentration in sugarcane. Sugar Cane 5: 12-15. Donaldson, R.A., Meyer, J.H. and Wood, R.A. 1990. Response to potassium by sugarcane grown on base saturated clay soils in the Eastern Transvaal lowland. Proceedings of the Annual Congress of South African Sugar Technologists Association 64: 17-21. 38

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Role of K in sugarcane Potassium, which is absorbed as K+, is the most abundant cation accumulating in the cell sap of sugarcane. The functions of K in sugarcane are many and have been extensively reviewed by Filho (1985). Among those functions which may be singled out is the main role of K as an enzyme activator in plant metabolisms such as in photosynthesis, protein synthesis, starch formation and translocation of proteins and sugars. With respect to the latter context, Humbert (1968) stated that while the downward movement of sugarcane from the leaves to the storage tissues in stalks proceeds at the rate of approximately 2.5 cm minute–1 in a well-fertilized sugarcane, a lack of K reduces the rate to below half that value. Therefore without an adequate K in the plant, some of the sugar may remain in the leaves instead of being transported, stored and harvested in the stalks. Furthermore if the K supply is inadequate, hydrolytic activity of invertase may be intensified resulting in cane with high reducing sugars but low sucrose level (Filho, 1985). Filho, J.O. 1985. Potassium nutrition of sugarcane. In : Potassium in agriculture. (Ed. Munson, R.D.). American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, Madison. pp 1045-1062. Humbert, R.P. 1968. The growing of sugarcane. Elsevier Publishing Co. Ltd, Amsterdam. 39

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Since K is a highly mobile nutrient in the plant, early symptoms of K deficiency are first seen in the older leaves. Leaf borders and tips will show yellow-orange chlorosis with numerous chlorotic spots that subsequently coalesce into brownish chlorotic blotches. This reduces the green leaf area in which photosynthesis takes place thereby depressing the growth of sugarcane. As rate of photosynthesis decreases with increasing severity of K deficiency, plant growth is retarded, internodes become shorter and the stalks themselves are shorter and smaller in diameter than those of well-fertilized sugarcane plants. Working with varieties H37-1933 and H50- 7209 Hartt and Burr (1967) found that K deficiency suppressed photosynthesis when the foliar K concentration fell to about 0.40 K% dry matter. Hartt, C.E and G.O Burr. 1967. Factors affecting photosynthesis in sugarcane. Proceedings of the Congress of the International Society of Sugar Cane Technologists 12: 510-609. Diunduh dari: ………. 40

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius The influencial role of K in the water economy of the sugar cane plant is also worth pointing out. Sudama et al. (1998) showed in pot experiments that application of K at time of planting under water stress conditions significantly increased the stomatal diffusive resistance, thereby decreasing transpiration rate and increasing the leaf water potential, cane length, sucrose content in juice and cane yield. Potassium is in fact reported to control the hydration and osmotic concentration of the stomata guard cells. When K is deficient it causes a loss of turgor pressure resulting in closing of the stomata and a reduction in the rate of transpiration and CO2 assimilation (Humbert, 1968). For sugarcane grown under moisture stress, application of extra K has even been reported to give higher cane and sugar yields (Filho, 1985). Filho, J.O. 1985. Potassium nutrition of sugarcane. In : Potassium in agriculture. (Ed. Munson, R.D.). American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, Madison. pp 1045-1062. Humbert, R.P. 1968. The growing of sugarcane. Elsevier Publishing Co. Ltd, Amsterdam. Sudama, S., Tiwari, T.N., Srivastava, R.P., Singh, G.P. and Singh, S. 1998 Effect of potassium on stomatal behaviour, yield and juice quality of sugarcane under moisture stress conditions. Indian Journal of Plant Physiology 3: 303- 305. 41

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Effects of K on sugarcane yields The yield components of sugarcane commonly measured are the millable stalk populations and cane fresh weight. In addition juice purity, sucrose concentration of the fresh cane stalk are determined to estimate recovery of sugar from milled cane. The effects of K on sugarcane yields particularly in Brazil and the rates of K used in different sugar-producing countries have been reviewed by Filho (1985) and Malavolta (1994). Sugarcane yield responses to K manuring are in fact very variable. Thus, Yang and Chen (1991) reported that only 33% of the sites studied in Fiji showed a response to K fertilization. Lakholine et al. (1979) showed in a 3-year study under Vidarbha conditions in India that there was no response to K applied at 50-100 kg K ha–1. Similarly Olalla et al. (1986) showed that at 0-300 kg K ha–1, there were no difference in cane and sugar yields at Malaga during the first 2 years of K fertilizer use and during the next 2 years when K fertilization was withheld. Prasad et al. (1996), on the other hand, found in a sandy loam calcareous soil of North Bihar that cane yield was increased from 50 t ha–1 without K fertilization to 74.5 t ha–1 with only 60 kg K ha–1. At 11 locations in Sao Paulo State of Brazil, Korndorfer (1990) indicated that raising application of K to 150 kg K ha–1 progressively increased cane yield. Korndorfer, G.H. 1990. Potassium and sugarcane quality. Informacoes Agronomicas 49: 1-3. Malavolta, E. 1994. Nutrient and fertilizer management in sugarcane. International Potash Institute Bulletin No. 14. International Potash Institute, Basel, Switzerland. Prasad, R., Prasad, U.S. and Sakal, R. 1996. Effect of potassium and sulfur on yield and quality of sugar cane grown in calcareous soils. Journal of Potassium Research 12: 29-38. Yang, S.J. and Chen, J.M. 1991. A review of fertilizer trials carried out by the Fiji Sugar Corporation between 1977 and 1987. Taiwan Sugar 38: 19-24. 42

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Available K in soil: The very variable response to K fertilization reported in field trials can to a large degree be explained by the availability of K in the soil. The studies on K fertilization of sugarcane in Mauritius, significant responses (at P = 0.05) in cane and sugar yields to K fertilizer were only observed in soils low in available K (<0.30 cmol kg–1 extractible in 0.1M H2SO4) while insignificant yield responses were found in soils with high available K (> 0.60 cmol kg–1 soil). These results are in agreement with observations of Humbert (1968) who found that above 0.23 cmol exchangeable K kg–1 soil in Hawaii, there was little likelihood of significant cane response to K fertilizers. Similarly in South Africa, Wood and Burrows (1980) recommended no K fertilization to the plant cane and to the next 4 ratoons when the soil exchangeable K exceeds 0.70 cmol kg–1. Humbert, R.P. 1962. Potash and sugarcane quality. Proceedings of the Congress of the International Society of Sugar Cane Technologists 11: 115-123. Humbert, R.P. 1968. The growing of sugarcane. Elsevier Publishing Co. Ltd, Amsterdam. Wood, R.A. and Burrows, J. R. 1980. Potassium availability in soils of the South African sugar belt. Proceedings of the Congress of the International Society of Sugar Cane Technologists 17: 182-195. 43

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Lack of sugarcane response to K fertilization however had also been reported even when available K in the soils was low. Thus Reis and Cabala-Rosand (1986) found no response to K fertilization even with available levels of this nutrient in the range of 0.07 to 0.14 cmol K kg–1. The frequent absence of yield response to fertilizer K in soils with low available K is an indication that under certain conditions, e.g. when K buffering capacity of the soil is high, sugarcane can acquire sufficient K from the non-exchangeable K reserves in the upper layers of the soil and from the sub-soil. Reis, E.L. and Cabala-Rosand, P. 1986. Response of sugar cane to nitrogen, phosphorus and potassium in the “Tabuleiros” soil of southern Bahia State, Brasil. Ravista Brasileira de Ciencia do Solo 10: 129-134. 44

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius The perennial nature of sugarcane plant: In addition to the availability of K in soils, the yield response of sugarcane to K fertilizers is influenced by the semi-perennial nature of the sugarcane crop. In fact the real benefits when sugar cane is grown depends on how many ratoons are possible. All those factors which affect its productivity, fertilizers included, should be studied over the whole cycle of the plant cane plus number of ratoons worthwhile before replanting. In this context, K already released by weathering together with K moved into the subsoil but returned to the surface layer during land preparation for replanting may be sufficient to meet the K requirements of the plant cane but not those of the subsequent ratoons. Sachan et al. (1993) also observed that plant cane crop did not respond to fertilizer K application while the first ratoon crop only did so slightly in a mollisol of Uttar Pradesh. Paneque et al. (1992) in Brazil reported that neither plant cane nor the first ratoon responded to K but cane yields increased by 23 and 39 t ha–1 at the end of the second and third ratoons, respectively. Paneque, V.M., Martinez, M.A,. and Gonzalez, P.J. 1992. Study of potassium levels in three sugarcane varieties grown on compacted red ferralitic soil. Cultivos Tropicales 13: 5-8. Sachan, R.S., Ram, N. and Gupta, R.A. 1993. Effect of soil and applied nitrogen, phosphorus and potassium on the yield of planted and ratoon crop of sugarcane in a Mollisol of Uttar Pradesh. Indian Sugar 42: 769-773. Diunduh dari: ………. 45

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Response of sugarcane to increasing rates of K in soils of Mauritius with low, medium and high available K as extracted in 0.1M H2SO4 46

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Response of sugarcane found from 1990 to 1993 at a site in Mauritius (Sans Souci) with only 0.16 cmol exchangeable K kg–1 Diunduh dari: ………. 47

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Sugarcane first ratoon response to K as affected by (A) P rates and (B) K rates in plant cane (Rodella, 1990) Rodella, A.A. 1990. Nutrient response relationships between ratoon and plant crops in sugar cane. Sugar Cane 1: 3-7. 48

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Importance of a balanced nutrition: Although no consistent statistically significant interaction has been shown to exist between N and K fertilization, a review of the literature shows that inputs of N and K must be balanced to optimize sugarcane production. For high yield (and good juice quality), K fertilizers are required in amounts equal to or greater than N (and P). In most sugarcane producing countries of the world, NPK ratios of 2:1:3 or 2:1:2 or 3:1:5 are commonly used (Wood, 1990). While N strongly stimulates growth, expansion of the crop canopy and interception of solar radiation (Milford et al., 2000) to primarily produce more millable cane, a large amount of K is needed as an osmotic solute to maintain the necessary cell turgor to drive this N-stimulated growth (Humbert, 1968). Fields with poor yields normally tend to have high N and critically low K levels resulting in high reducing sugars and low sucrose (Humbert, 1962). This statement serves to stress upon the necessity of having adequate K available to utilize unassimilated N in the ccane in order to bring about a stage of maturity where the reducing sugars are converted to sucrose. Milford, G.F.J., Armstrong, M.J., Jarvis, P.J., Houghton, B.J., Bellett-Travers, D.M., Jones, J. and Leigh, R.A. 2000. Effects of potassium fertilizer on the yield, quality and potassium offtake of sugar beet crops grown on soils of different potassium status. Journal of Agricultural Science 135: 1-10. Wood, R.A. 1990. The roles of nitrogen, phosphorus and potassium in the production of sugarcane in South Africa. Fertilizer Research 26: 87-98. 49

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Effect of K on sugarcane quality Improving cane quality is one of the most important means for maximising profitability in the sugarcane industry. It is indeed far more profitable to grind cane with a high percentage of recoverable sucrose as this will reduce the cost per unit tonne of sugar produced. In this respect juice quality is important as it determines the maximum sucrose yield. Unfortunately however sucrose content in cane is affected primarily by variety and climatic conditions and only in a relatively minor extent by the fertilizers applied. Though reports exist to indicate that K is capable of raising sugar yields without a concomitant increase in the yield of cane (see e.g. Dang and Verma, 1996), the majority of K fertilizer trials showed that a response to K in terms of cane yield was not accompanied by an increase of sucrose in the cane. Wood (1990) observed in South Africa that increasing the rate of K in the absence of a cane yield response had little effect on cane quality. Gulati et al. (1998) also observed in India that while K application in 2 equal splits (50% at sowing and 50% at end of monsoon) gave maximum cane yield and number of millable canes, juice quality was unaffected. Dang, Y.P. and Verma, K.S. 1996. Nutrient management in sugarcane in Haryana State : Key to improved sugar production. In : Sugar cane research towards efficient and sustainable production. (Ed. Wilson, J.R., Hogarth, D.M., Campbell, J.A. and Garside, A.L.). CSIRO Division of Tropical Crops and Pastures, Brisbane, Australia. pp 203-205. Gulati, J.M.L., Behera, A.K., Nanda, S. and Saheb, S.K. 1998. Response of sugarcane to potash. Indian Journal of Agronomy 43: 170-174. Wood, R.A. 1990. The roles of nitrogen, phosphorus and potassium in the production of sugarcane in South Africa. Fertilizer Research 26: 87-98. 50

The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius Most importantly, an excessive uptake of K from soil has been found to depress the recovery of sucrose during milling. As reviewed by Filho (1985), K has a tendency to increase sucrose solubility during sugar processing, thus maintaining a certain amount of sucrose in solution, one K+ tying up one molecule of sucrose. Wood (1990) noted a significant depression in sucrose concentration of cane following an application of 183 kg K ha–1 in South Africa. Chapman (1980) observed in long term trials in Australia that 196 kg K ha–1 slightly decreased sucrose content in cane when compared to the no K treatment. A more vivid example of K lowering sucrose recovery is provided by Korndorfer (1990) who observed that vinasse (distillery slops) when applied at 120 m3 ha–1 to a dark red dystrophic latosol in Brazil increased cane yield from 98 to 127 t ha–1 but decreased recoverable sucrose concentration in cane from 15.0 to 13.1%. Thus available data in the literature shows that K, in spite of its important role in sugarcane plant, must be kept just adequate to produce optimum yields and to regulate maturity so that maximum sugar is recovered from the millable stalks. Chapman, L.S. 1980. Long term responses in cane yields and soil analyses from potassium fertilizer. Proceedings of the 1980 Conference of the Australian Society of Sugar Cane Technologists: 63-68. Filho, J.O. 1985. Potassium nutrition of sugarcane. In : Potassium in agriculture. (Ed. Munson, R.D.). American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, Madison. pp 1045-1062. Korndorfer, G.H. 1990. Potassium and sugarcane quality. Informacoes Agronomicas 49: 1-3. Wood, R.A. 1990. The roles of nitrogen, phosphorus and potassium in the production of sugarcane in South Africa. Fertilizer Research 26: 87-98. 51

Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI Sugarcane is heavy feeder of K. The excess K in plant tissues interferes in sugar process due to scale formation in pans. Its demand may exceed 800 kg/ha. Agronomic value of K rests with increased cane volume, girth and weight per cane, drought and disease resistance and reduced lodging. In rations, K is essential to realize high yield and quality and response was more than for NP. Sources of K had no effect. A single basal dressing is desirable and response of K ranges from 0.01 to 0.352 t/ ha and 0.06 to 0.117 t /ha per kg K in plant and ratoons, respectively at optimum level. An array of extractants from dilute acids to alkalies have been tested but 1 N H2SO4 or 1M BaCl2 gives better prediction as it removes a portion of non-exch. K but plant available K known as STEP K. Recently, analysis of 100 year data from Rothamsted, UK have reported a strong relationship with exch. K & K balance. 52

Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI Sugar and starch crops require larger quantities of potassium than other crops. Its demand may exceed 800 kg/ha albeit this includes luxury consumption. According to Humbert (1968) a 100 ton crop on an average, removes 500 kg K2O/ha. An increased response is followed by optimum K concentration to luxury consumption and toxic levels. In fact, addition of K should be at response stage to reach an optimum level . Luxury consumption of K in the plant tissues interferes in sugar process due to scale formation in the pans. 53

Functions of potassium Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI Functions of potassium The functions of K are many. It is required for cells structure, carbon assimilation, photosynthesis, protein synthesis, starch formation, translocation of proteins and sugars and entry of water into plants. More than 60 enzymes are activated and it is basic to sugarcane for synthesis and accumulation of sugar (Clements, 1980). Important role in water relation is well recognized. Late K application (6 months) up to 50 kg K2O/ha is advocated to circumvent drought conditions. A foliar application of 2.0 to 2.5% K2O is advocated. But, there is practical difficulty in application as sugarcane attains a height of 2 to 3 m. Application of K is prophylactic measure against diseases like eyespot and cercospora. Lodging or layover of cane is greatly restricted due to K fertilization. Clements, H.F., 1980, Sugarcane crop logging and crop control: Principles and practices. The University Press of Hawaii, Honolulu, p. 520. 54

Agronomic value of potassium Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI Agronomic value of potassium Importance of K rests with improved girth and volume of cane (V = p x L x D x ¾, where L = cane length, in cm D = diameter cm). This is reflected in increased weight per cane with a consequent increase in yield. Other workers have reported increased population average height and dry matter (Thengavelu, 2009). Varietal differences were observed with regard to K uptake. Total K uptake was highest in Co7201 (502.1 kg/ha) and the lowest in Co 7712 (125.2 kg/ha). Thangavelu, S., 2009, Mineral nutrition in sugarcane crop production and improvement. Eds. Singh, S.B., Rao G.P., Soloman, S and Gopalesundaram P., Stadium Press LLC, Texas, USA, pp. 387- 488. 55

Effect of potassium on Fibre % and pol % cane (diagramatic) Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI Effect of potassium on Fibre % and pol % cane (diagramatic) It needs emphasis that K dressing has improved both fibre and pol per cent cane. It is postulated that fibre and pol are not negatively related. The possible reason is K improved fibre % by increasing sclerenchyma cells. Further, this nutrient has improved pol % juice by utilizing the N in the tissue. Rakkiappan (2002) has given target yield equations for two varieties : Co 8021 : FK = 3.621 T – 0.636 SK, Co 7219 : FK = 3.563 T – 0.694 SK. Rakkiappan, P., 2002, Soil fertility, nutrient uptake and micronutrient deficiencies in relation to varieties. Proc. Winter School on Sugarcane Breeding Gen. Retrospect Prospects, 21-22 November, 2002, Sugarcane Breeding Inst., Coimbatore, pp. 206-214. 56

Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI All sources of K are equally effective. Potassium scheonite (24% K2O) is as good as muriate/sulfate of potash (Hunsigi, 1993 and 2001). Potash is band placed in cane furrows below the set, but 3-5 cm away from it. Point placement /spot application even by peg method (Java method) to ratoon stools is advised. As regards time of application, it is mostly given as single basal application. However, split application in sandy soil is preferred. In PR China vast sugarcane fields are sprayed aerially with KCl (2.0 t 2.5 %) plus ethrel (500 to 1000 ppm) to improve cane and sugar yield. The recommended time of application to plant/ ratoon cane depends on edaphic /agro-ecological situations. Time of K application to sugar cane: Hunsigi, G., 1993, Production of sugarcane: Theory and practice Springer vertog, Berlin, Germany. Hunsigi, G, 2001, Sugarcane in Agriculture and Industry, Prism Book House, Bangalore, pp. 572. 57

Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI Soil K reaches the plant by mass flow / root extension and proliferation (effective soil volume) rather than by diffusion. All most all soil types respond to K addition save alluvial soils as they contain K bearing illitic clay and micas. Increased tonnage following K addition was observed more in red, mixed red and black soils of peninsular India. The application rates have ranged from 50 to 200 kg K2O/ha depending on soil types and agroecological situations. In a cropping system, as in sugar beet as intercrop or rotational crop, K addition ranges from 250-300 kg K2O/ha. In general, the response varies from 0.01 to 0.352 t/ha per Kg K2O in plant. Under rainfed condition response was around 0.27 t/ha per kg K2O. Potash yield relationship is better explained by second degree polynomial. Some potassium response equations in plant cane: 58

Karnataka J. Agric. Sci.,24 (1) : (45-47) 2011 Potassium management strategies to realize high yield and quality of sugarcane GURURAJ HUNSIGI Clements (1980) introduced the term crop log. Crop log, like a ship log, is a record of progress from the start until the arrival at harvest. Crop logging was successfully used to monitor, evaluate or schedule fertilizer application to maximize crop production. There is an opportunity for mid term correction. Sheath moisture index (3-6 leaf sheaths) is accepted as a single parameter, which predicts plant performance. It is intriguing that crop log data is rarely adopted in Indian sugar factories. In recent times foliar diagnostic approach is contested. But, soil test remains an excellent pre-plant practice and critical nutrient level (CNL) is a good guide for scheduling fertilizer application to plant crop. Table 2 presents critical nutrient levels for sugarcane (Clements, 1980). Clements, H.F., 1980, Sugarcane crop logging and crop control: Principles and practices. The University Press of Hawaii, Honolulu, p. 520. 59

Potassium management for sugarcane on base saturated Proceedings of the Australian Society of Sugar Cane Technologists 31: 186-194. (2009) Potassium management for sugarcane on base saturated soils in northern New South Wales. Kingston G, Anink M C, Clift B M, Beattie R AN industry-wide survey of the nutrient status of sugarcane crops in 2000–01 showed leaf potassium (K) levels in most samples from New South Wales were well below the critical value. There were no data to indicate the significance of this information for crop yield and future K management. In 2002, rates of K fertiliser experiments were established at two sites in the Broadwater Mill area on clay soils where exchangeable K was 0.13–0.14 cmol(+)/kg and nitric K was 0.78–1.04 cmol(+)/kg. Calcium (Ca) + magnesium (Mg) saturation was 91–95% of total bases. The lowest rates of applied K were the growers’ strategy of 39 and 42 kg K/ha. Treatments of 0 to an additional 300 kg K/ha were applied in 50 kg increments as row dressings. Five crops were harvested between 2003 and 2005. Leaf K% was always below the critical value in the standard treatment, and above the critical value for some of the higher rates of K in 2003 and 2005. There was no yield response to K fertiliser above the basal rate indicating supply of K from non-exchangeable soil reserves was adequate. Biomass K increased with rate of applied K, but the K balance was negative when less than 192 kg K/ha was applied. Leaf data suggested high levels of (Ca+Mg) in soil may be interfering with K uptake. The ratio of (Ca+Mg)/K >0.55 can be used to identify leaf samples from base saturated soils that may require interpretation using a reduced critical value in the range 0.75–0.9% K. Absence of yield responses showed that the crop does not need more K than is currently applied, but soil K status should be monitored to indicate when potential for yield response should be re-evaluated. Diunduh dari: ………. www.bses.com.au/.../146355_Potassium_management_for_sugarcan... 60

Journal of Agronomy and Crop Science 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 2009 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: ………. http://onlinelibrary.wiley.com/doi/10.1111/j.1439-037X.2009.00364.x/abstract 61

Diunduh dari: ………http://www.publish.csiro.au/paper/SP02004.htm. Potassium Studies on Some Sugarcane Growing Soils in Fiji J.S. Gawander, P. Gangaiya and R.J. Morrison The South Pacific Journal of Natural Science 20(1) 15 - 21 This study investigated the potassium (K) status of sugarcane growing soils in Fiji, using samples taken from fields under cultivation and also from sites that had not been cultivated for at least 30 years. Five sites were on highly weathered oxyhydroxide soils where the total K contents and K retention capacities were generally low. The two less weathered soils containing significant amounts of 2:1 expanding clay minerals had much higher total K and non-exchangeable K. Exchangeable K and soil solution K contents varied significantly, but were generally low for most soils. Exchangeable K contents were lower in the regularly cultivated fields at five sites out of the eight, were higher at 2 sites, while for one site there was no change. These variations may be due to different levels of K input, uptake by crop and losses due to leaching and erosion. The two less weathered soils (Sigatoka and Nawaicoba) had lower contents of both non-exchangeable and exchangeable K in the cultivated soil when compared with the fallow sites suggesting net loss of K due to cultivation. These soils, however, also had high surface negative charge and thus a better capacity to retain K. Since the K requirement of sugarcane is characteristically high and large amounts of K are removed in the harvested crop, K fertilizer practices need to be scrutinized carefully in Fiji. Diunduh dari: ………http://www.publish.csiro.au/paper/SP02004.htm. 62

Amir Bostani, Gholam Reza Savaghebi & Mohammad Miransari . Communications in Soil Science and Plant Analysis . Volume 42, Issue 16, 2011 .pages 2024-2037 Potassium Behavior in Some Iranian Soils of Khuzestan Province Planted with Sugarcane Amir Bostani, Gholam Reza Savaghebi & Mohammad Miransari Effects of potassium (K) fertilization, cropping history, and soil mineralogy on K fixation and availability were investigated in three sugarcane development projects. Hence, water-soluble, exchangeable, nonexchangeable, and available K (sum of water-soluble and exchangeable) was evaluated in the three projects including Haft-Tapeh (H), Karun (Ka), and Sugarcane Development Project (T) with 41, 26, and 8 years of sugarcane plantation, respectively, in the Iranian soils of Khuzestan province. According to the results, K fixation ranged from 17.74 to 129.15 mg kg−1 and with increasing K levels, its amounts and percentage (P = 0.01) increased. With less than 30 years of plantation, there were not any differences in different plantation histories with regard to K fixation and availability. Evaluation of K dynamic based on long-term experiments can effectively contribute to the determination of appropriate rates of K fertilization for sugarcane production. Diunduh dari: ………. http://www.tandfonline.com/doi/abs/10.1080/00103624.2011.591643 63

A Classification System for Potassium Availability in Soils for Sugarcane Planting Regions in Guangxi Tan Hongwei, Zhou Liuqiang, Xie Rulin, Huang Meifu Guangxi Sciences [2003, 10(4):321-324] From 1991 to 2001,82 field experiments were carried out on sugarcane in Laibin,Hepu,Guigang and Bobai Crop response to K as affected by the K status (available K) was measured and statistically analysed Calculated critical values depended on the soil texture,characterised by sands,loam soils and clays For sugar cane cultivated on all three soil textures,the calculated critical K values were,46 2,51 2 and 60 mg/kg of available K in sandy,loamy and clayey soils,respectively Accordingly, potassium supply classes for soils of cultivating sugar cane were established For the three soil textures, the following supply classes were defined: (1) Low K supply: <46 mg/kg,<52 mg/kg and <60 mg/kg, (2) Medium K supply: 46~90 mg/kg, 52~110 mg/kg and 60~120 mg/kg. Diunduh dari: ………. http://europepmc.org/abstract/CBA/549791 64

FOLIAR DIAGNOSIS OF SUGARCANE - VARIATION OF lEAF . Proceedings of The South African Sugar Technologists' Association - June 1990 FOLIAR DIAGNOSIS OF SUGARCANE - VARIATION OF lEAF POTASSIUM VALUE WITH AGE OF CANE AND RAINFALL REGIME K. F. NG. KEE KWONG, GAUTHIER and J. DEVILLE Sugar Industry Research Institute, Reduit, Mauritius The top visible dewlap leaf potassium (K) of sugarcane ratoons varies in an irregular manner with age ofcane. However, by increasing the number of leaf samplings, the fluctuation ofthe mean K values with age becomes less and less significant. As a result in Mauritius, where the running average leaf K concentration of 3 consecutive years of double leaf sampling is interpreted, age corrections of the analytical leaf K value will not have a noteworthy impact on the accuracy of foliar diagnosis for K status. Examination of daily rainfall which fell 30 days prior to leaf sampling failed to reveal the exact significance of moisture regime on the K nutritional status of sugarcane. In some instances a high rainfall prior to leaf sampling gave rise to a high leaf K value, while in other instances at the same site the opposite was true. Diunduh dari: ………http://www.sasta.co.za/wp-content/uploads/Proceedings/1990s/1990_Kwong_Foliar%20Diagnosis%20Of%20Sugarcane.pdf. 65

FOLIAR DIAGNOSIS OF SUGARCANE - VARIATION OF lEAF . Proceedings of The South African Sugar Technologists' Association - June 1990 FOLIAR DIAGNOSIS OF SUGARCANE - VARIATION OF lEAF POTASSIUM VALUE WITH AGE OF CANE AND RAINFALL REGIME K. F. NG. KEE KWONG, GAUTHIER and J. DEVILLE Sugar Industry Research Institute, Reduit, Mauritius The practice of foliar diagnosis using the threshold value concept to monitor the nutrient status of sugarcane fields in Mauritius has been reviewed by Ng Kee Kwong et al. (1988). Its accuracy is impeded by the variation of the top visible dewlap (TVD) leaf nutrient level with age ofcane. To overcome this drawback, the TVD leaf" of sugarcane aged from three to seven months may be sampled in the absence of moisture stress, and age corrections are then applied to the leaf nutrient values to bring them to the standardized age of five months. Since leaf nitrogen (N) and phosphorus (P) concentrations decrease consistently with age of cane (Ng Kee Kwong et al. 1988), the magnitude of the age corrections for these two elements can be established with reliability. The leaf potassium (K) level, however, varies in an irregular manner with age of cane and consequently no reliable age correction can yet be applied to the analytical leaf K values. Ng Kee Kwong, KF, Gauthier, J and Deville,J (1988). Foliar diagnosis of sugarcane in Mauritius - a historical review. Sugar cane (Spring supplement): 1-7. Diunduh dari: ………http://www.sasta.co.za/wp-content/uploads/Proceedings/1990s/1990_Kwong_Foliar%20Diagnosis%20Of%20Sugarcane.pdf. 66

FOLIAR DIAGNOSIS OF SUGARCANE - VARIATION OF lEAF . Proceedings of The South African Sugar Technologists' Association - June 1990 FOLIAR DIAGNOSIS OF SUGARCANE - VARIATION OF lEAF POTASSIUM VALUE WITH AGE OF CANE AND RAINFALL REGIME K. F. NG. KEE KWONG, GAUTHIER and J. DEVILLE Sugar Industry Research Institute, Reduit, Mauritius The cause of the irregular variation of leaf K with age of cane is not known with certainty. It has, however, been shown that K availability, uptake by plants and crop response to K fertilizers are influenced by the moisture regime (Krishnakumari et al. 1988 , Kuchenbuch et al. 1986, Mengel and Von Braunschweig, 1972). In addition K uptake by the plant is believed to be more sensitive than uptake of other nutrients to changes in soil moisture (Wood and Meyer, 1986). Existing information in the literature thus points towards the fluctuation in water regime as a factor which may be causing leaf K concentration to vary irregularly with age of cane. Krishnakumari, M, Bajaj, JC and Wahid-U-Zzaman (1988). Effect of interactions of different levels of soil moisture and potassium on the dry matter production and potassium uptake by Hordeum vulgare (barley) in different soils. Plant Soil 109: 294-296. Kuchenbuch, R, Claassen, Nand Jung, KA (1986). Potassium availability in relation to soil moisture.I. Effect of soil moisture on potassium diffusion, root growthand potassium uptake of onion plants. Plant Soil 95: 221-231. Mengel, Kand VonBraunschweig, LC. (I972). The effect of soilmoisture upon the availability of potassium and its influence on the growth of young maize plants (Zea mays L). Soil Sci 114: 142-148. Wood,RA and Meyer, JH (1986). Factorsaffecting potassium nutrition of sugarcane in South Africa. Proc S Afr Sug Technol Ass 60: 198-204. Diunduh dari: ………http://www.sasta.co.za/wp-content/uploads/Proceedings/1990s/1990_Kwong_Foliar%20Diagnosis%20Of%20Sugarcane.pdf. 67

. Proceedings of The South African Sugar Technologists' Association - June 1990 FOLIAR DIAGNOSIS OF SUGARCANE - VARIATION OF lEAF POTASSIUM VALUE WITH AGE OF CANE AND RAINFALL REGIME K. F. NG. KEE KWONG, GAUTHIER and J. DEVILLE Sugar Industry Research Institute, Reduit, Mauritius Average variation of top visible dewlap (TVD) leaf K with age of sugarcane varieties M 13/56 and M 377 /56. Diunduh dari: ………http://www.sasta.co.za/wp-content/uploads/Proceedings/1990s/1990_Kwong_Foliar%20Diagnosis%20Of%20Sugarcane.pdf. 68

George Samuels and Pablo Landrau The Influence of Potassium on the Yield and Sucrose Content of Sugarcane George Samuels and Pablo Landrau SSSAJ. 1955. Vol. 19 No. 1, p. 66-69 The results of over 200 field experiments with potash fertilizers on sugarcane conducted by the Agricultural Experiment Station of the University of Puerto Rico over a wide range of cane varieties and soils of Puerto Rico were analyzed with respect to the influence of the potash on cane yields and sucrose content. The results indicated that potash increased yields mainly on the red and yellow podzolic soils of the humid area and in a planosal of the semi-arid area. The irrigated cane areas showed slight if any response to potash. The use of potash increased sucrose concentrations in the cane only if cane yields were also increased. Increases of 10% or more in cane tonnage were needed for increases in sucrose. When potassium fertilizer significantly influenced sucrose concentration, this was accomplished mainly by raising the polarization value of the cane juice. Percent Brix and extraction were not appreciably influenced. The use of foliar diagnosis proved to be of great value in determining when to apply potash fertilizers to cane. Leaf values of 2.00% or more on a dry-weight basis indicated no expected potash responses for all soils and cane varieties in Puerto Rico. In humid areas, leaf values below 1.80% indicated that a response to potash fertilizers could be expected. Diunduh dari: ……https://www.soils.org/publications/sssaj/abstracts/19/1/SS0190010066?access=0&view=pdf…. 69

Growth, yield and crop quality performance of sugarcane cultivar Co 957 under different rates of application of nitrogen and potassium fertilizers A. Y. ABAYOMI. J. Agric. Sci,.,Camb.( 1987),1 09, 285-292 Screen house and field experiments at the Sugar Research Institute, University of Ilorin, Nigeria were carried out to evaluate the effects of various amounts of nitrogen and potassium fertilizers singly and in combinations on growth, yield and crop quality of sugarcane cultivar Co 957. Growth rate, number of green leaves per mother shoot, leaf area, plant height, stalk length and tiller density were significantly affected by nitrogen application but were not significantly affected by potassium. Similarly, cane tonnage was significantly affected by nitrogen but not by potassium. In the screen house trial, responses to N were linear from 0 to 160 kg N/ha. However, in the field, while the measured variables also increased linearly with N application from 0 to 160 kg N/ha, they decreased at 200 kg N/ha. Cane quality decreased with increased nitrogen and potassium. However, these reductions were significant' only at the highest level of nitrogen and potassium. There were no significant nitrogen and potassium interactions on any of the variables studied. Diunduh dari: ………http://unilorin.edu.ng/publications/abayomiya/Growth,%20Yield%20and%20Crop%20Quality%20Performance%20of%20Sugarcane%20Cult.PDF. 70

Growth, yield and crop quality performance of sugarcane cultivar Co 957 under different rates of application of nitrogen and potassium fertilizers A. Y. ABAYOMI. J. Agric. Sci,.,Camb.( 1987),1 09, 285-292 In studies of the physiology of cane plants, emphasis has been placed on growth as controlled by nutrition, water relationships and climatic factors well as sucrose formation and storaqe. Much has been reported elsewhere on the effects of the major elements, nitrogen, phosphorus and potassium as well as irrigation on the yield of cane and sugar (Azeredo, Robina & Manhales, 1980; Castellanos, Gerret & Lopez, 1978; Castellanos el al. 1980; Clements, 1964a, b, 1970, 1980; Chaudhry, 1983; Gascho & Kidder, 1979; Le Grand, Burdine & Thomas, 1961 ; Samuels, Hugo-Lopez & Landrau, 1952). These reports are diverse especially on the effects of nitrogen and potassium on cane tonnage, juice quality and the consequent commercial sugar production. Azeredo,D . F. De, Robina, A . A. & M.S. Manhales. (1980). Mineral fertilizing (NPK) of plant cane in the States of Rio de Janeiro and Minas Garais Plana / sucar (Brazil) 95, 19-28. Chaudury, B. A. (1983). Low sugarcane productivity in Negros - Why ? Sugarland. 20 (6), 4-7. Diunduh dari: ………http://unilorin.edu.ng/publications/abayomiya/Growth,%20Yield%20and%20Crop%20Quality%20Performance%20of%20Sugarcane%20Cult.PDF. 71

Growth, yield and crop quality performance of sugarcane cultivar Co 957 under different rates of application of nitrogen and potassium fertilizers A. Y. ABAYOMI. J. Agric. Sci,.,Camb.( 1987),1 09, 285-292 Plant growth characters such as growth rate, plant height and stalk length, stalk thickness, number of green leaves per mother shoot, leaf area and number of tillers did not show appreciable effect due to potassium, except that growth rate at the first 6 weeks (trial 1, Table 2) and number of tillers at 16 weeks after planting (trial 2, Table 4) were significantly increased and reduced respectively by all levels of applied K. However, Humbert (1968) indicated the importance ofthe effect ofK on early growth characters. He reported that with adequate K, senescence of older leaves is delayed, resulting in a greater total leaf area from an increase in both number and size of leaves. Similarly, stalk diarneter and the number of tillers were increased with potash application (Borden, 1937 and Degade, 1976). But in consonance with the observations in the present studies, Gregory & Baptiste (1936) found that the number of leaves produced on the main shoot of barley was independent of K supply. Degade, V.G.1976. Effect of potassium fertilization on yield and quality of sugarcane. Indian Sugar 26 (4), 95-197 Gregory,F.G. & E.C.D. Baptiste . (1936). Physiological studies in plant nutrition V. Carbohydrate metabolism in relation to nutrient deficiency and to age in leaves of barley. Annls of Botany 50, 579. Diunduh dari: ………http://unilorin.edu.ng/publications/abayomiya/Growth,%20Yield%20and%20Crop%20Quality%20Performance%20of%20Sugarcane%20Cult.PDF. 72

Growth, yield and crop quality performance of sugarcane cultivar Co 957 under different rates of application of nitrogen and potassium fertilizers A. Y. ABAYOMI. J. Agric. Sci,.,Camb.( 1987),1 09, 285-292 Similar to the effects of N on crop quality, the percentage dry matter and percentage sugar in juice were both reduced with increase in potassium application. These reductions were, however, significant only at the highest levels where the least percentage dry matter and percentage sugar in juice were obtained. This is in contrast to the results of other workers who showed that potash applications improved cane quality (Borden, 1937; Innes, 1959; Innes & Chinloy, 1953; Azeredo et al. l98O) Azeredo,D . F. De, Robina, A . A. & M.S. Manhales. (1980). Mineral fertilizing (NPK) of plant cane in the States of Rio de Janeiro and Minas Garais Plana / sucar (Brazil) 95, 19-28. Borden, R.J. (1937). Cane growth studies.The effect of sunlight on the utilization of nitrogen and potash by H 109 cane. Hawaiian Planters' Record,41:3-5. Innes, R,. F. (1959) The potash manuring of sugarcane. Proceedings of the 10th Congress of the International Society of Sugarcane Technologists, pp 441-45O. Innes, R.F. & T.Chinloy. (1953). The effects of fertilizers on sugarcane I. Potash Jamaica Association of Sugar Technologists Journal 15, 1. Diunduh dari: ………http://unilorin.edu.ng/publications/abayomiya/Growth,%20Yield%20and%20Crop%20Quality%20Performance%20of%20Sugarcane%20Cult.PDF. 73

Timing potassium fertilizer applications to sugarcane in Mauritius Fertilizer research October 1989, Volume 20, Issue 3, pp 153-158 Timing potassium fertilizer applications to sugarcane in Mauritius K. F. Ng Kee Kwong, J. Deville The influence of K fertilizer timing on yield and K nutrition of sugarcane (Saccharum hybrid sp.) was investigated by field experiments in Mauritius. The data obtained showed that delaying all or half of the recommended 150 Kg K/ha to coincide with the peak growth period of sugarcane had no significant bearing on the yield and K nutritional status of the sugarcane. In areas with an annual rainfall less than 2000 mm per year, the K requirement of as many as 6 sugarcane crops could be met by a single application of K fertilizer banded in the rows at planting. However in regions where rainfall exceeds 2000 mm per year, yearly application of the required K is preferable to a large single application of K fertilizer at planting. Diunduh dari: ………. http://link.springer.com/article/10.1007%2FBF01054550?LI=true 74

Plant Physiol. 1969 October; 44(10): 1461–1469. Effect of Potassium Deficiency Upon Translocation of 14C in Attached Blades and Entire Plants of Sugarcane. Constance E. Hartt. A deficiency in potassium decreased the translocation of labeled photosynthate from the leaf to the rest of the plant. Translocation was inhibited in blades which exhibited no visible symptoms of potassium deficiency and in which no decrease in photosynthesis was detected. In more severe deficiency both the rate of photosynthesis and the conversion of intermediates to end products decreased. The rate of respiration in deficient blades increased. The decrease in translocation caused by potassium deficiency is considered to be a primary effect and not secondary to the development of the well-known symptoms of potassium deficiency. Diunduh dari: ………. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC396287/pdf/plntphys00215-0090.pdf 75

Plant Physiol. 1969 October; 44(10): 1461–1469. Effect of Potassium Deficiency Upon Translocation of 14C in Attached Blades and Entire Plants of Sugarcane. Constance E. Hartt. It is generallv accepted that a relationship exists between potassium and the translocation of photosynthate. The evidence that potassium increases translocation of photosvnthate, however, is not unan.mous, as shown by Thomas (38). In the era before radioactive carbon, several lines of investigation suggest'ed that K deficiency decreases translocation (1, 6, 8, 30, 32,33). In sugarcane plants deficient in K, a necrosis of the phloem. which might decrease trans!ocation, was noted (9, 10). Others have reported no effect of K upon tranlocation (31. 35). Tincker and Darbishire (39) reported that K did not appear to aid translocation except in nmoderate light. James (26) could not definitely show an effect of K upon translocation. but suggested that K accelerated trans!ocation. Gauclh (7) cautioned that the accumulation of carbohydrates of an associated with K and other deficiencies may be only the indirect effect of the deficiency with no direct connection between the element and translocation of carbohydrates. Many linies of evidence are needed to establish a causal relationship between an element and carbohydrate transport, according to Gauch. ABUTALYDOV, M. G. AND S. PRAKTTMANOVA. 1965.. The effcct of pholsphorus, magnesiunm. Potassium and calcium oln the cut-la)\w of sugars from the leaves and their transport along the cortex of the stem. (in Russian). Akad. 'Nauk Azerbaidzh. SSR, Baku. lzvestiia, Ser. Biol. Naukl 1: 3-14. (Biol. Abs. 48: 93 7. 1967). GAUCH. H. G. 1977. MineIral nutrition of plants. Ann. Rev. Plant Physi 1. 8: 31-64. 26. JAMES, W.O. 1930. Studies of the physiological importance of the mineal elemients in plants. 1. The relation of potassium to the properties and functions of the leaf. AnnI. Botany 44: 173-93. Diunduh dari: ………. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC396287/pdf/plntphys00215-0090.pdf 76

Plant Physiol. 1969 October; 44(10): 1461–1469. Effect of Potassium Deficiency Upon Translocation of 14C in Attached Blades and Entire Plants of Sugarcane. Constance E. Hartt. Effect of K upon loss of 14C from the fed part. Plants of variety H 38-2915, age 8.5 months, had been grown in solutions for 5.5 months. Condition of plants at time of experiment: +K, vigorous, and green; -K, leaves burned at tip and edges, and pale green. Diunduh dari: ………. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC396287/pdf/plntphys00215-0090.pdf 77

Plant Physiol. 1969 October; 44(10): 1461–1469. Effect of Potassium Deficiency Upon Translocation of 14C in Attached Blades and Entire Plants of Sugarcane. Constance E. Hartt. Effect of K upon translocation from the fed part, with the first translocation interval shortened to 1.5 or 2 hr. (A) 24-hr test of variety H 50-7209, aged 6.7 months and grown in solutions for 3.2 months. Condition of fed blade: +K, good green; -K, good green but with narrow brown edges and dry at the tip. 14CO, (10 uc) was fed to a 20 cm length of blade 7. Diunduh dari: ………. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC396287/pdf/plntphys00215-0090.pdf 78

Plant Physiol. 1969 October; 44(10): 1461–1469. Effect of Potassium Deficiency Upon Translocation of 14C in Attached Blades and Entire Plants of Sugarcane. Constance E. Hartt. Effect of K upon translocatiofn down the blade; translocation period was 30 min. Data concerning symptoms and feeding are reported in the legend to table II. Plants had been grown in + and - K solutions for 3 months. Velocity, cm per min: +K, 1.4; -K, 0.7. (Velocity of +K measured at shorter intervals - 2.0 to 2.5 cm per min.) Diunduh dari: ………. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC396287/pdf/plntphys00215-0090.pdf 79

Plant Physiol. 1969 October; 44(10): 1461–1469. Effect of Potassium Deficiency Upon Translocation of 14C in Attached Blades and Entire Plants of Sugarcane. Constance E. Hartt. Diunduh dari: ………. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC396287/pdf/plntphys00215-0090.pdf 80

Refining foliar diagnosis of potassium status of sugar cane - defining site - specific optimum leaf potassium levels. Ng Kee Kwong, K. F.; Chong Shin Sen, P. Revue Agricole et Sucrière de l'Île Maurice. 2000 Vol. 79 No. 1 pp. 36-41 As sugar cane response to potassium (K) fertilization is influenced by environmental factors such as moisture, a single optimum leaf K concentration cannot be valid for all locations in Mauritius. Consequently, the optimum leaf K concentration specific to the main soil families in each factory area has been established by the boundary line approach using the yield and leaf K data sets collected since 1989 from the permanent sampling units (PSUs). The results obtained showed that the location-specific optimum leaf K concentration covered the narrow range of 1.00 to 1.30 K% d.m. with most of the values being restricted between 1.10 to 1.30 K% d.m. In view of the variability introduced during field sampling of the leaves, and during laboratory analysis together with the uncertainty caused by the irregular variation of leaf K concentration with age of sugar cane, a single optimum leaf K level of 1.20% d.m. can continue to be used for the diagnosis of K status of sugar cane in Mauritius except in the M2, T3/T4, L4 soil families as well as in the P1 soils of Médine factory area and in P2 soils of Mon Trésor factory area. In these soil families an optimum leaf K concentration of 1.00% d.m. will more accurately reflect the K status of sugar cane thereby avoiding overfertilization with K fertilizers. Diunduh dari: ………http://www.cabdirect.org/abstracts/20013077169.html. 81

Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. EFFECT OF K2O LEVELS AND ITS APPLICATION TIME ON GROWTH AND YIELD OF SUGARCANE Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. J. Agric. Res., 2010, 48(3). 315-325 In a study conducted at Sugarcane Research Institute, AARI, Faisalabad, Pakistan during the year 2006 and 2007, four K2O levels (0, 112, 168 and 224 kg/ha) were applied to sugarcane crop at three different times i.e. at sowing, 90 days after sowing (DAS) and half at sowing + half at 90 DAS. Layout system was RCBD with three replications having a net plot size of 6 x 8 meter. The results revealed significant differences among all treatment means except germination percentage and number of shoots. K2O @ 168 kg in two splits; half at sowing + half at 90 DAS produced maximum cane length (305 and 290 cm), number of millable canes (13.0 and 12.7/m2) and stripped cane yield (116 and 107 tons/ha). during the year 2006 and 2007, respectively. A positive and strong relationship was observed between stripped cane yield and number of shoots, cane length, cane girth and number of millable canes. Diunduh dari: ………. http://www.jar.com.pk/admin/upload/34__315Paper-No.5.pdf 82

Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. EFFECT OF K2O LEVELS AND ITS APPLICATION TIME ON GROWTH AND YIELD OF SUGARCANE Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. J. Agric. Res., 2010, 48(3). 315-325 Sugarcane (Saccharum officinarum L.) is one of the important cash crops of Pakistan. It is grown on an area of 1.241 million hectares with a total annual stripped cane production of 63.92 million tons with an average stripped cane yield of 51.51 tons per hectare. Important factors responsible for low yield of sugarcane in Pakistan include scarcity of irrigation water, low plant population per unit area and untimely, imbalanced as well as inadequate use of fertilizers especially K2O. Sugarcane is a long duration and exhaustive crop that requires high quantity of nutrients heavily. Sugarcane production of 100 tons per hectare removes 207 kg N, 30 kg P2O5 and 233 kg K2O from the soil (11). Therefore, these elements must be present in adequate quantities in the root zone of crop for attaining higher yield. A big gap exists between attainable cane yield potential (300 t/ha) and average national harvested yield (49 t/ha) of existing cane varieties (17). The growth and yield of sugarcane primarily depends on fertility status of the soil, climate, genetic potential of cultivars and proper management of the crop including application of fertilizer at appropriate rate and time. 11. Jagtap, S. M., M. B. Jadhav and R. V. Kulkarni. 2006. Effect of levels of NPK on yield and quality of suru sugarcane (cv. Co. 7527). Indian Sugar. 56 (7): 35-40. 17. Majid, A. 2007. Sugarcane variety composition in Pakistan. Pak. Sug. J. 22 (2): 2-21. Diunduh dari: ………. http://www.jar.com.pk/admin/upload/34__315Paper-No.5.pdf 83

Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. EFFECT OF K2O LEVELS AND ITS APPLICATION TIME ON GROWTH AND YIELD OF SUGARCANE Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. J. Agric. Res., 2010, 48(3). 315-325 Number of tillers The data on number of tillers also showed non-significant effect of K2O levels and its time of application. However, maximum number of tillers (19.7 and 20.1/m2 during year 2006 and 2007) were recorded in T7 (84 kg K2O/ha at sowing + 84 kg K2O/ha at 90 DAS) against minimum (16.5/m2 during 2006 and 16.6/m2 during 2007) in T1. The year effect on number of tillers was also non-significant. Significantly maximum number of tillers per square meter was observed by Rathore et al. (21) at higher dose of 100 kg K2O applied in two splits. Similarly Bokhtiar et al. (8) and Jeyaraman and Alagudurai (12) recorded significant effect of different K2O rates and noted maximum number of tillers upto 160 and 132.5 kg K2O per hectare, respectively. In present study similar number of tillers was produced during both years. These results are in accordance with those of previous workers (6, 9, 18) who also found non-significant effect of different K2O levels on number of tillers. The correlation analysis showed a strong and positive association between number of shoots and stripped cane yield during both years. It was also supported by regression model which indicated the dependence of stripped cane yield on number of tillers. 6. Aslam, M. and A. A. Chattha. 2005. Contribution of potash in increasing sugarcane productivity. Pak. Sug. J. 20 (1): 6-8. 8. Bokhtiar, S. M., G. C. Paul, A. B. M. Mafizur Rahman and M. M. Alam. 2002. Response of NPK and S on the growth and yield of sugarcane grown in the calcareous dark grey floodplain soils of Bangladesh. Pak. Sug. J. 17 (1): 16-21. 9. Gawander, J. S., P. Gangaiya and R. J. Morrison. 2004. Potassium responses and budgets in the growth of sugarcane in Fiji. Sugar Int. 22 (1): 3-8. 12. Jeyaraman, S. and S. Alagudurai. 2003. Nitrogen and potassium management for yield maximization in sugarcane. Indian Sugar. 52 (12): 987-989. 18. Patel, M. L., D. R. Delvadia, L. N. Bariya and R. A. Patel. 2004. Influence of nitrogen, phosphorus and potash on growth, quality, yield and economics of sugarcane cv. CO-N-91132 in middle Gujrat conditions. Indian Sugar. 54 (8): 587-592. 21. Rathore, O. P., H. D. Verma and G. K. Nema. 1996. Effect of potassium application on growth, yield and quality of sugarcane. Indian Sugar. 46 (8): 665-668. Diunduh dari: ………. http://www.jar.com.pk/admin/upload/34__315Paper-No.5.pdf 84

Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. EFFECT OF K2O LEVELS AND ITS APPLICATION TIME ON GROWTH AND YIELD OF SUGARCANE Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. J. Agric. Res., 2010, 48(3). 315-325 Diunduh dari: ………. http://www.jar.com.pk/admin/upload/34__315Paper-No.5.pdf 85

Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. EFFECT OF K2O LEVELS AND ITS APPLICATION TIME ON GROWTH AND YIELD OF SUGARCANE Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. J. Agric. Res., 2010, 48(3). 315-325 Number of millable canes Effect of K2O levels and its application time on number of millable canes was significant over control treatment (T1) while all other treatments showed nonsignificant difference with each other during both years. Maximum number of millable canes (13.0/m2 during 2006 and 12.7/m2 during 2007) was recorded in T7 (84 kg K2O at sowing + 84 kg K2O/ha at 90 DAS) against minimum in T1 (10.1/m2 during 2006 and 9.7/m2 during 2007). These results agree to those of many workers (6, 7, 8, 9, 12, 21) while Hussain et al. (10), Ahmad et al. (2) and Singha (22) do not endorse the present findings who observed nonsignificant effect of K2O on number of millable canes. A positive and linear correlation between number of millable canes and stripped cane yield was observed during the year 2006 and 2007 which was further supported by regression model and showed dependence of stripped cane yield on number of millable canes. 2. Ahmad, M. S., G. Muhammad, M. Aslam and K. B. Malik. 1993. Effect of different levels and application times of potash fertilizer on the growth and yield of sugarcane. Pak. Sug. J. 7 (4): 3-6. 7. Bangar, K. S. and S. R. Sharma. 1995. Studies on the response of sugarcane to potassium and methods of application on medium block soils of Madhya Pradesh. Indian J. Sug. Tech. 10 (1): 6-9. 8. Bokhtiar, S. M., G. C. Paul, A. B. M. Mafizur Rahman and M. M. Alam. 2002. Response of NPK and S on the growth and yield of sugarcane grown in the calcareous dark grey floodplain soils of Bangladesh. Pak. Sug. J. 17 (1): 16-21. 9. Gawander, J. S., P. Gangaiya and R. J. Morrison. 2004. Potassium responses and budgets in the growth of sugarcane in Fiji. Sugar Int. 22 (1): 3-8. 12. Jeyaraman, S. and S. Alagudurai. 2003. Nitrogen and potassium management for yield maximization in sugarcane. Indian Sugar. 52 (12): 987-989. 21. Rathore, O. P., H. D. Verma and G. K. Nema. 1996. Effect of potassium application on growth, yield and quality of sugarcane. Indian Sugar. 46 (8): 665-668. 22. Singha, D. D. 2002. Nutrient requirement and time of application for sugarcane seed crop. Indian Sugar. 51 (12): 875-880. Diunduh dari: ………. http://www.jar.com.pk/admin/upload/34__315Paper-No.5.pdf 86

Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. EFFECT OF K2O LEVELS AND ITS APPLICATION TIME ON GROWTH AND YIELD OF SUGARCANE Abdul Ghaffar, M. Farrukh Saleem, Asghar Ali and Atta Muhammad Ranjha. J. Agric. Res., 2010, 48(3). 315-325 Sugar yield Sugar yield was also significantly affected by K2O levels and its application time during both years of experimentation. During 2006, maximum sugar yield (14.7 t/ha) was recorded in T7 (84 kg K2O at sowing + 84 kg K2O/ha at 90 DAS), which was statistically at par with all other treatments except control (T1) (7.7 t). During 2007, T10 (112 kg K2O/ha at sowing + 112 kg K2O/ha at 90 DAS) excelled in sugar yield (14.1 t/ha) against minimum (7.4 t/ha) in control treatment. Maximum sugar yield could be ascribed to higher stripped cane yield and CCS percent. Rathore et al. (21), Akhtar et al. (3) and Gawander et al. (9) also recorded higher sugar yield with increased rate of K2O. 3. Akhtar, M., C. S. Rafiq, M. E. Akhtar, M. Z. Khan and B. Khurram. 2000. Effect of varying phosphorus and potash levels on agronomic traits and productivity of sugarcane. Pak. J. Biol. Sci. 3 (5): 852-853. 9. Gawander, J. S., P. Gangaiya and R. J. Morrison. 2004. Potassium responses and budgets in the growth of sugarcane in Fiji. Sugar Int. 22 (1): 3-8. 21. Rathore, O. P., H. D. Verma and G. K. Nema. 1996. Effect of potassium application on growth, yield and quality of sugarcane. Indian Sugar. 46 (8): 665-668. Diunduh dari: ………. http://www.jar.com.pk/admin/upload/34__315Paper-No.5.pdf 87

PENTINGNYA KALIUM BAGI PERTANAMAN TEBU …. Wassalam….. Foto: smno.kampus.ub.nop2012 88