PENTINGNYA HARA K DAN PUPUK BAGI TANAMAN TEBU Bahan kajian MK Pupuk dan Pemupukan Diabstraksikan oleh Prof Dr Ir Soemarno MS Jur Tanah FP UB Oktober 2011 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

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 3

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. 4

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. 5

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. 6

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%. 7

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. 8

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 9

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. 10

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. 11

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 12

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. 13

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. 14

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. 15

The potassium cycle in the soil-plant-animal system (from SYERS, 1998) 16

Effect of K on sucrose content and sugar yield of cane in India (IPI on-farm trials, 2001) 17

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. 18

MEKANISME PENYERAPAN K+ OLEH AKAR   Proses pertukaran kation antara akar tanaman dengan aprtikel tanah http://click4biology.info/c4b/9/plant9.2.htm 19

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. http://click4biology.info/c4b/9/plant9.2.htm 20

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. http://click4biology.info/c4b/9/plant9.2.htm 21

. Fotoreduksi (reduksi FeIII cyanide) dan foto-fosforilasi dalam kloroplast merupakan fungsi dari konsnetrasi K+ (K1 = suplai K suboptimum, K2 = suplai K optimum) 22

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). 23

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 24

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 25

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 26

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.. 27

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 28

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. 29

Potassium nutrient management for planting area of the sugarcane TOTAL KALIUM DALAM TANAH •The soil of the total potassium was≤5 g/kg and accounts for 88.5%, •the total potassium was between 5 to 10 g/kg and accounts for 9.6%, •the content of the total potassium was between 10 to 15 g/kg and accounts for 1.9%, •there is no soil that content of the total potassium is greater than 15 g/kg. Potassium nutrient management for planting area of the sugarcane Hongwei Tan Liuqiang Zhou Rulin Xie Meifu Huang (soil and fertilizer institute, Academy of Agricultural Sciences of Guangxi, 530007) 30

Potassium nutrient management for planting area of the sugarcane KALIUM LAMBAT TERSEDIA DALAM TANAH The slow release available potassium was ≤30 mg/kg and accounts for 25%, the slow release available potassium was between 30 to 60 mg/kg and accounts for 50%, the slow release available potassium was between 60 to 120 mg/kg and accounts for 17.3%, the slow release available potassium was between 120 to 180 mg/kg and accounts for 5.8%, the slow release available potassium was between 180 to 240 mg/kg and accounts for 1.9%, there is no soil that slow release available potassium of soil is greater than 240 mg/kg. Potassium nutrient management for planting area of the sugarcane Hongwei Tan Liuqiang Zhou Rulin Xie Meifu Huang (soil and fertilizer institute, Academy of Agricultural Sciences of Guangxi, 530007) 31

Potassium nutrient management for planting area of the sugarcane Klasifikasi kalium tersedia dalam tanah untuk produksi tebu Potassium nutrient management for planting area of the sugarcane Hongwei Tan Liuqiang Zhou Rulin Xie Meifu Huang (soil and fertilizer institute, Academy of Agricultural Sciences of Guangxi, 530007) 32

Potassium nutrient management for planting area of the sugarcane JUMLAH KALIUM YANG DISERAP TANAMAN TEBU Setiap satu hektar tanaman tebu menyerap K2O sebanyak 100.91 - 315.28 kg. The result of the field experiments is indicated, the sugarcane yield with potassium absorbed amount of sugarcane present positive correlation, coefficient correlation r=0.979**, Whether reach remarkable level extremely, sugarcane yield (y) relational expression with function of sugarcane who absorbed potassium (x):y=31687.1+ 246.0x. Potassium nutrient management for planting area of the sugarcane Hongwei Tan Liuqiang Zhou Rulin Xie Meifu Huang (soil and fertilizer institute, Academy of Agricultural Sciences of Guangxi, 530007) 33

Potassium nutrient management for planting area of the sugarcane Change of potassium absorbing intensity for sugarcane in different period ofduration Potassium nutrient management for planting area of the sugarcane Hongwei Tan Liuqiang Zhou Rulin Xie Meifu Huang (soil and fertilizer institute, Academy of Agricultural Sciences of Guangxi, 530007) 34

Potassium nutrient management for planting area of the sugarcane Change of N, P and K nutrient content for sugarcane in different growth stage （CK） Potassium nutrient management for planting area of the sugarcane Hongwei Tan Liuqiang Zhou Rulin Xie Meifu Huang (soil and fertilizer institute, Academy of Agricultural Sciences of Guangxi, 530007) 35

Sugar Industry Research Institute, Réduit, Mauritius KALIUM BAGI TEBU 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 36

RESPON TEBU TERHADAP KALIUM 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 Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 37

RESPON TEBU TERHADAP KALIUM 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 38

TANAMAN TEBU MEMERLUKAN BANYAK KALIUM 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, R.A. 1990. The roles of nitrogen, phosphorus and potassium in the production of sugarcane in South Africa. Fertilizer Research 26: 87-98. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 39

MEMERLUKAN BANYAK KALIUM TANAMAN TEBU MEMERLUKAN BANYAK KALIUM 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, 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 40

MEMERLUKAN BANYAK KALIUM TANAMAN TEBU MEMERLUKAN BANYAK KALIUM 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, 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 41

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 The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 42

Sugar Industry Research Institute, Réduit, Mauritius Effect of K manuring on height, stalk population and yields of sugarcane (Donaldson et al., 1980) 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 43

KALIUM DAN RENDEMEN TEBU 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, 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 44

DEFISIENSI KALIUM TANAMAN TEBU 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 45

DEFISIENSI k DAN FOTOSINTESIS TEBU 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 46

Sugar Industry Research Institute, Réduit, Mauritius RESPON PUPUK KALIUM 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. Prasad et al. (1996), 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. 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. The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 47

high available K as extracted in 0.1M H2SO4 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 The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 48

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 The Effects of Potassium on Growth, Development, Yield and Quality of Sugarcane K.F. NG KEE KWONG Sugar Industry Research Institute, Réduit, Mauritius 49

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. 50

KALIUM & PRODUKSI TEBU In Andhra Pradesh optimum level of harvesting time was observed 12.96 months after planting at optimum level of 119.7 kg/ha. of K2O and yield was 1106.87 q/ha. In Bihar, optimum level of harvesting time was observed 11.04 months after planting at optimum level of 175.89 kg/ha. of K2O and yield was 1407.90 q/ha. In Karnataka, optimum level of harvesting time was observed 16 months after planting at optimum level of 151.9 Kg/ha. of K2O and yield was 1666.83 q/ha. In Uttar Pradesh, optimum level of harvesting time was observed 14 months after planting at optimum level of 177.5 Kg/ha. of K2O and yield was 692.45 q/ha. In most of the states early harvesting and late harvesting of sugarcane were not beneficial for maximum yield. Kumar Rajendra, Sharma S.C., Singh N.P. 2007.Effect of optimum time of harvesting and dose of potash for sugarcane crop. Bhartiya Krishi Anusandhan Patrika. 2007, Vol. 22, No.4, p. 257- 262 . 51

Phosphate and potash requirements of sugar cane in relation to soil chemical analysis and soil type. ICR Holford Australian Journal of Experimental Agriculture and Animal Husbandry 6(23) 409 - 417 Percentage yields of sugar cane in fertilizer field experiments harvested over a five-year period were highly correlated with soil test levels in the control plots. The regressions of percentage yield on soil test level were curvilinear, and a modified Mitscherlich equation gave an excellent fit to the points. Critical soil test levels were found to exist, below which soils gave significant yield responses to applied nutrients. Critical soil test levels ranged over 5 to 20 p.p.m, for phosphorus and 51 to 150 p.p.m. for potassium. Within the deficient range of each nutrient there were only weak relationships between optimum fertilizer requirements and soil test levels. There was some evidence to suggest that soil type may be a useful complementary criterion for predicting fertilizer requirements. 52

M.S. KHADR, A.Y. NEGM, F.A. KHALIL, L.W. ANTOUN Effect of Potassium Chloride in Comparison with Potassium Sulfate on Sugar Cane Production and some Soil Chemical Properties under Egyptian Conditions M.S. KHADR, A.Y. NEGM, F.A. KHALIL, L.W. ANTOUN Soil, Water and Environment Res. Inst., Agric. Res. Center, Giza, Egypt. Two field trials were carried out at two private locations (El-Sheikh Makram and Shandaweel El- Balad) in Sohag Governorate (Upper Egypt, loamy soil) to investigate the effect of potassium fertilizer rate (115 and 230 Kg K2O / ha) and source, i.e. potassium sulfate (SOP) and potassium chloride (MOP). The obtained results showed slight changes in melable and sugar yields of the first two cuts, at El-Sheikh Makram, due to K fertilizer application in favor of SOP with no specific trend, while melable and sugar yields of the second ratoon showed marked increases when recommended K rate was doubled in both K forms in favor of SOP also. At the second location of Shandaweel El-Balad, although some adverse effects on melable and sugar yields of plant cane were noticed due to MOP application with minor effects for SOP, the higher K rate as SOP and the recommended one as MOP induced increases in melable and sugar yields of the first ratoon but these increases did not reach the significance. On the other hand, no salinity building up or Cl accumulation due to MOP application was detected at the soil of the two locations, while K application at both rates of the two sources resulted in different increases in the available soil K with no marked differences between the two K sources. 53

Effect of phosphorus and potassium fertilization on sugar cane production in Upper Egypt. Abd El-Hadi, A.H.; M.A. El-Akabawy; A.Y.Negm and M.M.Seleem (1992). Proc. 5th Conf. Agron. Zagazig, 13-15 Sept. The melable cane yield was increased by 11.17% and sugar yield by about 12.18% due to the addition of 48 Kg K2O/ fed. They added that from the economical point of view, the addition of 48 Kg K2O/ fed was more superior for higher sugar cane yield production and sugar yield than the rate of 96 Kg K2O/ fed. 54

Bragantia . 1962, vol.21, n.unico, pp. 31-43. FERTILIZER EXPERIMENTS WITH SUGAR CANE VI - SPLIT-APPLICATIONS OF POTASH. ALVAREZ, R.  and  FREIRE, E. S.. Bragantia . 1962, vol.21, n.unico, pp. 31-43. Rates of applications of 90, 180 and 270 kilograms of K2O to the hectare were compared in the presence of NP, each rate being applied in three ways: according to the usual method, i. e. the whole quantity in the furrows, at planting time; half the quantily at planting and half two months later; one third ot planting and each of the other two thirds two ond 8 1/2 months afterwards. In São Paulo the cane cuttings are planted in deep furrows and slightly covered with soil, the filling of the furrows being achieved gradually, with the usual cultivations. The first post-planting application was made in those semi-filled furrows; the second, 20 centimeters to the side of the rows, as the furrows were almost levelled. The average response to potash was very high, but the methods of application did not differ significantly. Nevertheless, it was observed that the higher rotes were more effective when sptitted, and the advantoge of splitting increased as the total dose was increased. It seems that no appreciable losses by leaching of the doses applied at planting ocurred. On the other hand, the plants could utilize the post-planting fractions, for they were present in soil layers where roots developped before the period of intensive uptake of nutrients. Besides reducing possible losses by leaching in certain soils, sppliting of higher rates of potash would contribute to ovoid excessive salt concentration in the planting furrows. Although some symptoms of salt-injury were observed, the damage was not serious in the present experiment, because it rained before and soon after planting. 55

Aman Ullah Chudhry and Amir Ahmad Determination of Optimum Level of Potash and its Effect Son Yield and Quality of Sugarcane Aman Ullah Chudhry and Amir Ahmad   Pakistan Journal of Biological Sciences Year: 2000. Vol. 3 Issue. 7 Page1152-1153 The results showed that the potash levels did not influence significantly the yield and yield components like the number of mailable cane at harvest m-2, cane length (m), cane diameter, number of internodes per cane, internodal length and weight per stripped cane. Similarly quality parameters like sucrose contents and commercial cane sugar showed non significant response to potassium. The highest stripped cane yield of 1000.83 t ha-1 was obtained with 180 kg K2O ha-1. 56

Study of the optimum time of harvesting and dose of potash for maximum Sugarcane yield by using Response Surface Methodology Kumar, Rajendra; Sharma, S C, Singh, N P. Page(s): 172-176 ISSN: 0771-7706 BVAAP Vol.15(2) [December 2007] The combined results of the experiment after pooling over number of years/locations will be more broad based and more stable and help research workers in formulating their future experimental programmers and the extension workers in disseminating information for practical farming. The object of this study was to find the optimum time of harvesting and dose of potash for sugarcane crop in various states of the country by using suitable response surface model. In most of the cases optimum times of harvesting and doses of potash were calculated by using Quadratic Response Surface model for sugarcane crop. In Andhra Pradesh optimum level of harvesting time was observed 12.96 months after planting at optimum level of 119.7 kg/ha of K₂O and its yield was 1106.87 qlha. In Bihar, optimum level of harvesting time was observed 11.04 months after planting at optimum level of 135.9 kg/ha of K₂O and yield was 796.00 qlha. In Maharashtra, optimum level of harvesting time was observed 13.49 months after planting at optimum level of 175.89 kg/ ha of K₂O and yield was 1407.90 q/ha. In Kamataka, optimum level of harvesting time was observed 16 months after planting at optimum level of 151.9 kg/ha of K₂O and yield was 1666.83 q/ha. In Uttar Pradesh, optimum level of harvesting time was observed 14 months after planting at optimum level of 177.5 kg/ha of K₂O and yield was 692.45 q/ha. In most of the states early harvesting and late harvesting of sugarcane were not beneficial for maximum yield. 57

Effect of Various Levels of Potash Application Through Drip Irrigation on Yield and Quality of Sugarcane Deshmukh, A.S., P.P. Shinde, S.S. Katake, D.B. Phonde, V.S. Mali, and P. Imas. e-ifc No. 24 September 2010 Cane yield significantly changed in response to the irrigation method and fertigation. A significant increase in yield and commercial cane sugar (CCS) was achieved by using drip system (T2) instead of flood (T1), despite a large decrease in water used. 58