Effects of Potassium Fertilization on Growth and Yield of Wetland Rice in Grey Terrace Soils of Bangladesh AMINUL ISLAM 1* , JATISH CHANDRABISWAS 1 , A. J. M. SIRAJUL KARIM 2 , MST. SALMAPERVIN 3 , AND MD. ABU SALEQUE 4 1*-Soil Science Division, Bangladesh Rice Research Institute, Gazipur-1701, Bangladesh 2-Department of Soil Science, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Salna, Gazipur- 1706, Bangladesh 3-Plant Physiology Division, Bangladesh Rice Research Institute, Gazipur-1701, Bangladesh 4-CASR, Bangladesh Rice Research Institute, Gazipur-1701, Bangladesh *Corresponding author Email: aminbrri@gmail.com Received:20 June 2015 Accepted: 2 July 2015 ABSTRACT Variable rates (0, 20, 40, 60 and 80 kg ha -1 ) of potassium (K) fertilization effects on growth, yield as well as the relationship between yield and growth parameters of T. Aman (monsoon season) rice were examined in 2010 at Bangladesh Rice Research Institute (BRRI) research farm, Gazipur, Bangladesh following randomized complete block design with three replications. Test rice variety was BRRI dhan49 and the soil was Aeric Haplaquept. Plant height, panicle length, dry matter production at maturity, straw and grain yields significantly (p < 0.01) increased in a quadratic fashion; but tillersm -2 , panicles m -2 , spikelet panicle -1 , filled grains in a panicle, dry matter yield at panicle initiation (PI) stage increased significantly (p < 0.01) in a linear fashion when K rates were increased from 0 to 80 kg ha -1 . Maximum grain yield (4958 kg ha -1 ) was obtained at 80 kg K ha -1 . Panicles m -2 , spikelets in a panicle, filled grains, dry matter yield, harvest index, 1000 grain weight had significant positive association with grain yield. Optimum K rate and K requirement of BRRI dhan49 was found to be 64.14 kg ha -1 13 kg t -1 rice. Calculated K dose for T. Aman rice was much higher than the recommended dose. Therefore, potassium dose for wet season rice should be increased for desired yield otherwise potassium mining from soil and yield reduction might be occurred. Keywords: Yield component, Dry matter, Harvest index, Association INTRODUCTION In Bangladesh, rice is grown in Aus (pre-monsoon, April to June), Aman (Monsoon, July to November) and Boro (dry season irrigated, December to June) seasons. Five fertilizers are generally use for cultivation of rice (Shah et al., 2008) of which K is required for plant growth and fecundity (Rengel and Damon, 2008; Fageria et al., 2011). Lack of K restricts the establishment, development, and yield of crops (Rengel and Damon, 2008). Potassium is required for the activity of many enzymes, including those of energy metabolism, protein synthesis, and solute transport. Also it contributes significantly to cell turgor, especially in ORIGINAL RESEARCH Research on Crop Ecophysiology Vol. 10/2, Issue 2 (2015), Pages: 64 - 82