Effects of Potassium Fertilization on Growth and Yield of Wetland Rice in Grey Terrace Soils of Bangladesh

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.