Combined Effect of NPK on Grain Yield of Broadcast Aus Rice in the Coastal Soil of Southwestern Bangladesh

Abstract

The yield potentiality of rice mostly depends on the judicious management and appropriate combination of applied nutrient. In southwestern region of Bangladesh broadcasting (B) Aus rice has been emerging as a new cultivation technique instead of Transplanting (T) but the nutrient measurement of this rice was not determined. Therefore, the field experiment was carried out with ten combinations of nitrogen (N), phosphorus (P) and potassium (K). The N, P and K rates were taken from the transplanted (T) Aus rice @ 70-10-55 kg ha-1 as 100% of each N, P and K, respectively, and those doses were varied as per cent of full rates as 100%, 75%, 50% and 25%. There was treatment with no added N, P and K. The treatments were (N-P-K kg ha-1) 0-0-0, 0-100- 100, 100-0-0, 100-25-100,100-100-100, 100-100-25, 100-100-75, 100-50-100, 100-100-50 and 100-75-100 per cent of recommended N, P, K to evaluate the effect NPK combination of growth, yield attributes and yield of Aus rice (BRRI dhan48). The NPK combination of @100-100-100 kg ha-1 significantly produced (p<0.01) the highest plant height, tiller number, panicle length, number of filled grain panicle, 1000 grain weight, grain yield, straw yield, biological yield, SPAD value, effective tiller except unfilled grains (@ (100-0-0 kg ha-1) and lowest was produced from no NPK added plot. The results revealed that N highly significantly affected the growth, yield attributes and yield of rice while P and K had minor effect on the measured parameters. N was found the main yield determinant. Yield reduction was observed very low due to the omission of P and K., respectively, with the similar rate of N. When N omitted the yield decreased drastically (~41%) but omission of P and K had little influence on yield. This might be due to the low soil N content and moderate to high P and K content in the soils of this region. The highest grain yield was obtained with an NPK combination of @100%-100%-100% of recommended rate which increased grain yield by 9.23-83.58% over other treatments. From the findings of this study, we concluded that NPK @ 100-100-100 kg ha-1 is the suitable combination for the broadcasting cultivation of BRRI dhan48 in the coastal soils of southwestern Bangladesh.