Nitrogen Use Efficiency of Transplanted Rice as Influenced by N, P and K Levels

摘要

The effect of three levels each of N (150, 200 and 250 kg ha~(~(-1))), P (33, 44 and 55-kg ha~(-1)) and K (62, 83 104 kg ha~(~(-1))) on grain yield and N-use efficiency in irrigated rice was studied at Agricultural Research Station, Gangavathi, Karnataka during kharif 2000 and summer 2001. Application of 250 kg N ha~(-1) recorded higher N uptake (150 and 151 kg ha~(-1) during kharifand summer 2001, respectively) than recommended 150 kg N ha~(-1) (122.8 and 112.8 kg N uptake ha~(-1), respectively during kharifand summer). Agronomic-N-use efficiency decreased at 250 kg N ha~(-1) (17.5 kg grain kg~(-1) N ) as compared to 150 kg N ha~(-1) (21.6 kg grain kg~(-1) N) in the summer, while in kharifit was higher at 200 kg N ha~(-1) than 150 kg N ha~(-1) butdecreased with further increase in N rate. Application of P up to 55 kg ha~(-1) in kharif and up to 44 kg ha~(-1) in summer recorded higher N-recovery (36.2 and 40.9% in kharifand summer, respectively) and agronomic efficiency (11.0 and 20.1kg grain kg~(-1), N respectively during kharifand summer). Potassium at different levels ranging from 62 to 104 kg ha~(-1) had no significant effect on N-use efficiency. Application of 200:44:62 and 250:44:62 kg N, P and K ha~(-1) in kharifand summer resulted in higher grain yields than recommended practice mainly by improving N uptake.