Effect of Varieties and Levels of N,P and K on Growth,Yield and otassium Balance in Rice-Wheat Cropping System

摘要

A field experiment was conducted with three levels of N,P and K with three rice varieties in Kharif and three eat varieties in Rabi with similar N,P and K levels in rice-wheat sequence during the year 1993-94 and 1994-95 at Pusa,Bihar.The maximum rice equivalent yield of 133.71 q ha~(-1)was recorded at the highest fertilizer level (N:P_2O_5:K_2O::120:60:60 kg ha~(-1))which was significantly higher.Among varieties,Kanak of rice and RW-346 of wheat produced the highest rice equilvanet yield (122.15 q ha~(-1))during first year and by Rajshree of rice and Sonali of wheat (115.36 q ha~(-1))during second year and both sequences were at par but significantly higher than the third sequence,Radha of rice and UP-262 of wheat during both the experiental years.Leaf area index was found to increase up to 75 days after transplanting/sowing and maximm values were recorded in rice (7.30 and 6.79 in 1993 and 1994,respectively)and wheat (3.71 and 3.76 in 1993-94 and 1994-95 respectively)with the application of 120 kg N,60 kg P_2O_5 and 40 kg K_2O per hectare.Among varieties,Radha and Rajshree of rice and RW-346 and Sonali of wheat had the higher leaf area index (LAI)vaues.Dry matter production increased significantly with every increaed levels of fertilizer.Among varieties,Radha and Rajshree rice and RW-346 and Sonali of wheat recorded highe dry matter production than Kank of rice and UP-262 of wheat.Maximum K_2O uptake was recorded at hgiehst leel of potassium application (40 kg K_2O ha~(-1)).Potassium balance after harvest of fourth crop was increased with increase in potassium application with hgihest balance at 40 kg K_2O ha~(-1) (+254.97 kg/h).Among varieties,highest balance of +210.36 kg ha~(-1) was recorded by Rajshree of rice and Sonali of wheat.