N fixation potential of cowpea and mungbean lines and its effects on succeeding maize crop

Abstract

Nitrogen fixation potential of selected cowpea and mungbean cvs. and its effect on succeeding maize crop was studied at the seed farm of the Department of Agriculture, Bata-atha, in the low country dry zone of Sri Lanka. At first stage, six lines of cowpea were used with maize and sorghum as controls. The amount of N fixed was measured using 15N methodology. At second stage, effect of N2 fixation on growth, yield and N yield of succeeding maize crop was determined. High genotypic variability in %Ndfa was observed and cowpea lines derived 49-76% of their N requirement through BNF, while mungbean lines derived 45-70% from BNF. Further, all cowpea lines contributed positively towards N yield of the succeeding maize crop compared to controls and it was in the range of 16-48%. Cowpea lines IT 86D-1054, IT 81-D 994 and Bombay resulted in higher residual effects giving 48%, 44% and 20% increase in N yield, of the succeeding maize crop, respectively. But the residual effect of preceding mungbean lines was not promising except in VC 3580, which was increased by 26%.