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%.
