Comparison of direct and indirect methods of measuring nitrogen fixation in field grown chickpea genotypes

Abstract

Field experiments were conducted to study the nitrogen fixing potential of cultivars and breeding lines of chickpea (Cicer arietinum) where 20 chickpea genotypes were compared using the 15N isotope dilution technique, acetylene reduction assay (ARA) and yield parameters such as biomass, grain and total nitrogen. Great differences in nitrogen fixation were observed between and within the experiments. Proportion of nitrogen fixed from air (Pfix) and nitrogen derived from air (Ndfa) ranged from 23-68% and 4-61 kg ha-1 for the first year and 37-62% and 24-60 kg ha-1 for the second year, respectively. There was highly significant correlation between yield and N2-fixation but these were non-significantly correlated with nodulation data and ARA. The nodulation and ARA data were not good for field evaluation of chickpea cultivars suggesting that simple yield parameters like grain and total nitrogen yield could be used to screen a large germplasm in field as compared to highly expensive and laborious 15N dilution technique.