Evaluation of Biological Nitrogen Fixation and Water Use Efficiency of Chickpea Genotypes in Response to Biochar Application

Abstract

Biochar has been widely recognised as a soil amendment capable of improving soil fertility, biological nitrogen fixation, and water-use efficiency in leguminous crops. This study evaluated the effects of three biochar rates (0, 15, 30 t/ha) on biological nitrogen fixation, yield components, and water use efficiency of four chickpea genotypes under pot conditions. The experiment was arranged in a factorial Completely Randomised Design with three replications. A pot experiment was conducted at the University of Venda’s School of Agriculture Experimental Farm situated in Thohoyandou, Limpopo province. The experiment used a 4×3 factorial design with poultry biochar type (PL), three biochar rates (0, 15, and 30 t/ha), and four desi chickpea genotypes (Striker, Slasher, Monarch, Moti, and Pistol). Pots measuring 25 cm in height and 25 cm in diameter were filled with 5 kg of loamy sand soil of Glenrosa. Roots and shoots were sampled at the podding stage and dried at 105 C to o tain consistent dry weight. Grain yield collected at harvest maturity was air-dried and weighed. The data obtained were subjected to ANOVA in GenStat, and significant means were compared using the LSD test (P≤0.05). Results showed that iochar application significantly (p≤0.05) enhanced nodule num er, nodule dry weight, pods per plant, seed per pod, and grain yield compared to the control. Higher biochar rates improved biological nitrogen fixation, as evidenced by increased nodulation and plant vigour. Significant differences were also observed among genotypes, indicating genetic variability in response to biochar amendment. The interaction between biochar rates and genotypes was significant for most measured parameters, suggesting that genotypes differed in their efficiency to utilise improved soil conditions. Water use efficiency increased with increasing biochar rate, likely due to improved soil moisture retention and enhanced nutrient availability. Among the tested genotypes, the highest grain yield and water-use efficiency were observed at the highest biochar rate, demonstrating the synergistic effect of the soil amendment and genetic potential. The study concluded that biochar application, particularly at higher rates, can improve biological nitrogen fixation and water use efficiency in chickpea. Selection of responsive genotypes combined with appropriate biochar management may therefore enhance suitable chickpea production under limited water conditions.