Evaluation and identification of chickpea gamma-ray mutant lines for their high yield, nitrogen, and water use...

This study aimed to identify chickpea M₃ mutant lines with high yield potential and improved resource-use efficiency under contrasting water regimes using isotopic analysis.

A split-plot factorial design was used to evaluate 17 chickpea M₃ mutant lines under irrigated and rainfed conditions. The measured traits included phenology (flowering and maturity), plant height, hundred-seed weight, seed yield, seed nitrogen content, and drought-related parameters such as nitrogen fixation, carbon isotope discrimination (Δ¹³C), chlorophyll content, relative water content, and canopy temperature.

Genotype significantly affected all measured traits, whereas the water regime influenced all traits except for the hundred-seed weight and seed nitrogen content. The genotype × water-regime interaction affected maturity and Δ¹³C. Seed yield was positively correlated with maturity, plant height, Δ¹³C, seed nitrogen content, chlorophyll content, and relative water content, and negatively correlated with canopy temperature, thereby confirming the relevance of Δ¹³C as a drought-tolerance indicator. Principal Component Analysis explained 63.12% of the variation under irrigation and 59.93% under rainfed conditions, mainly driven by hundred-seed weight, plant height, yield, seed nitrogen content, and flowering time. Cluster analysis grouped the 18 genotypes into four subclusters under both the rain-fed and irrigated regimes.

Sixteen out of the 17 M₃ mutant lines outperformed the parent variety under irrigation, and six under rainfed conditions. Lines G4 and G17 showed the highest yields in both environments. Sixteen lines displayed lower Δ¹³C values than the parent under rainfed conditions, indicating greater drought resilience. Lines G10 and G3, with the lowest Δ¹³C, despite lower yields.