Characterization of physiological, biochemical, and agronomical traits of elite induced chickpea mutants from the northwestern Himalayan region of the UT of J & K, India

Abstract

Chickpea is one of the key grain legume crops in the world. India is the largest producer, consumer, and importer of chickpea. This study aimed to induce chickpea mutants through gamma rays for cold tolerance and identify the most promising cold-tolerant chickpea mutants. A total of 257 induced mutants were developed and screened under in vitro and in vivo conditions in the present study, including three checks: one control (GNG1958), one national susceptible (ICC12968) check, and one national cold-tolerant check (ICC92944). The study was conducted during the R abi season of 2023–24 and 2024-25. Electrolyte leakage index in percent (ELI%), total chlorophyll content (TCC), and carotenoid content (CC) were tested under in vitro conditions, and cold tolerance rating (CTR) scale, frost resistance ratio (FRR), and seed yield (g plant -1 ) were tested under in vivo conditions. Analysis of pooled mean data of mutants of both years led to the identification of 50 promising induced mutants for cold tolerance. Of these 50, 26 induced mutants exhibited less than 10% electrolyte leakage index (ELI %) with more than 0.50 mg g -1 FW carotenoid content, indicating resistance against cold stress at the vegetative stage during high cold stress. Of these 26, three highly promising cold-tolerant mutants were identified: 335.74 Gy-Ch-M-45 (electrolyte leakage index 6.79%, total chlorophyll content 2.48 mg g -1 FW, carotenoid content 0.85 mg g -1 FW, cold tolerance rating scale 1.5, frost resistant ratio 0.80, and seed yield 48.78 g plant -1 ), 335.74 Gy-Ch-M-155 (electrolyte leakage index 7.24%, total chlorophyll content 2.26 mg g -1 FW, carotenoid content 0.82 mg g -1 FW, cold tolerance rating scale 2.0, frost resistant ratio 0.94, and seed yield 59.22 g plant -1 ), and 335.74 Gy-Ch-M-66 (electrolyte leakage index 7.30%, total chlorophyll content 2.49 mg g -1 FW, carotenoid content 0.84 mg g -1 FW, cold tolerance rating scale 2.00, frost resistant ratio 0.88, and seed yield 36.40 g plant -1) . Seed yield (g plant -1 ) exhibited a significant positive correlation with total chlorophyll content, carotenoid content, and frost-resistant ratio but showed a significant negative correlation with electrolyte leakage index and cold tolerant rating scale. A significantly positive correlation was found between electrolyte leakage index (ELI%) and cold tolerance rating (CTR) scale (r = 0.87, p  < 0.01), implying greater leakage of electrolytes in mutants with increased cold tolerance rating. The maximum variation for seed yield (g plant -1 ) may indicate stable gene mutations in subsequent generations. Non-additive gene action was observed for all cold tolerance traits in M 2 and M 3 generations, which indicates epistasis, dominance, and genotypic and environmental interaction; hence, their response to selection would be poor. Mutants, viz. , 254.90 Gy-Ch-M-01 and 254.90 Gy-Ch-M-32, showed higher sugar content, proline content, and protein percentage, and desired values of cold tolerance traits, viz. , electrolyte leakage index (ELI %), cold tolerance rating (CTR) scale, and frost resistance ratio (FRR), compared to control (GNG1958), along with higher seed yield. These elite mutants (254.90 Gy-Ch-M-01 and 254.90 Gy-Ch-M-32) showed desired values for eight and nine traits of cold tolerance parameters, respectively, along with seed yield (g plant -1 ). The promising candidate cold-tolerant mutants with higher seed yield (g plant -1 ) identified during the present study could be used in chickpea breeding programs aimed at improving cold tolerance of cultivated chickpea worldwide.