Introduction

Chickpea (Cicer arietinum L.) is an important food legume in dryland farming systems and is widely cultivated in regions where water availability is limited. In many areas of Iran, chickpea is traditionally grown in spring; however, autumn sowing can provide advantages such as better utilization of winter precipitation, earlier crop establishment, and potentially improved yield under dryland conditions. The major limitation to the expansion of autumn-sown chickpea in cold and high-altitude regions is the occurrence of low temperatures during early vegetative growth. Therefore, the identification and utilization of cold-tolerant genotypes are important prerequisites for developing cultivars suitable for autumn cultivation in cold dryland environments. The objective of this study was to evaluate the phenotypic variation for cold tolerance among Iranian Kabuli chickpea landraces, estimate genetic parameters for important traits, and identify promising genotypes for use in chickpea breeding programs.

Materials and Methods

In this study, 79 Kabuli-type chickpea landraces from six provinces of western and northwestern Iran, including East Azerbaijan, West Azerbaijan, Ardabil, Kurdistan, Kermanshah, and Lorestan, were evaluated along with the cold-tolerant check ‘Ana’ and cold-sensitive check ‘ILC533’, comprising 81 genotypes in total. Cold tolerance was assessed under both controlled and field conditions. Ten seeds of each genotype were grown in each pot until the three-leaf stage. Plants were initially maintained at 20 °C, and the temperature was then gradually reduced by 2 °C every 3 h until reaching -16 °C. Plants were maintained at -16 °C for 2 h, followed by exposure to 4 °C for 24 h and subsequent recovery under greenhouse conditions. The number of surviving plants before and after cold stress (PC1 and PC2, respectively) was recorded, and survival percentage (SU) was calculated as SU =(PC2/PC1) × 100. Cold tolerance (CT) was evaluated using a 1–9 scoring scale, with lower scores indicating greater tolerance. Electrolyte leakage index (ELI) was measured as an indicator of membrane damage. Field evaluation was conducted under dryland conditions during the 2024–2025 growing season. Plant height, days to flowering, days to maturity, 100-seed weight, and grain yield were recorded. Data were analyzed using analysis of variance, genotypic and phenotypic coefficients of variation (GCV and PCV), broad-sense heritability, genetic advance, and genetic advance as a percentage of the mean. Correlation, principal component analysis (PCA), and cluster analyses were also performed. Cluster analysis was based on squared Euclidean distance and Ward’s method.

Results and Discussion

The results demonstrated substantial phenotypic variation among the evaluated chickpea genotypes for cold-tolerance-related and agronomic traits. The overall means for survival percentage, electrolyte leakage index, cold tolerance score, plant height, days to flowering, days to maturity, 100-seed weight, and grain yield were 89.76%, 81.43%, 3.97, 43.40 cm, 159 days, 199 days, 33.79 g, and 712.6 kg ha⁻¹, respectively. The considerable variation observed among genotypes indicates the presence of useful phenotypic diversity that can be exploited in breeding and selection programs. The highest GCV and PCV values were observed for cold tolerance, with values of 76.83% and 74.91%, respectively, followed by electrolyte leakage index, with GCV and PCV values of 26.70% and 27.18%, respectively. In contrast, days to flowering and days to maturity showed relatively lower variation. Broad-sense heritability was relatively high for the evaluated traits, ranging from 44.87% for days to flowering to 96.45% for electrolyte leakage index. The highest genetic advance as a percentage of the mean was obtained for cold tolerance (146%), followed by electrolyte leakage index (53.13%), suggesting considerable scope for effective selection based on these traits. Under controlled cold-stress conditions, 10 genotypes were classified as susceptible, 9 as moderately tolerant, and 62 as tolerant. Field evaluation also demonstrated considerable differences among genotypes in their response to cold conditions, with 6 genotypes classified as susceptible, 39 as moderately tolerant, and 36 as tolerant. Correlation analysis showed strong relationships among the principal cold-tolerance traits. Cold-tolerance score was positively and strongly correlated with electrolyte leakage, whereas both traits were negatively correlated with survival percentage. These relationships indicate that genotypes showing greater membrane injury generally had lower survival under cold stress. Cold-tolerance score and electrolyte leakage were also negatively associated with grain yield, while survival percentage showed a positive association with yield. Therefore, survival percentage and electrolyte leakage can provide complementary criteria for screening, while grain yield can be used to verify the agronomic value of selected materials. Principal component analysis based on cold-tolerance and agronomic traits indicated that the first two principal components accounted for approximately 67% of the total phenotypic variation, with about 44% explained by PC1 and 23% by PC2. Electrolyte leakage, survival percentage, cold-tolerance score, grain yield, 100-seed weight, and plant height contributed to the differentiation of genotypes in the PCA space. The distribution of genotypes demonstrated both differentiation and overlap among the evaluated landraces, reflecting the multidimensional nature of cold response. Cluster analysis based on Ward’s method further separated the genotypes according to their overall phenotypic similarity. In particular, genotypes G78 and G79 were positioned close to the cold-tolerant check ‘Ana’, indicating that these materials may warrant further evaluation as potential sources of cold-tolerance-related variation.

Conclusions

The findings demonstrated considerable phenotypic variation for cold tolerance and agronomic performance among Kabuli chickpea landraces from western and northwestern Iran. The high heritability estimates and relatively high genetic advance observed for several traits, particularly survival percentage and electrolyte leakage, indicate that these traits can be useful for selection. The strong relationships among survival percentage, electrolyte leakage, cold-tolerance score, and grain yield further support the use of multiple complementary traits for identifying superior genotypes. The tolerant landraces identified in this study represent valuable genetic resources for chickpea improvement and may contribute to the development of cultivars adapted to autumn sowing in cold dryland environments.