Preliminary selection of desi chickpea genotypes to introduce cold tolerant cultivars for autumn planting in cold regions

In temperate climates, cool-season plants are usually grown in autumn. Due to the proper establishment of the plant in autumn, better use of rainfall, and avoidance of late-season heat and drought stresses, autumn planting leads to better plant stability and yield compared to spring planting. In chickpeas, autumn sowing increases plant height and nitrogen fixation. Scientists believe that autumn cultivation of chickpea leads to higher yields due to the longer vegetative growth period and coincides with the reproductive growth period with favorable humidity and temperature conditions. On the other hand, studies have shown that in severe freezing temperatures in cold regions, chickpea has a lower tolerance threshold than autumn cereals. This study aimed to evaluate the freezing tolerance of chickpea genotypes -desi type- in field conditions to select superior genotypes for autumn cultivation.

This study was conducted in the research farm station of the Faculty of Agriculture, the Ferdowsi University of Mashhad in 2018. In this study, 255 desi type genotypes and a Kabuli type genotype (Saral) as control were evaluated in a Randomized Complete Block Design with three replications. Seeds were provided from the Mashhad Chickpea Collection (Seed Bank of Research Center for Plant Sciences, Ferdowsi University of Mashhad). Planting was done in October with a density of 30 plants per square meter. Irrigation was done in three stages including immediately after planting, 14 days after the first irrigation, and at the flowering stage. To determine survival percentage, the number of plants for each genotype was counted 30 days after emergence and immediately after winter. Genotypes were classified into four groups (0-25, 26-50, 51-75 and 76-100% survival). Plant height, plant length, lowest pod height, number of branches, number of pods per plant, percentage of filled pods, plant dry weight, grain weight per plant, 100-seed weight, biological yield, grain yield, and harvest index were measured at the end of the growing season.

The lowest minimum temperature during the growing season was -12°C. Results showed that among 255 genotypes, 25 genotypes were lost before freezing stress and 20 genotypes were lost by freezing stress. Significant differences were observed among the genotypes in terms of plant height, plant length, lowest pod height, number of branches, number of pods per plant, percentage of filled pods, plant dry weight, seed weight per plant, 100-seed weight, biological yield, grain yield, and harvest index. The survival percentage of 39 genotypes was between 76 to 100%, 75 genotypes between 51 to 75%, 61 genotypes between 26 to 50%, and 55 genotypes less than 25%. Ten genotypes (MCC373, MCC658, MCC755, MCC212, MCC83, MCC864, MCC371, MCC756, MCC749 and MCC885) had a survival percentage higher than 90%. Plant height in 21 genotypes was higher than 50 cm and the lowest pod height in 47 genotypes was more than 15cm. The number of branches per plant increased as the survival range increased. Also, in different survival ranges, grain yield decreased as survival percentage decreased. The average grain yield in the survival range of 100-76% was 257 g.m-2, which was 24%, 2.5, and 8.6 times higher than the survival ranges of 51-75, 26-50, and 0-25%, respectively. No significant difference was found among survival ranges of 100-76, 75-51, and 50-26% according to the harvest index.

The results of cluster analysis of chickpea genotypes desi type under autumn cultivation showed that 230 studied genotypes were divided into four groups. The four groups included 106, 24, 43, and 57 genotypes, respectively. Standardized canonical coefficients of all traits except, the percentage of filled pods, seed weight per plant, 100-seed weight, and harvest index were significant in the first canonical diagnostic equation. These results show that these traits have the greatest impact on the diversity between genotypes. Based on the results of the analysis of the variance of groups, except for the percentage of filled pods and harvest index, a significant difference was observed between the groups in all studied traits. A comparison of the means of the groups showed that the genotypes of the second group had the highest mean survival percentage and then the fourth group was in the next rank. The difference between the means of these two groups with the total mean was 17.7 and 16.4%, respectively. The genotypes of the second group were superior to the genotypes of the other groups in terms of biomass yield and grain yield and produced 1252 and 606 g.m-2 more than the total average, respectively, then the genotypes of the fourth group were superior to the genotypes of the other groups. In general, due to the high yield in the cold-tolerant genotypes, autumn cultivation of desi-type chickpeas seems to be economical.