Dr. P. JAGAN MOHAN RAOMUNAZZA MOIN2024-09-242024-09-242024-02-22https://krishikosh.egranth.ac.in/handle/1/5810214885The present investigation entitled “Genetic diversity studies for yield and yield component traits under high temperature stress in chickpea (Cicer arietinum L.)” was undertaken to assess the nature and magnitude of genetic variability, heritability and genetic advance, genetic diversity for yield attributes and molecular diversity among 50 chickpea genotypes including four checks. The field experiment was laid out in a Randomized Block Design with three replications at Seed Research and Technology Centre, Rajendranagar, Hyderabad during Rabi, 2022-2023 and observations were recorded on 13 characters. The analysis of variance (ANOVA) for the normal and late sown conditions revealed highly significant differences among 50 chickpea genotypes indicating the presence of high variability among the 50 chickpea genotypes. Variability studies revealed that PCV and GCV values were high for number of seeds plant-1, followed by number of filled pods plant-1, seed yield plant-1 and number of pods plant-1 under both normal and late sown conditions indicating higher magnitude of variability among the genotypes studied and provided significant opportunity for the improvement of these features by selection. High heritability coupled with high genetic advance as per cent of mean GAM (%) was exhibited by the traits such as number of seeds plant-1, number of filled pods plant-1, seed yield plant-1, number of pods plant-1, number of primary branches plant-1, 100 seed weight, number of secondary branches plant-1 and plant height in both normal and late sown conditions indicating the predominance of additive gene action for these characters. Under both normal and late sown conditions correlation studies revealed that seed yield plant-1 had shown highly significant and strong positive phenotypic correlation with the traits filled pods plant-1, number of pods plant-1, number of seeds plant-1 and harvest index. Therefore, selection for above mentioned yield and yield component traits could directly lead to seed yield improvement and path coefficient analysis revealed that among all the traits number of filled pods plant-1 has shown high value of positive direct effect on seed yield plant-1 followed by number of pods plant-1, 100 seed weight, days to pod initiation, number of primary branches, harvest index and number of seeds pod-1 under normal sown conditions. Under late sown conditions the traits number of filled pods plant-1 has shown high value of positive direct effect followed by harvest index, 100 seed weight, days to pod initiation, number of secondary branches plant-1, number of primary branches plant-1, plant height, number of seeds plant-1, and number of seeds pod-1. Therefore, these characters must be included in the key selection criteria for breeding high-yielding cultivars for normal and late sown conditions respectively. The genotypes were grouped into four clusters based on their D2 values under normal sown conditions. Cluster I comprising the 47 genotypes was the largest and remaining all the three clusters were solitary clusters. The maximum inter-cluster distance (530.57) was observed between the clusters II and IV followed by clusters III and IV (381.03). Under late sown conditions three clusters were formed based on their D2 values, with cluster I having 48 genotypes and intra-cluster distance (114.88) and remaining two clusters were solitary clusters. The maximum inter-cluster distances (650.72) were observed between the clusters I and III and followed by clusters I and II with (228.91). Molecular characterization using 40 SSR markers revealed that 28 markers exhibited polymorphism resulting in the identification of a total of 78 alleles. The number of alleles generated per locus by each marker within the chickpea genotypes ranged from 2 to 6. The PIC values among the SSR loci varied with a range of 0.0384 exhibited by H1B17 to 0.576 exhibited by NCPGR 23 with an average of 0.371. Clustering of genotypes using UPGMA resulted in grouping the genotypes into 19 clusters. The check ICC10685 found in the solitary clusters of both the molecular and morphological (at both normal and late sown conditions) dendrograms representing that some diversity is present in this genotype at both molecular and morphological level. The results of mean performances suggests that the genotypes ICCV 191152, ICCV 191218, ICCV 191232, ICCV 191256 were found superior for seed yield under both normal and late sown conditions and the genotypes ICCV1218, ICCV191232 and ICC10685 were found superior for traits number of pods plant-1, number of filled pods plant-1, number of seeds plant-1 under both conditions. Hence, these genotypes could be used in the breeding programmes for the development of high yielding chickpea cultivars suitable for both timely and late sowings.EnglishThesis