| Abstract |
The study entitled “Identification of core set in fodder cowpea (Vigna <br/>unguiculata (L.) Walp) germplasm accessions” was carried out at Department of Plant <br/>Breeding and Genetics, College of Agriculture, Vellayani during December 2020-May <br/>2021 with the objective of assessing variability in the fodder cowpea germplasm <br/>accessions, constitute a representative core set and to evaluate the representativeness of the <br/>core set vis a vis base collection.<br/>143 fodder cowpea (Vigna unguiculata (L.) Walp) genotypes collected from <br/>NBPGR, New Delhi and bush type cowpea varieties of KAU along with 3 check varieties <br/>formed the base collection. There were 2 experiments, in which experiment 1 was <br/>evaluation of seedlings and experiment 2 was field evaluation of fodder cowpea variability <br/>and identification of core set. Experiment 1 i.e., seedling evaluation of 146 accessions was <br/>carried out in Completely Randomized Design with 2 replications. Various seedling <br/>characters such as germination %, shoot length, root length, seedling length, fresh weight <br/>per plant, dry weight per plant, vigor index and relative growth index were observed. Oneway ANOVA and Principal Component Analysis were also carried out using GRAPES <br/>software of KAU. All the genotypes significantly differ each other in all the character. The <br/>biplot was constructed using the first two PC’s, in which genotypes like EC723987, <br/>IC39908, IC402125, IC398992, NR/18-105 showed maximum scattering and <br/>demonstrated maximum genetic divergence among the accessions. <br/>Evaluation of variability was carried out in the field using Augmented Block <br/>Design. The seeds were sown at a spacing of 15 cm x 30 cm during January 2021. Every <br/>accessions were sown in two rows of ten plants each and the check varieties were replicated <br/>in all the 13 blocks. The cultural operations were done according to the recommendation <br/>of KAU Package of Practices. <br/>The genotypes were evaluated for 20 biometric characters and seven qualitative <br/>characters. The genotypes showed significant differences for all the characters except <br/>secondary branches per plant and stem girth. Biochemical character such as crude protein <br/>and crude fibre content for top genotypes which showed high green fodder yield per plant <br/>was estimated and all the treatments significantly differ from each other. Genetic parameter <br/>analysis was performed for twenty biometric characters and for all the characters PCV <br/>values were higher than GCV values indicating the influence of environment. The <br/>phenotypic and genotypic coefficient of variation were maximum for Leaf Area Index <br/>(LAI), green fodder yield per plant, stem dry weight per plant, leaf dry weight per plant, <br/>seed yield per plant etc. and minimum for days to maturity. Heritability and genetic <br/>advance was high for number of leaves per plant, LAI, green fodder yield per plant, stem <br/>dry weight per plant, leaf dry weight per plant, plant height, seed yield per plant etc.<br/>The correlation studies revealed positive correlation of leaf dry weight, stem dry <br/>weight, dry matter yield, LAI with green fodder yield per plant. A negative significant <br/>correlation was seen in between stem girth and days of 50% flowering. <br/>The path analysis provides information on contribution of traits by partitioning <br/>the total correlation into direct and indirect effects. Path analysis of fourteen characters <br/>revealed high and positive direct effect of stem dry weight, leaf dry weight, primary <br/>branches per plant, days of 50% flowering on green fodder yield. High indirect effect on <br/>green fodder yield was observed for many characters. Residual effect obtained was 17.6% <br/>which indicates that 82.4% variation in yield was contributed by characters under study.<br/>Cluster analysis was done using UPGMA (Unweighted Pair Group Method with <br/>Arithmetic Mean) method. The 146 accessions were grouped into 30 clusters. Cluster X <br/>with 21 genotypes was the largest followed by cluster XI (20 genotypes), cluster XIV (13 <br/>genotypes), cluster I (12 genotypes), cluster VII (10 genotypes), cluster II (8 genotypes), <br/>cluster IV (7 genotypes), cluster XII and cluster XXVI1 (6 genotypes each), cluster XVII <br/>(5 genotypes), cluster VI, cluster VIII, cluster XIX and cluster XXIX (4 genotypes each), <br/>cluster XIII (3 genotypes), cluster IX, cluster XV, cluster XVIII and cluster XXIV (2 <br/>genotypes each) and the remaining were solitary clusters.<br/>Core analysis was carried out using power core (v.1.0) software. The core set <br/>formed comprised of 24 accessions (16 per cent) of the entire collection. A comparison of <br/>geographical distribution of accessions in core set and base collection were done. The base <br/>collection comprised of accessions from India- 34%, Philippines- 14%, Nigeria, USA, <br/>African countries, Europe, Australia etc. The core collection contained accession mostly <br/>from India with representation from Philippines, Nigeria, USA, Chad, Hungary. A<br/>comparison of frequency distribution of qualitative traits in core and base collection were <br/>estimated using chi square test and all the characters showed non significance among each <br/>other indicated the true representation of core with respect to qualitative characters. <br/>Comparison of statistical parameters viz., mean, range and variance with respect to 20 <br/>quantitative traits in both core set and base collection were also done using two tailed t-test <br/>for comparing mean and homogeneity test (F test) for comparison of variance. In this case <br/>also all the character showed no significant difference between the two population revealed <br/>that the core set included as much genetic diversity as possible. Phenotypic diversity among <br/>core and base was assessed using Shannon-Weaver diversity index (H‟). All character has <br/>obtained higher H‟ value with comparable overall mean of 2.008±0.11 and 2.138±0.12 <br/>respectively. Percentage of diversity in core set over base collection was 101.5%.<br/>The core set seems to be a good subset of fodder cowpea germplasm accessions <br/>which covers most of all existing diversity in base collection and eliminated the duplicates. <br/>This can form a great population which can further utilize for various breeding aspects. |
