MSc

The study entitled “Genetic variability studies in grain cowpea (Vigna unguiculata (L.) Walp.) was carried out at Farming Systems Research station, Sadanandapuram during December, 2019 – March, 2020 with the objective to evaluate and select shade tolerant grain cowpea genotypes suited to the coconut based homesteads.
The 33 grain cowpea genotypes collected from research stations under KAU, AICRP centre and agricultural universities of different states were evaluated in coconut based homestead garden where coconuts are of age 30 – 40 years, in randomized block design replicated thrice. The seeds were sown on raised beds of (3 х 1.5) m2 size at a spacing of 30 cm х 15 cm and cultural operations and plant protection measures were adopted as per the “Package of Practices Recommendations: Crops 2016” of Kerala Agricultural University.
The average light intensity in the experimental field recorded was 0.719 W/m2 resulting in shade of 33.49 per cent. The genotypes were evaluated for biometric and physiological characters associated with shade tolerance and quality character of seed. The genotypes showed significant differences for all the characters studied. Genetic parameter analysis was performed for twelve characters and for all the characters PCV values were higher than GCV values indicating the influence of environment. The phenotypic and genotypic coefficients of variation were maximum for seed yield per plant and minimum for protein content. Heritability was high for all the twelve characters and genetic gain was high for all the characters except days to 50% flowering and protein content.
The correlation studies revealed positive correlation of the characters days to 50% flowering, number of pods per plant, number of seeds per pod, crop duration, harvest index, LAD at flowering, CGR at flowering and protein content with seed yield. The path analysis provides information on contribution of traits by partitioning the total correlation into direct and indirect effects. Path analysis of the eight characters showing significant correlation with seed yield revealed high positive direct effect of the characters number of pods per plant and harvest index on seed yield.
High indirect effect on seed yield was observed for CGR at flowering through number of pods per plant.
Cluster analysis aids in the selection of genetically divergent parents for hybridization programme which results in greater heterosis. Cluster analysis using Mahanalobis D2 statistic following Tocher’s method grouped the 33 genotypes into nine clusters. Cluster II with 10 genotypes was the largest followed by cluster I and cluster V (8 genotypes each), cluster III (2 genotypes) and clusters IV, VI, VII, VIII, IX which were solitary clusters. Highest intra cluster distance was recorded among the genotypes of cluster V and lowest in cluster III whereas highest inter cluster distance was observed between the genotypes of the clusters III and IX followed by clusters VI and IX.
The present study revealed that the variety Sreya recorded highest seed yield under partially shaded condition. The genotypes CHESCP-03, CHESCP-17 and CHESCP-32 are medium in duration with shade tolerance and higher yield, hence suited to the coconut based homesteads. Among the early duration types, Subhra recorded the highest yield. Genotypes CHESCP-19 and KYLMVU-6 recorded yield on par with the shade tolerant genotypes CHESCP-03, CHESCP-17 and CHESCP-32. Subhra and the late duration varieties Sreya, CHESCP-19 and KYLMVU-6 recorded low values for shade tolerant parameters and there is scope for improving the yield by hybridization with shade tolerant varieties. Subhra and CHESCP-21 were found to be superior for protein content. As quality of a pulse variety is determined by the protein content, these genotypes can be used as parents in quality improvement programmes. The superior genotypes identified in the study can be recommended for cultivation and future breeding programs.