Genetical studies in parthenocarpic cucumber

Abstract

newline The present investigation entitled Genetical studies in parthenocarpic cucumber (Cucumis newlinesativus L.) was carried out at the Experimental Farm, Department of Vegetable Science and newlineFloriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur to gather information on newlinecombining ability, gene action and magnitude of heterosis in parthenocarpic cucumber. Eight parental newlinelines were used to develop F1 hybrids through half diallel mating design (excluding reciprocals). All newlineparental lines and hybrids were evaluated along with standard check Kian in RBD with three newlinereplications under modified naturally ventilated polyhouses during spring-summer seasons of 2020 and newline2021. Genetic diversity of eight parental lines was assessed using SSR markers to identify the diverse newlineparents. PCA revealed 54.04 per cent variation as justified by first three principal components and newlinemaximum genetic variation (21.10%) was contributed by PC1. Eight cucumber genotypes were newlinegrouped into two clusters and both the clusters were divided into 2 sub clusters (NTSYS software) and newlineDARwin software exhibited three clusters out of which cluster II was further divided into two sub newlineclusters and was also confirmed by population structure. The analysis of variance indicated significant newlinedifferences among genotypes (G) for fruit yield and other component traits in all the environments. newlineSignificant differences for environment (E) and G × E interaction for most of the traits indicated the newlinerole of environment on the performance of genotypes/crosses. Combined analysis of variance also newlineindicated that mean squares due to parents, hybrids and parents vs. hybrids were significant for most of newlinethe traits. Variances due to GCA, SCA and their interaction with environment were significant for most newlineof the traits, indicating the importance of testing parents as well as hybrids across environments. The newlinetop cross combinations identified on the basis per se performance were DDPCG1 × DDPCG2, newlineDDPCG1 × DDPCG5, DDPCG1 × PPC-2 and DDPCG1 × PPC-3 for fruit yield and its component newlinetraits under protected environment. Parents DDPCG1, DDPCG4, PPC-2 and DDPCG5 were observed newlineto be good general combiners for earliness, fruit yield and its component traits. Cross combinations newlineviz., DDPCG4 × DDPCG5, DDPCG1 × PPC-2, DDPCG1 × DDPCG5, PK-1 × PPC-3 and DDPCG1 × newlineDDPCW1 were the most promising crosses on the basis of SCA effects for yield and its related traits. newlineFor most of the traits, there was preponderance of non-additive gene action which reaffirms the newlineimportance of hybrids in cucumber. A wide variation in magnitude and direction of heterosis was newlinenoticed for majority of the traits with maximum manifestation for number of fruits per plant and newlinemarketable yield per plant. Hybrids DDPCG1 × DDPCG2, DDPCG1 × DDPCG5, DDPCG1 × PPC-2, newlineDDPCG1 × PK-1 and DDPCG1 × DDPCW1 were the most promising crosses with significant newlineeconomic heterosis for yield and yield related traits. Based on per se performance, SCA effects and newlineheterosis, DDPCG1 × DDPCG2, DDPCG1 × DDPCG5, DDPCG1 × PPC-2, DDPCG1 × PK-1 and newlineDDPCG1 × DDPCW1 were the most promising hybrid combinations for protected environment.