Studies on Genetic Diversity Assessment and Character Association in Indian Mustard (Brassica Juncea L. Czern & Coss) Genotypes for Agro-morphological Traits

Abstract

Studies on Genetic Diversity Assessment and Character Association in Indian mustard (Brassica juncea L.Czern & Coss) Genotypes for Agro-morphological Traits. The present investigation entitled “Studies on Genetic Diversity Assessment and Character Association in Indian mustard (Brassica juncea L. Czern & Coss) Genotypes for Agro-morphological Traits” was carried out at the Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, U.P. during Rabi 2019-20 to analyze the genetic variability, heritability, genetic advance, correlation, path analysis and genetic divergence for 14 quantitative traits. The experiment is performed with 45 genotypes of mustard using a Randomized Complete Block Design with three replications. Each genotype was planted in three rows of 5.0 m length, with a 45 cm row-to-row spacing and a 15 cm plant-to-plant spacing. The observations were recorded for the 14 characters viz., days to 50% flowering, days to maturity, plant height (cm), number of primary branches per plant, number of secondary branches per plant, length of main shoot (cm), number of siliquae on main shoot, siliqua length (cm), number of seeds per siliqua, test weight (g), oil content (%), harvest index (%), biological yield per plant (g) and grain yield per plant (g). The analysis of variance (ANOVA) revealed extremely significant differences across genotypes, indicated that sufficient amount of genetic variability existed among the present set of breeding material. Phenotypic coefficient of variance (PCV) and genotypic coefficient of variance (GCV) were moderate (10-20%) for plant height, number of primary branches per plant, number of secondary branches per plant, length of main shoot, biological yield per plant, test weight, harvest index and grain yield per plant. The characters plant height, grain yield per plant, length of main shoot, number of secondary branches per plant and biological yield per plant shows high heritability coupled with high genetic advance in percent of mean.While the characters number of primary branches per plant, test weight, number of siliquae on main shoot, and siliqua length shows high heritability with moderate genetic advance. Highly significant and positive association was displayed by grain yield per plant with length of main shoot, number of seeds per siliqua, plant height, number of secondary branches per plant, biological yield per plant, test weight, number of siliquae on main shoot, number of primary branches per plant, siliqua length and harvest index at both the genotypic and phenotypic levels. It indicated that by improving these traits, improvement in grain yield per plant might be achieved under selection. The phenotypic and genotypic path coefficients revealed that biological yield per plant, harvest index, plant height, siliqua length, length of main shoot, and oil content all displayed highly positive direct contribution towards grain yield per plant. Whereas biological yield per plant and harvest index may be improve the grain yield per plant indirectly. Based on D2 value, 45 genotypes of Indian mustard included in study were grouped into seven clusters. The largest cluster was Cluster II, and it consists of 11 genotypes followed by cluster VI with nine genotypes, cluster III and IV with eight genotypes, cluster I, V and VII with three genotypes. Cluster I shows the maximum intra cluster distance followed by cluster VI, cluster VII, cluster III, cluster V and cluster IV while the cluster II shows minimum intra cluster distance. Genotypes belonging to cluster I (UJM-15, UJM-2 and UJM-4) exhibited maximum genetic diversity within the cluster as compared to the genotypes belonging to other clusters. Hence, hybridization might be taken up among these genotypes (UJM-15, UJM-2 and UJM-4) for obtaining desirable segregants for the yield and yield component traits. The inter cluster distance found maximum between cluster I and VII, which shows the greater genetic divergence between the genotypes associated to these clusters and crosses involving genotypes viz., UJM-15, UJM-2 and UJM-4 of cluster I; UJM-14, Pusa Mustard-22 and GM-2 of cluster VII is recommended. Crosses within the above combinations are expected to provide enough genetic variability among the population in the segregating generations. Hence, selection of better plant type might be made for yield and yield component traits. High hybrid vigor for yield also can be obtained by involving genetically diverse genotypes in the crosses which might be useful in the development of hybrids in mustard.