GENETIC VARIABILITY AND CHARACTER ASSOCIATION IN BC1 F9 POPULATION OF Brassica napus L

Abstract

Thirty genotypes of Brassica napus L. were evaluated based on a randomized complete block design with three replications at the experimental field of Sher-eBangla Agricultural

University, Dhaka, to study the variability, correlation, and path analysis during the November 2019 to March 2020 growing seasons. The genotypes were found significantly variable for all the characters. Comparatively phenotypic variance was higher than the genotypic variance for all the characters studied. The high genotypic coefficient of variation and phenotypic coefficient of variation value were observed for yield per plant (g). The maximum difference between the phenotypic and genotypic coefficient of variation was 30.31 and 13.82. Days to 50% flowering, days to maturity, thousand seed weight (g), and yield per plant (g) all showed high heritability along with genetic advance in percentage of mean, indicating additive gene expression on this trait. The significant positive correlation with yield per plant was found in seeds per siliquae, thousand seed weight (g), and yield per plant in both genotypic and phenotypic levels indicating the importance of these traits in selection for increasing yield and were identified as yield attributing characters. Thus, selection can rely upon these characteristics for the genetic improvement of the yield of B. napus. According to path analysis, the number of secondary branches per plant had the lowest positive direct effect and thousand seed weight (0.684) had the highest positive direct effect (0.151). Days to 50% flowering (0.194), plant height (0.204), number of secondary branches per plant (0.151), siliqua length (0.247), seeds per siliqua (0.268), and thousand seed weight (0.684) all had a positive direct impact on yield per plant (g), suggesting that direct selection based on these traits may be useful in the development of high yielding B. napus varieties. Considering genotypic variance and agronomic performance genotypes and based on objectives G8, G9, G18, G1, G28, and G14 might be suggested for future breeding programs.