GENETIC DIVERSITY AND FATTY ACID COMPOSITION ANALYSIS OF MUSTARD (Brassica rapa L.)

Abstract

An experiment on Brassica rapa L. was conducted to determine the genetic variability, character association, genetic diversity and analysis of fatty acid composition of 14 mustard varieties. The research was conducted during the rabi season of 2016-2017 in research farm of Sher-e-Bangla Agricultural University, Dhaka. The analysis of variance showed significant differences among the varieties for all traits except number of primary branches/plant. The phenotypic variances were higher than the genotypic variances for all the traits. High phenotypic variance and high genotypic variance were found for number of secondary branches per plant, number of siliqua per plant, number of seeds per siliqua and seed yield per plant. High heritability coupled with high genetic advance as percent of mean were noticed for days to first flowering, days to 50% flowering, number of secondary branches per plant, number of siliqua per plant and number of seeds per siliqua indicating the effect of additive genes in controlling the traits. Significant positively correlation at both phenotypic and genotypic levels was observed in number of siliqua/plant with number of secondary branches, days to maturity with siliqua length, number of seeds per siliqua with days to first flowering, days to 50% flowering and thousand seed weight. The path analysis revealed days to first flowering, number of secondary branches per plant and 1000 seed weight had direct positive effect on seed yield/plant indicating these were the main contributors to yield/plant. The varieties were grouped into five diverse clusters found in PCA and D 2 analyses. The highest inter cluster distance was found between cluster II and cluster V (20.41) indicating hybridization among these varieties may produce a wide spectrum of segregating population. Significant variations were present in the fatty acid components analysis extracted from oil of six selected varieties. Higher oil content (42.42%) was observed in BARI sarisha-14 variety. The saturated fatty acids viz. myristic, stearic and palmitic acids were less than 7%, was observed in oil of Sonali sarisha and BARI sarisha-14. The total monounsaturated

fatty acids were ranged from 62.74% in BARI sarisha-15 to 69.51% in Sonali sarisha. The highest oleic acid and eicosenoic acid were obtained in Maghi (21.06%) and Improved Tori (9.08%) respectively. The anti-nutritional factor, erucic acid content was found lowest in Maghi (35.53%) and BARI sarisha-15 (36.98%) varieties. The essential fatty acids, linoleic and linolenic were found highest in the seed oil of BARI sarisha-15 (17.10%). As a whole, the results suggest that for further improvement of the crop hybridization among BARI sarisha-14, BARI sarisha-15, Maghi, Sonali sarisha and Improved Tori would create noble segregates with low erucic acid and yield potential recombinant lines for further breeding program.