SELECTION IN F 2 POPULATIONS BASED ON GENETIC VARIABILITY OF RAPESEED (Brassica rapa L.)

Abstract

An experiment was carried out with 39 F 2 populations of Brassica rapa L. at the experimental field of Sher-e-Bangla Agricultural University, Dhaka during November 2019 to February 2020 considering thirteen yield contributing characters. To study 39 F 2 populations, the magnitude of variations in the characters, correlation, heritability, genetic advance, direct and indirect effect of different characters on seed yield per plant were taken under analysis. Significant variation was observed among all populations for all the characters. For all of the traits, the phenotypic variance was higher than the genotypic variation. Number of secondary branches per plant, total siliqua and yield per plant showed high genotypic and phenotypic coefficient of variance. Days to first flowering, days to 50% flowering and days to 80% flowering showed high heritability coupled with low genetic advance and low genetic advance in percentage of mean. Study on correlation revealed that yield/plant had significant and positive association with number of primary branches per plant; number of secondary branches/plant and total siliqua but non-significant and negative association with days to first flowering and yield per plant at both phenotypic and genotypic level. Path co-efficient analysis revealed that number of seeds per siliqua showed highest positive direct effect on yield/plant followed by days to maturity, days to 80% flowering, plant height, total siliqua and siliqua length. On the other hand, number of primary branches/plant, number of secondary branches/plant, days to 50% flowering, root length and thousand seed weight had negat ive direct effect on yield per plant. Selection was conducted among 39 F 2 populations of Brassica rapa L. to find out the early maturing and the highest yielding populations. 12 populations such as P5XP1, P5XP3, P1XP2, P1XP7, P6XP5, P7XP3, P3XP5, P3XP1, P3XP4, P4XP2, P5XP2, and P5XP7

were selected for high yielding and early maturing from the 39 populations for further trial.