GENETIC COMPONENTS AND HETEROSIS ANALYSIS OF F 2 AND BC 1 F 1 POPULATIONS IN Brassica juncea L.

Abstract

The investigation was conducted to estimate the phenotypic performance, and to assess the genetic components, variability, heterosis and inbreeding depression among the twentyone

F 2 and six BC 1 F 1 populations of Indian mustard (Brassica juncea). The research was conducted at Sher-e-Bangla Agricultural University during rabi seasons of 2021-22 in a randomized complete block design with three replications. All the twelve traits studied here showed significance variation among the F 2 populations. The phenotypic performance of the F 2 populations viz., G9, G12, G13, G16 and G4, G20, G17 showed comparatively better mean performance in terms of early maturity, and yield, respectively than the rest of populations. The populations G1 had the lowest days for acquiring 80% maturity (104.33 days), while G12 had the shortest plant height (126 cm) among the 21 F 2 populations, while G17 produced the highest yield (15.6gm) per plant among the twenty-one F 2 populations. All of the twelve traits displayed high heritability (h 2 b) in the broad sense e.g., heritability for days to siliqua maturity (73.70%), for plant height (90.90%), for days to first flowering (82.50%), and for seeds per siliqua (82.27%)), indicating that high genotypic effects accounted for the majority of total variation. The correlations study showed that yield per plant had positively and significantly correlation with number of primary branches, number of secondary branches, siliqua length, slilqua per plant. The F 2 populations G4, G14, G21 showed highest significant negative heterosis for day to maturity, while F 2 populations G8, G13, G17, G19, G20 showed highest significant positive heterosis for yield indicated that these populations might be considered for selection for earliness and yield improvement. G1, G13, G18, G20 (as these populations show highest positive inbreeding depression in case of earliness and plant height) are the considered potential lines for earliness, short stature) while G2, G8, G13, G17 had minimal inbreeding depression in terms of siliqua per plant, siliqua length and yield per plant, hence these are the genotype desired for higher yield. Among the backcrossed population, the combinations (P5×P6) × P5 showed the best result for yield contributing trait, early maturity and short stature. Altogether, the F 2 populations viz., G4, G5, G8, G13, G17, G19, and G20 might be chosen as potential populations for selection of early-maturing, and high-yielding lines in future.