Heterobeltiosis and inbreeding depression for yield and agronomic traits in Indian Mustard (Brassica juncea L. Czern. & Coss.) across two environments

Abstract

The four genetically diverse parental lines were crossed with well-adapted released varieties to generate promising hybrids. The results demonstrated significant variability in heterobeltiosis and inbreeding depression across different crosses and two environments (E1 and E2). In PR 36 × Rohini, seed yield per plant exhibited negative heterobeltiosis (-12.37% in E1 and -16.55% in
E2), suggesting hybrid weakness. However, traits like siliquae per plant (19.51%) and number of seeds per siliqua (4.65%) showed positive heterobeltiosis, indicating genetic potential for selection. Inbreeding depression was notably high for plant height (4.10%) and seed yield (19.77%) in E2, suggesting genetic instability. In PRE 11 × CS 60, moderate to high heterobeltiosis was observed for the number of secondary branches per plant (10.52%) and siliquae per plant (29.37%) in E2. However, seed yield per plant (-16.29%) exhibited negative heterobeltiosis, and inbreeding depression was significantly high (-28.61%) in E1, indicating a strong impact of selfing on yield- related traits. PRE 15 × CS 58 exhibited high heterobeltiosis in siliqua length (36.36%) and seeds per siliqua (9.30%), indicating a high genetic potential for selection. However, seed yield per plant showed negative heterobeltiosis (-8.87% in E1, -1.07%
in E2), and inbreeding depression was notable for seed yield (12.94%) and plant height (5.72%), emphasizing the need for hybrid stabilization. PRL 26 × Giriraj showed negative heterobeltiosis in days to flowering and plant height, but positive heterosis for siliquae per plant (3.59%) and seed yield per plant (6.18%) in E2. The highest inbreeding depression was observed for seed yield (-35.18%) in E1, indicating genetic susceptibility to selfing.