Combining ability and heterosis for bud fly infestation and seed yield and it's attributes in linseed (Linum usitatissimum L.)

Abstract— Four bud fly-resistant germplasm lines viz., EC-1424, GS-234, IC-15888, and JRF-5 were crossed with three testers (Neelum, Neela, and Shekhar) in a line × tester mating design to develop 21 F₁ and 21 F₂ crosses. The study was undertaken to estimate combining ability and heterosis in linseed (Linum usitatissimum L.) for bud fly infestation, seed yield, and related traits. The analysis of variance for general combining ability (GCA) and specific combining ability (SCA) was highly significant in both F₁ and F₂ generations. Based on per se performance and GCA effects, the best general combiners identified in both F₁ and F₂ generations were Neela for days to flowering and bud length; IC-15888 for sepal thickness, maturity duration, and bud fly infestation at the dough stage; Shekhar and Neela for grains per capsule; Neela for test weight; GS-234 and Neelum for oil content. However, no common general combiner was found for bud width, capsules per plant, and seed yield per plant across both generations. For capsules per plant, Shekhar was a good combiner only in the F₁ generation. Heterosis over the superior parent for bud fly infestation at the dough stage ranged from –99.03% (EC-1424 × JRF-5) to –48.59% (Shekhar × Neelum) in the F₁ generation. Out of 21 crosses, 20 crosses exhibited significant negative economic heterosis for this trait. The top five promising crosses were EC-1424 × JRF-5, EC-1424 × Neela, GS-234 × IC-15888, GS-234 × JRF-5, and IC-15888 × Shekhar. Only one cross (EC-1424 × Shekhar) showed significant positive heterosis for bud fly infestation. For seed yield per plant, heterosis over the economic parent ranged from 28.64% (JRF-5 × Neelum) to 51.90% (Shekhar × Neelum) in the F₁ generation. Among all crosses, six crosses exhibited significant positive heterosis. These cross combinations may serve as potential genetic resources in future linseed breeding programs aimed at improving yield and bud fly resistance.