Genetic studies on incidence and severity of economically important insect-pests and diseases in F₁ and F₂ generations of cucumber

Combining ability, gene action and heterosis for incidence and severity of fruit fly, and powdery and downy mildew were worked out in F₁ and F₂ populations of 18 crosses, developed by crossing six lines and three testers in cucumber. The experimental results revealed that among the parents, LC-1-1, LC-2-2, CGN-20515, Poinsette and K-75 were found superior on the basis of mean performance and GCA effects, while the cross combinations, LC-1-1 × K-75, LC-2-2 × Poinsette, CGN-21585 × Poinsette, LC-12-4 × Poinsette and CGN-20515 × Poinsette were found superior based on mean performance, combining ability and heterotic response in F₁ and F₂ generations. Therefore, these parents and hybrid combinations can be utilized for the development of hybrids/varieties having resistance to these biotic stresses in cucumber. Further, gene action studies and contribution of lines × testers interactions revealed predominant role of nonadditive gene action for the control of different diseases under study, hence heterosis breeding can be exploited commercially for disease resistant hybrid development in cucumber.