Expression of heterosis and residual heterosis for traits of earliness and yield in cross combinations of cucumber (Cucumis sativus L.) developed by introgression of indigenous and exotic sources

Abstract

Manifestation of residual heterosis in the F2 generation would offer the scope, as the growers need not to get the highly priced F1 seed every year. Therefore, an attempt has been made to estimate the magnitude and direction of residual heterosis for different horticultural traits in F2 generation of cucumber so that F2 seeds may be utilized to get heterotic effect with lower cost of seed production. The present study comprised of experimental material of F1 and F2 population of 18 crosses, developed by crossing 6 lines and 3 testers. All the parents, 18 each of F1 and F2 along with the standard check Pusa Sanyog were evaluated for their comparative genetic evaluation. The analysis of data showed highly significant differences for all the traits under study. First filial generation (F1) hybrid combination LC- × K-75 (104.93, 52.43 %) followed by LC-2-2 × Poinsette (91.54, 30.78 %) exhibited maximum estimates of heterosis for their respective better parent and standard check, whereas, residual heterobeltiosis and economic heterosis was maximum in the cross combination LC-2-2 × Poinsette (67.50, 24.47 %) followed by LC-12-4 × Poinsette (64.86, 22.51 %), LC-1-1 × K-75 (63.85, 35.45 %) and LC-1-1 × Poinsette (37.90, 13.99 %) respectively. Two cross combinations viz., LC-1-1 × K-75 and LC-2-2 × Poinsette were found promising for yield and yield contributing traits in both F1 and F2 generation. Presence of hybrid vigour for fruit yield in F2 generations (residual heterosis) is attributed to additive and additive × additive gene interaction and such crosses were expected to give superior segregants, which may be handled through pedigree breeding method for further improvement.