Genetic Basis of Heterosis for Yield and Related Traits in Pea (Pisum sativum L.)

Heterosis over better parent was estimated for seed yield and related traits in 16 crosses of pea. To ascertain the genetic causes responsible for the observed heterosis in pea, the estimates of genetic parameters realized from first degree (generation mean analysis) and second degree statistical (modified TTC) models have been used. Only one cross (HUP 9 X Pusa 10) was considered for generation mean analysis. In case of modified triple test cross analysis, 15 pure lines of pea were crossed to three testers viz., HUP 9 (L₁), Pusa 10 (L₂) and F₁ of HUP 9 x Pusa 10 (L₃) to produce 3n families. Significant average heterosis over better parent was evidenced for plant height, pods per plant and seed yield per plant. Heterosis for seeds per pod and seed weight was negative or low. The generation mean analysis revealed that the observed heterosis for seed yield per plant and pods per plant was mainly due to over dominance. Further, overdominance and higher magnitude of epistatic components [h] and [I] as was observed in modified triple test cross analysis, could be the possible cause of heterosis for seed yield per plant and pods per plant. For days to flowering, partial dominance could be responsible for the higher heterosis for earliness.