Heterosis in relation to molecular diversity in pigeonpea [Cajanus cajan (L.) Millsp.]

Pigeonpea is the only grain legume crop where hybrid vigour has been exploited commercially. For sustaining this technology, it is imperative that information about the genetic nature of hybrid vigour is generated and new highyielding hybrids are bred at regular intervals. In this context, a set of genetic materials, consisting 19 hybrids, their parents and F₂ bulks was studied. Only four hybrids expressed significant heterosis over mid-parent; and of these, two were found to be significantly superior to their respective better parent also. The hybrid between ICPA 2209 and ICPL 20108 was the best with respect to heterobeltiosis (55.9%**) and relative heterosis (60.5%**). The studies also showed that both additive as well as non-additive genetic variation played a key role in the manifestation of hybrid vigour. Based on the molecular diversity of the parents, two heterotic groups were formed in A-lines, while three heterotic groups were formed in the R-lines. The results showed that in this material high heterosis was not necessarily related to their molecular diversity.