Natural cross-pollination is both a boon and bane for pigeonpea breeders

Abstract

Natural cross-pollination in pigeonpea, mediated by insects, is a universal phenomenon with the first report appearing in 1919. Considerable information is now available on various aspects of this biological phenomenon including degree of out-crossing and pollinating agents in different parts of the world. A large variation (0-60%) has been recorded in 30 different environments across 11 countries. The role of cross-pollination in rapid deterioration of the genetic purity of cultivars and elite genetic stocks is well understood and documented by breeders and seed producers. Pigeonpea breeders have converted this constraint into an opportunity by way of visually selecting natural hybrids from landraces in farmers’ fields and deriving high yielding cultivars. In a key development, the occurrence of natural cross-pollination in the wild relatives of pigeonpea has also been recorded; and in three wild species such natural hybrids have yielded valuable cytoplasmic male sterility systems. This has encouraged breeders to develop a hybrid breeding technology with natural out-crossing playing a key role in the large-scale seed production of commercial pigeonpea hybrids.