HETEROSIS AND COMBINING ABILITY AMONG AFRICAN PEARL-MILLET LANDRACES

Breeding procedures used in pearl millet [Pennisetum glaucum (L.) R. Br.] improvement in India and the USA are aimed at exploitation of hybrid vigor for both grain and forage yields. Selection efforts in Africa have been limited to intrapopulation improvement for grain yield. Knowledge of heterotic patterns and combining ability of the widely cultivated African landraces would be useful in the development of a sound breeding program in Africa. The objectives of this study were to evaluate the combining ability and heterosis among African pearl millet populations and to explore the utility of interpopulation improvement for the development of high yielding varieties and hybrids. Five populations and their 10 interpopulation crosses were evaluated in a randomized complete-block design with six replications at two locations in Niger during the 1989 and 1990 rainy seasons. Plant height, flowering time, natural incidence of downy mildew, spike length, grain yield, and 1000-seed weight were measured in different populations. Significant differences among entries for most of the traits were observed. Better-parent heterosis for grain yield ranged from 25 (Iniari x Ugandi) to 81% (Mansori x Ex-Bornu). Six of the crosses showed significant heterosis and gave 36 to 81% more grain yield than their better parent. All crosses except one were significantly more tolerant to downy mildew than their better parent. Mean squares for general combining ability were significant (P < 0.05) for most traits indicating the importance of additive gene effects for these traits. The large heterotic effects and the magnitude of the additive effects observed in the experiment should be useful in choosing pearl millet landraces for intercrossing in the development of cultivars with improved grain yield.