PERFORMANCE AND STABILITY OF PEARL-MILLET TOPCROSS HYBRIDS AND THEIR VARIETY POLLINATORS

A majority of farmers in the arid and semiarid regions of Africa and South Asia continue to cultivate their local landraces of pearl millet [Pennisetum glaucum (L.) R. Br.], rather than improved varieties. The reasons for this preference for local landraces may include their better yield stability and adaptation to environmental stress, although their grain yield potential is often lower than that of the new varieties. This study was conducted to test the hypothesis that the yield potential of such landraces could be improved without seriously affecting their stability and adaptability, by using them as pollinators in topcross hybrids. Three pollinator groups (five accessions per group) reflecting three levels of breeding effort were crossed on two male-sterile lines selected to specifically advance time to flowering and to increase individual grain mass. Topcrosses and their pollinators were evaluated in India, during the rainy season at three locations (ICRISAT Center, 17.50-degrees-N, 78.47-degrees-E; Anantapur, 14.68-degrees-N, 77.62-degrees-E; Fatehpur, 27.17-degrees-N, 75.13-degrees-E) in 1988 and 1989 and at Hisar (29.15-degrees-N, 75.73-degrees-E) in 1989, and during the dry season in irrigated and stress conditions at ICRISAT also in 1988 and 1989. Mean grain yields ranged from 66 to 477 g m-2. The adaptability, stability, and responsiveness of the topcrosses and their pollinators were compared using joint regression analysis. Analyses of adaptability, based on the predicted grain yield of topcrosses and their pollinators in two low yielding environments, indicated that the topcrosses were either equal or superior to their pollinators. Analysis of stability based on the deviations from regression indicated that the topcrosses were either as stable, or more so than their pollinators. Analyses of responsiveness, as measured by the regression coefficient, indicated that the topcrosses were more responsive to improved environmental conditions than their pollinators. The results suggest that rapid improvement in adapted landraces is possible through their use as topcross hybrids in pearl millet.