Exploiting heterosis in pearl millet for population breeding in arid environments

In the desert region of Rajasthan, India, farmers mainly grow pearl millet [Pennisetum glaucum (L.) R. Br.] landraces. The adoption of modern cultivars is generally low because of their poor adaptation to extreme drought stress. The objective of this study was to evaluate the performance of six elite breeding populations and three landraces and to determine the heterotic pattern among the 36 diallel crosses of those populations. Field experiments were conducted in eight environments in India. Mean grain yields (GYs) in the three environments with favorable growing conditions were double to threefold those in the three arid environments. The elite populations generally showed higher GY than the landraces; stover yield (SY) was similar in both population types. The landraces flowered earlier, had a higher tillering potential, and smaller seeds. Mean level of midparent heterosis was generally low, ranging from 0.85% for time to flowering (TF) to 6.57% for SY. For GY, expression of heterosis for individual population crosses was between -14 and +30% under drought stress, and between -9 and +17% in the favorable environments. For SY, mean heterosis was always positive and higher than for GY. The elite x landrace population crosses with high mean GY and high levels of heterosis under drought stress could be beneficial to widen the germplasm base and to combine the high yield potential of elite materials with the good adaptation of the landraces