IMPROVEMENT OF LANDRACE CULTIVARS OF PEARL-MILLET FOR ARID AND SEMIARID ENVIRONMENTS

Successful cultivars for arid and semi-arid environments must combine adaptation to drought stress for dry years with a reasonable yield pot ential for better years. Improving the yield potential of adapted land race cultivars may be the easiest way to achieve this combination for breeding programs with limited resources. This study, conducted with f our adapted pearl millet landrace cultivars, compared the yield improv ement from one cycle of S-1 progeny plus mass reselection with that fr om topcrossing the landraces on an early male-sterile line, with a goo d combining ability for grain yield. A single cycle of reselection inc reased mean yield of the landraces by 11% over seven test environments , ranging in yield from 470 to 3010 kg ha(-1). Topcrossing raised yiel ds by an average of 32% over the same test environments. Topcrossing i ncreased responsiveness to improved environmental resources, as the ad vantage of the topcross hybrids over their parent landraces increased as environmental mean yield increased. Reselection, in contrast, incre ased mean yield but did not improve the response of the reselected cul tivars to a changing environmental yield level.