SMUT REACTION OF PEARL-MILLET HYBRIDS AFFECTED BY FERTILITY RESTORATION AND GENETIC-RESISTANCE OF PARENTAL LINES

Pearl millet (Pennisetum glaucum (L.) R. Pr) hybrids based on the Al c ytoplasmic-nuclear male-sterile (CMS) lines are more susceptible to sm ut (Tolyposporium penicillariae Bref.) than open-pollinated varieties. Seventy eight pairs of hybrids, made onto male-sterile (A) lines and their counterpart maintainer (B) lines, were evaluated to examine the effects of male sterility and genetic resistance of parental lines on the smut severity of hybrids. The A-line hybrids had higher smut sever ity and lower selfed seedset than the counterpart B-line hybrids, indi cating that it is the CMS-mediated male sterility rather than the Al c ytoplasm per se that caused greater smut severity of A-line hybrids. H owever, with the use of resistant parental lines even male-sterile hyb rids of A-lines, in several cases, were as resistant as some of the hi ghly resistant male-fertile hybrids of B-lines. It would be possible t o produce smut resistant hybrids (< 10% severity) on A-lines, albeit i n low frequency, even if only one parent of a hybrid were resistant. H owever, the probability of producing such hybrids would be higher when both parents were resistant to smut. Thus, improvement in smut resist ance of parental lines and fertility restoration ability of pollinator s would provide the most effective genetic approach to smut disease ma nagement in hybrids.