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

High ergot (Claviceps fusiformis Loveless) susceptibility of pearl mil let (Pennisetum glaucum (L.) R. Br.) hybrids has often been associated with the A(1) cytoplasm of male-sterile lines (A-lines). To understan d the underlying basis of this association and to examine the prospect s of breeding ergot-resistant hybrids, we evaluated 56 hybrids and the ir 15 parental lines for ergot reaction and selfed seedset for 2 years in disease nurseries at ICRISAT Asia Center. Hybrids were made by cro ssing seven pollen parents (2 susceptible and 5 resistant) onto two re sistant and two susceptible A-lines, and their four corresponding main tainer lines (B-lines). A-lines had no selfed seedset while B-lines ha d 32-75% selfed seedset. Hybrids of A-lines had significantly less sel fed seedset than the hybrids of the corresponding B-lines. The reduced seedset of A-lines and their hybrids, however, was not always accompa nied by significantly higher ergot susceptibility. Highly resistant hy brids were obtained where both A-lines and pollen parents were highly resistant, regardless of male fertility levels of the hybrids. Thus, a lthough the A(1) cytoplasm, by its reduction of male fertility, had a large and significant effect in increasing ergot severity of hybrids, the contribution of nuclear genetic factors of female parents was abou t 1.8 times larger than that of the cytoplasm.