INFLUENCE OF A1 CYTOPLASMIC SUBSTITUTION ON THE DOWNY-MILDEW INCIDENCE OF PEARL-MILLET

Large-scale cultivation of pearl millet [Pennisetum glaucum (L.) R. Br .) F1 hybrids in India has led to increased incidence of downy-mildew (Sclerospora graminicola). There is concern that the A1 male-sterile c ytoplasm used in all the hybrids released so far is responsible for th is increase. The influence of A1 male-sterile cytoplasm on downy-milde w incidence in pearl millet was studied by comparing the disease react ion of 40 pairs of F1 hybrids, each pair carrying respectively A1 male -sterile and normal B cytoplasm. Mean downy-mildew incidence was simil ar in the hybrids carrying either A1 male-sterile or B cytoplasm. The general combining ability of lines with and without A1 cytoplasm was f ound to be similar for downy-mildew incidence. These results indicated that in pearl millet A1 cytoplasm is not associated with increased do wny-mildew incidence. The possible danger of using only one source of cytoplasm has been briefly discussed.