The effect of gibberellic acid on male fertility in bread wheat

The effect of gibberellic acid (GA sub(3)) on male fertility was investigated in wheat. Greenhouse and field experiments were carried out. GA sub(3) induced high levels of male sterility both in gibberellin (GA)-sensitive and GA-insensitive genotypes. The optimum concentration was 2000 ppm of GA sub(3) when applied at successive sprays. The critical period for GA sub(3) treatment, in the general sense, extended from glume differentiation to premeiotic interphase in the oldest florets of the spike, though differences were found between GA-sensitive and GA-insensitive genotypes in the extension of this period. The effect of GA sub(3) on plant height was also studied. The potential use of GA sub(3) as a chemical hybridizing agent in wheat breeding is discussed.