Hybrid seed production in safflower (Carthamus tinctorius) following the induction of male sterility by gibberellic acid

The objective of the present research was to develop an effective and practical method for hybrid seed production in safflower, by inducing male sterility with gibberellic acid (GA 3 ). Seeds of the spiny line ‘5‐154’ and the non‐spiny variety ‘Dincer 5‐118’ were sown in alternate rows and the plants of the non‐spiny female variety were exposed to various concentrations of GA 3 for male sterility induction. Three successive sprays (75, 82 and 89 days after sowing) of 100 p.p.m. of GA 3 to safflower buds of <0.5 cm diameter at a pre‐meiotic interphase stage resulted in reduced pollen viability from 81.6‐6.7% compared with the control. An average hybrid seed percentage of 80.7% (87.5% in the secondary heads), identified by the use of the spiny‐capitulum marker variety ‘5‐154′, was obtained. The GA 3 treatments did not significantly affect the production of viable achenes. The results showed that GA 3 could be successfully used as a chemical hybridizing agent in hybrid safflower production.