Gibberellic acid application for hybrid rice seed production under wet and dry seasons.

摘要

The effects of gibberellic acid (GA; 0, 30, 45, 60 or 90 kg/ha) on hybrid rice seed production using IR58025A and IR34686R as female and male parents, respectively, were studied. GA was applied when 10-15% of the plants had started heading (40% of the total rate) and at one day thereafter (60%). Spraying of 80, 110 and 130 g GA/ha during the wet season resulted in panicle exertion rates of 52.14, 52.32 and 57.44%, respectively. During the dry season, the highest percentage of panicle exertion (71.35%) was obtained with 110 g GA/ha. During the wet season, the highest number of filled grains per panicle (21.62) was recorded for 130 g GA/ha. During the dry season, 80 g GA/ha gave the highest number of filled grains per panicle (70.65). GA had no significant effects on 1000-grain weight in the female parent during both planting seasons. However, 1000-grain weight was higher during the dry season (19.60 vs. 17.44 g). The highest seed yields were obtained with 130 g GA/ha during the wet season (83.87 kg/ha) and with 80 g GA/ha during the dry season (1919.83 kg/ha). The results indicated that GA at 80 kg/ha is optimum for hybrid rice seed production..