Abstract
We investigated the relationship between the forms of emergence and the seedling growth of rice(Oryza sativa L.)and the effects of plant growth regulators on the forms of emergence and seedling growth. In the first experiment, two cultivars of M type(Tchampa, Hei Chiao Chui Li Hsiang Keng)and two of S type(Haginomae Mochi, Shan Kiu Ju)were used as materials according to the results of the previous experiments. All cultivars were sown at a depth of 5.5cm. The mesocotyl growth was promoted in the case of M type, whereas the elongation growth of coleptile and the first leaf were inhibited when compared with S type. The growth of mesocotylar toots was also stimulated. The emergence rate of cultivars of S type was smaller than that of M type, but the growth after emergence was faster. The leaf number of seedlings of S type was greater than that of M type at 15 days after seeding. In the second experiment, we studied regulation of the forms of emergence and seedling growth by using five plant growth regulators, including three plant hormones, ABA, GA3 and ET, and two inhibitors of gibberellin biosynthesis, BX-112 and PP-333. The sowing depth was 5.5cm. As a result, in S type or F type cultivar, the form of emergence was changed to M type by an application of ABA. In F type, the form of emergence changed to S type by BX-112 or PP-333 application. These results suggest that the form of emergence is determined by plant hormones.
