Effects of seed-soaked GA3 and inorganic salts on mesocotyl and coleoptile elongation in rice.

摘要

The elongation of mesocotyl and coleoptile is important in seedling emergence and stand establishment of dry direct-seeded rice. Experiments were carried out to elucidate the effects of seed soaking in GA3 and some inorganic salts on the mesocotyl and coleoptile elongation of rice. Seed treatment with GA3 promoted the elongation of mesocotyl, but had little effect on the coleoptile elongation. The stimulation by GA3 was enhanced by addition of CaCl2, although CaCl2 alone did not stimulate mesocotyland coleoptile elongation. Mesocotyl elongation was most prominent from combined treatment with 50 ppm GA3 and 100 mM CaCl2. The synergistic effects of GA3 and CaCl2 on mesocotyl elongation varied with cultivar type. The stimulating effects of GA3 wereenhanced significantly by the addition of CaCl2 in japonica cv. Dongjinbyeo, Ilpumbyeo and Milyang 95, and tall indica cv. Labelle, but not in semidwarf Tongil type cv. Tongilbyeo, Milyang 23 and Nampungbyeo, or semidwarf indica cv. Short Labelle. The promoting effects of GA3 on mesocotyl elongation were decreased by lowered osmotic potential from PEG 6000. This suggests that the synergistic effects of CaCl2 with GA3 on mesocotyl elongation were not caused by the lowering of osmotic potential by CaCl2,but by the salt itself. Salts such as Ca(NO3)2, MgCl2, BaCl2, NaCl, KCl and KNO3 also had synergistic effects with GA3 on mesocotyl elongation, with no significant differences between salts.