Abstract
To make clear the action of ethylene in the growth of rice seedlings, three experiments were carried out as follows. First, growth of coleoptiles and seminal-roots of different types of rice varieties were tested. Second, the interaction of ethylene and ABA in the growth of rice seedlings were tested. Finaly, the ethylene evolution from soaked seeds was actually measured and its effects on the growth of rice seedlings under different seedlng density was examined. The results obtained were as follows. 1. Elongation of coleoptiles was promoted whereas the growth of seminal-roots was inhibited with ethylene treatment. 2. Diffefent varieties were found to respond differently to the ethylene treatment; coleoptiles of Japonica varieties and seminal-roots of indica varieties were more sensitive than the others. 3. Elongation of the coleoptiles was promoted by 10 ppm of ethylene combined with 1 ppm of ABA. 4. Interaction of ethylene with ABA in the elongation of mesocotyls was also recognlzed . 5. Ethylene concentration was increased in high seeding density and it promoted the elongatlon of coleoptiles.
