Gibberellic Acid與Abscisic Acid對矮生稻幼苗生長的影響

Abstract

GA3 enhances the elongation growth of early dwarf rice (Oryzae sntiva cv, I-Geo-Gen) seedlings. Markedly preceding growth of the shoots is an increased RNA synthesis, as shown by total RNA determination and 32P-incorporation into RNA. But the increase in DNA content is later and is evident after treatment with GA3 for 4 days. ABA inhibits shoot elongations, nucleic acid and protein synthesis. When GA3 is added together with ABA, it is found: 1) the inhibition of shoot growth by higher concentration of ABA (above 5 x 10^(-5) M) can't be overcome by the additton of GA3 even at reasonably high concentration. 2) the inhibition of growth by ABA below the concentration of 5 x 10^(-5) M can be gradually overcome by increasing the cone, of GA3. When ABA (5 x 10^(-6)M) is added together with 5 x 10^(-4) M GA3 for 5 days, shoot length of the dwarf rice seedlings reaches the level of dist, water control. RNA content is largely reversed, but the content of DNA, protein and shoot dry weight, though increased slightly, are still markedly inhibited over 50%. These results suggest that the interaction between GA3 and ABA is partial, incomplete and non-competitive, i. e., GA3 can only overcome part of the inhibitory action of ABA, while the other part, maybe the most part, on which they both act differently and independently can't be overcome by the addition of axogenous GA3. In addition, the interaction between these 2 hormones in the control of seed germination, α-amylase synthesis in embryoless half endosperms, and root growth o f seedlings are studied and discussed.