Modification of Leaf Size in Rice (Oryza sativa L.) and its Effects on Water Stress-induced Abscisic Acid Accumulation

Abstract

The ability of detached leaves of the rice cultivars IR20 and 63–83 and their F2 progeny to accumulate ABA in response to water stress is negatively correlated with leaf size. It was shown that this association was not an artifact of incubation conditions following the imposition of stress. Also, it was possible to break the correlation by selecting plants in segregating populations which differed in ABA yet had similar leaf size. In further experiments, leaf size was altered phenotypically by various treatments; either being increased by gibberellin application or periodic removal of tillers, or reduced by prior exposure to water stress or ABA. Although responses to these treatments were complex, the results demonstrated that leaf size and accumulation capacity were at least partially independent. It is suggested that the correlations observed previously in F2 populations from the cross IR20 × 63–83 were a result of genetic linkage.