Abscisic Acid Accumulation in Detached Leaves of Rice (Oryza sativa L.) in Response to Water Stress: A Correlation with Leaf Size

When water stress was imposed on detached leaves of two rice(Oryza sativa L.) cultivars, more ABA per unit fresh weightaccumulated in IR20, a small-leaved cultivar, than in 63–83,a large-leaved cultivar; the difference being up to threefold.In an F₂ population of a cross between the two cultivars ABAaccumulation was found to be significantly negatively correlatedwith leaf fresh weight. This correlation persisted in the F₃generation. Such a correlation was not evident, however, whena number of rice cultivars, which varied widely in leaf size,were examined. The difference in ABA accumulation between IR20 and 63–83was not accounted for by different spatial patterns of waterloss or ABA accumulation within a leaf, and cultivar differencesin ABA content were maintained both across, and at various positionsalong the leaf. No major differences in leaf anatomy were observed between thetwo cultivars. Differences found in leaf water relations characteristicswere few and generally minor. It therefore seems unlikely thatthese properties account for the difference between the cultivarsin the ability to accumulate ABA or for the correlation withleaf size. Oryza sativa L, rice, water stress, abscisic acid, leaf size