Abscisic Acid and Water Relations of Rice (Oryza sativa L.): Effects of Drought Conditioning on Abscisic Acid Accumulation in the Leaf and Stomatal Response

Publisher Website
Google Scholar
Abstract
The effects of a period of water stress (drought conditioning) on responses to a second (challenge) stress were examined in young vegetative rice (Oryza sativa L.) plants. Drought conditioning did not affect the rate of subsequent stress development, nor, in a first experiment, did it influence relations between turgor (ψp) and total (ψ) leaf water potential. However, conditioning did extend the range of ψp over which stomata remained open and significantly reduced the amount of ABA which accumulated in the leaf at a given ψp. The change in stomatal behaviour (stomatal adjustment) was quantitatively accounted for by the change in leaf ABA accumulation. The reduction in ABA accumulation due to conditioning did not involve a change in the potential capacity to produce ABA, as ABA accumulation in partially dehydrated detached leaves was not reduced by conditioning. It is suggested that effects of conditioning on leaf ABA content in the intact plant involve changes in the rate of ABA export from the leaf.