Effects of Atmospheric Humidity on Abscisic Acid Accumulation and Water Status in Leaves of Rice (Oryza sativa L.)

Rice (Oryza sativa L ) plants were grown in controlled environment cabinets with either low (c 0 4 kPa) or high (c 1 6 kPa) atmospheric water vapour pressure deficit (v p d) The capacity of detached leaves to accumulate ABA in response to rapidly induced water stress was increased when plants were grown at high v p d High v p d significantly lowered solute potential (ψ2) without reducing total water potential (ψ) Hence, plants grown at high v p d had a higher leaf turgor potential (ψp) The treatment employed to induce ABA accumulation (a 10 per cent reduction in fresh weight), reduced ψp to zero in all leaves Hence, the total change in ψp (Δψp) was greater for leaves grown at high v p d Short-term (24–48 h) exposure to changed v p d was shown to be effective in altering both leaf water status and subsequent ABA accumulation Correlations between ABA accumulation and Δψp were demonstrated Links between humidity, transpiration flux, leaf water status and water stress-induced ABA accumulation, are described and discussed