Stomatal changes following abscisic acid treatment in several broad-leaved trees undergoing artificial shade treatment

Changes in the resistance of stomatal transpiration following abscisic acid (ABA) treatment were investigated in four species of broad-leaved trees that underwent artificial shade treatment. In all four species, Betula platyphylla, Betula schmidtii, Zelkova serrata and Acer mono, the light environment exerted a significant influence on the differences of stomatal transpiration and its changes. The time series changes among the four tree species showed varied tendencies according to the type of treatment and level. In the case of Acer mono, Betula platyphylla and Betula schmidtii, transpiration resistance increased following ABA solution treatment at a low concentration of 0.02 mmol. In addition, the differences were increased according to artificial shade treatment levels and with the passage of time. In the case of Zelkova serrata following ABA treatment at a concentration of 0.05 mmol, seedlings which were developed in a high shade treatment with a back-light rate of 6% showed a high transpiration resistance of 61.36 s^-1/cm at 2 hours after treatment, and it increased greatly with increasing shade intensity and treatment concentration. ABA absorption treatment of the branches indicated the strong effect of shade intensity on stomatal diffusive resistance after processing in an artificial light environment. Therefore, we considered that ABA did not affect the physiological characteristics of the tree species but that the damage was caused by the light environment at the time of measurement. We also determined that light was a factor that had some effect on the increase of transpiration resistance through stomatal closure in the case of the seedlings developed in different light environments.