Summary

Tomato plants (Lycopersicon esculentum Mill. cv. Early Girl) were grown in a medium containing peat moss and perlite (60:40% by volume). The medium was drenched with 0 or 5% of antitranspirant GLK-8924. Half of the plants were flushed daily with 250 ml water (leaching) and the other half were subirrigated by capillarity. The osmotic potential of medium solution was reduced significantly by 5% antitranspirant GLK-8924 treatment, then recovered gradually to the control level after 4 d with leaching and 10 d without leaching. Leaf stomatal conductance (g_s), transpiration rate (E) and plant growth were depressed by the antitranspirant GLK-8924 application, and the depression was alleviated by leaching. Neither antitranspirant GLK-8924 treatment nor leaching influenced leaf abscisic acid (ABA) content. The effect of antitranspirant GLK-8924 on leaf gas exchange and plant growth was highly correlated with the reduction in the osmotic potential of medium solution but not with leaf ABA content. Younger leaves had higher g_s and E but lower ABA content than older leaves in general.