EFFECTS OF SHORT-TERM WATER-STRESS, HYDROPHILIC POLYMER AMENDMENT, AND ANTITRANSPIRANT ON STOMATAL STATUS, TRANSPIRATION, WATER-LOSS, AND GROWTH IN BETTER BOY TOMATO PLANTS

Seedling plugs of 'Better Boy' tomato plants (Lycopersicon esculentum Mill,) were potted in 60% processed fiber: 40% perlite (by volume) med ia amended or nonamended with either crystalline or powdered hydrophil ic polymer (2.4 kg . m(-3)), and treated with one of several concentra tions (0%, 2.5%, 5%, 7.5%, and 10%) of antitranspirant GLK-8994, at th e four true-leaf stage, Plants were either wed-irrigated or subjected to short-term water stress, withholding water for 3 days, after antitr anspirant GLK-8924 application, Leaf stomatal conductance, transpirati on rate, whole-plant transpirational water loss, and growth were depre ssed by short-term water stress and antitranspirant GLK-8924, In contr ast, hydrophilic polymer amendment increased plant growth, resulting i n higher transpirational water loss, The depression of stomatal conduc tance and transpiration rate by short-term water stress was reversed c ompletely in 2 days after rewatering while the reduction of plant grow th rate diminished immediately, The effects of antitranspirant GLK-892 4 were nearly proportional to its concentration and lasted 8 days on s tomatal conductance and transpiration rate, 4 days on plant growth rat e, and throughout the experimental period on plant height and transpir ational water loss, Plant growth was reduced by antitranspirant GLK-89 24 possibly by closing leaf stomata, In contrast, hydrophilic polymer amendment resulted in larger plants by factors other than influences a ttributed to stomatal status, Hydrophilic polymer amendment did not in teract with antitranspirant GLK-8924 on all variables measured, The ap plication of antitranspirant GLK-8924 was demonstrated to be useful fo r regulating plant water status, plant growth, and protecting plants f rom short-term water stress.