(3,12,14,19,20) and the metal chelate 20). Certain growth retardants such as CCC and B-Nine belong to the latter group (2,5,13). A comprehensive review of the physiology of growth-retarding chemicals has also appeared (2). It seems well established that transpiration can be reduced by foliar application of PMA (3,10,(14)(15)(16)19),, CCC (1, 2, 10) and B-Nine (10, 13). Yet the physiological effects of spray application of these chemicals have not yet been adequately studied.The water status of the plant is determined both by the soil moisture conditions and by the evaporative demand of the atmosphere. It is suggested (4) and stomata are closed, transpiration suppressants will be less effective. PMA is very effective under conditions of low soil moisture stress (3), i.e., in wet soil.The purpose of this investigation was to evaluate the growth, flowering, yield, and stomatal responses of transpiration suppressant-treated and untreated tomato plants grown in wet soil. It is our opinion that as growth is controlled by water deficits in the plant, a comparison between treatments after inducing water deficit by increasing soil moisture stress would be misleading. Hence care was taken to minimize the effect of soil moisture tension during the experimental period. The effect of these chemicals in reducing the transpiration of tomato plants has been reported (10).
MATERIALS AND METHODS
Plant Material. Seeds of tomato (Lycopersicon esculentumtzMill. cv. Sioux) were sown in a nursery bed. Healthy and uniform (about 11 cm in height) 21-day-old seedlings were transplanted to 30-cm earthenware pots containing approximately 30 kg of garden soil and manure (3:1). The soil was sandy loam and contained 0.28 to 0.38 g of water per g dry soil following irrigation. There were two plants per pot and five pots per treatment. As far as practicable care was taken to maintain uniformity in initial plant size, soil weight, and atmospheric humidity for the plants of the control and treated series.Irrigation Procedure. Plants were watered daily during the entire growth measuring period. Fifty-nine days after the seventh spray application, fruit was harvested and irrigation was withheld. At this stage the plants were 138 days old, and the soil water content was about 33%. Soil water stress was induced at this stage because six harvests had already been collected and stress induced at this stage would reveal the responses of treated plants to soil drought without affecting measured plant growth and yield.Spray Treatments. The first foliar spray was given to the 37-day-old plants with the different test solutions, i.e., CCC (5 mM), B-Nine (5 mM), PMA (0.1 mM), and 8-HQ (1 mM). Spraying was repeated at weekly intervals and the plants received seven spray applications during the experimental period. Teepol (British Drug House) was used with the spray solution as the wetting agent. Distilled water containing Teepol was sprayed on the control plants. The spray was applied to the plants in the afternoon until the plants were dripping wet. Each p...
