Effect of Transpiration-reducing Chemicals on Growth, Flowering, and Stomatal Opening of Tomato Plants

Abstract

(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...

Effects of Cycocel and Irrigation Regimes on Some Physiological Parameters of Three Olive Cultivars

“…The results of this study are similar to others (Fernandez et al, 1994;Giorio et al, 1999). Similar trends were also reported for other plants such as banana (Ismail et al, 2004), tomato (Mishra and Pradhan, 1972;Malash and Flowers, 1984), rice and eggplant (Prakash and Ramachandran, 2000;Halder and Burrage, 2003). Mishra and Pradhan (1972) and Malash and Flowers (1984) reported a decline of the dry weight of treated seeding of tomatoes following Cycocel application.…”

“…Similar trends were also reported for other plants such as banana (Ismail et al, 2004), tomato (Mishra and Pradhan, 1972;Malash and Flowers, 1984), rice and eggplant (Prakash and Ramachandran, 2000;Halder and Burrage, 2003). Mishra and Pradhan (1972) and Malash and Flowers (1984) reported a decline of the dry weight of treated seeding of tomatoes following Cycocel application. Cycocel, by further closing of stomata and reducing of diffusion of carbon dioxide into leaf cells, causes reduction of both photosynthesis and total dry weight.…”

“…It is likely that the Cycocel application can affect the internal metabolisms of stomata cells. The more closing of stomata, recovers the efficiency of plant water usage until plant reduces transpiration, without any negative effects on stress tolerance (Mishra and Pradhan, 1972;Malash and Flowers, 1984;Giorio et al, 1999). Duration of stability of effect of Cycocel on stomata in this research was clear until the end of 4 weeks, so that until the end of experiment, stomata conductive of plants treated by Cycocel remained on a lower level compared to control plants.…”

“…The main change is the stomata closure in order to reduce transpiration rate and prevent water loss (Saei et al, 2006). Cycocel induced stomata closure and delayed wilting and the effect stabled about one week (Mishra and Pradhan, 1972;Malash and Flowers, 1984). Skene and Mullins (1967) showed that Cycocel reduced the number of stomata in dry farming-corn and in contrast the percentage of closed stomata increased.…”

“…Skene and Mullins (1967) found roots of Vitis vinifera L. plants grown in solution cultures containing Cycocel were shorter and thicker than those of untreated control plants. Mishra and Pradhan (1972) and Malash and Flowers (1984) reported that Cycocel reduced shoot growth and hence the overall dry weight of plant and reducing the ratio of dry weight of shoot to root. Skene and Mullins (1967) found that the CCC had markedly affected on the appearance of the roots.…”