INFLUENCE OF WATER-STRESS ON ABSCISIC-ACID AND ETHYLENE PRODUCTION IN TOMATO UNDER DIFFERENT PAR LEVELS

Tomato plants (Lycopersicon esculentum Mill cv. Better Boy) were grown in plastic pots under greenhouse conditions. The plants were subjected to 0.07 MPa (high) 0.015 MPa (medium) and 0.001 MPa (apparent saturation moisture stress conditions), and exposed to high (1200), medium (900.) and low (600) mumol m-2 s-1 photosynthetically active radiation (PAR) supplied by Metalarc lamps (500-620 nm). Soil moisture and light levels induced different effects on tomato plants. Low stress and apparent soil moisture saturation regimes increased ABA and ethylene concentrations, and reduced nonstructural carbohydrate and total chlorophyll content. Moisture stress influenced the above variates more than PAR levels.