Comparative Studies on Growth and Development of Heat-Tolerant and Non Heat-Tolerant Tomato Plants Grown at Different Root-Zone Temperatures

Abstract

Comparative studies on growth and development of young heat-tolerant tomato (Lycopersicon esculentum Mill. cv. Shuki) and non heat-tolerant one (cv. Sataan) grown under four root-zone temperatures (RZT) were carried out. Growth rates were measured at RZT of 15°, 20°, 25°, and 30°C. Plants in study 1, were grown for 10 days (21 to 31 days after sowing) and in study 2, 21 days (21 to 42 days after sowing). Optimum growth in both cultivars occurred at 30°C in plants grown for 10 days and at 25°30°C in plants grown for 21 days. Cultivar 'Shuki' had greater shoot fresh and dry weight, greater root dry weight and greater leaf area than 'Sataan' at all RZT. Cultivar 'Shuki. had greater NAR compared to 'Sataan' at all RZT. Significant and possitive correlations existed among growth parameters at all RZT in both cultivars. Biomass or carbohydrate production between the two cultivars at the end of 21 days was significantly different at RZT of 20°C and 25°C. The results indicate that the heat-tolerant cultivar, 'Shuki', is a better biomass or carbohydrate producer than the non heat-tolerant cultivar, 'Sataan'.