Relationship between Some Physiological Characters and Yield of Heat-Toler-ant, Non-Tolerant, and Tropical Tomato Cultivars Grown at High Temperature

Abstract

The relationships between physiological characters; photosynthesis (P_r), transpiration (E), stomatal conductance (G_s), and yield of three heat-tolerant tomato (Lycopersicon esculentuin Mill.) cvs. Shikiaka, Shuki and Ohio 7663, non heat-tolerant cv. Sataan; and two tropical cvs. Owusu-Bioh and Wosowoso, grown at 40°/23°C day/night temperatures were examined.
Physiological characters were measured at air temperatures of 20°, 30°, and 40°C. P_r for heat-tolerant cultivars pooled at the seedling stage (57 leaves) was significantly greater than non heat-tolerant cultivars at 20° and 40°C. P_r, E, and G_s, at the flowering and early fruit development stage (1315 leaves) were significantly higher in the heat-tolerant cultivars compared to the other cultivars at all temperatures. P_r at the seedling stage did not significantly correlate with yield but P_r, E and G_s were significantly correlated with fruit yield at the flowering and early fruit development stage. A linear relationship between P_r and G_s and between E and G_s revealed a close and significant consequential relationship between E and P_r. Regressions among physiological variables were not homogenous among/between cultivars. Regressions between P_r, E, G_s, and yield were heterogenous among/between cultivars. Heat-tolerant cultivars had greater yields than the other cultivars. The results indicate that yield significantly and positively correlated with P_r, E. and G_s.