Leaf sucrose and starch contents and osmotic adjustment in two tomato cultivars under water deficit

Abstract

Leaf sucrose and starch content responses to water deficit in Pera Quibor (PQ) and Rio Grande (RG) tomato cultivars were compared. Soil water potential decreased under water deficit. Leaf water (?w) and osmotic potentials (?s) and relative water content (RWC) decreased in both cultivars under water deficit. Clear differences between the ?s values of control and water deficit plants in both cultivars were observed. Sucrose content increased with water deficit. The starch content showed decreases in both cultivars in control and treated plants during the studied period. This decrease was higher in control than in treated plants. In cv. PQ, starch content increased in control plants at the end of the water deficit period (wdp). The results showed that calculated osmotic adjustments were identified in the studied cultivars, and it could be attributed to the gradual decrease observed in the water status parameters during the wdp. Such a gradual slow-down may be the clue for osmotic adjustment as a mechanism in drought-tolerant cultivars, and it may also be interpreted as well, as an important attribute of drought-resistance in tomato.