INCREASING DROUGHT TOLERANCE OF TOMATO PLANTS BY GRAFTING

The experiment was conducted in 3 steps in a growth chamber by aerated nutrient solution culture. Drought stress was fixed as Ψs=-1.0 MPa; and reached gradually with PEG addition. In the first step 10 commercially available rootstock genotypes (‘Beaufort’, ‘Maxifort’, ‘Unifort’, ‘Yedi’, ‘Kemerit’, ‘King Kong’, ‘Spirit’, ‘Resistar’, ‘500292’ and ‘Toro’) and in the second step 12 indeterminate tomato cultivars from different types in respect to their fruit weights (Cherry (10-25 g): ‘Sweet 100’, ‘AG1015’, and ‘M25’; Cocktail (25-65 g): ‘AG1051’, ‘Elettro’, and ‘M28’; Mid-jumbo (100-140 g) ‘Filinta’, ‘Petrus’, and ‘Sırma’; Jumbo (over 180 g) ‘Alyans’, ‘Borneo’, and ‘Ceylin’) were tested. Selection was made by weighted ranking method. Four rootstock genotypes were selected as ‘Beaufort’, ‘Maxifort’, ‘Yedi’ and ‘Resistar’ of which resistance against drought stress decreased in order. Among the tested cultivars; ‘M28’, ‘Petrus’ and ‘Alyans’ were selected according to response to drought stress that ‘M28’ and ‘Alyans’ were determined as resistant and sensitive, respectively. On the other hand ‘Petrus’ gave intermediate values in this respect. In the third step, the selected tomato cultivars were grafted on the selected rootstocks, and themselves (self grafted). It was determined that grafting increased the drought tolerance of tomatoes depending on the genotype of the rootstock.