Screening Some Tomato Commercial Cultivars from Thailand for Salinity Tolerance

Hydroponically-grown seedlings of thirteen commercial tomato cultivars and breeding lines were exposed to 0 (control) and 200 mM NaCl (salt stress) for ten days. Salt tolerance was evaluated based on visual appearance of plant damage and the plants were assigned the scale from 1 (most tolerant) to 4 (most sensitive). The salinity scales ranged from 1.00-3.75. All genotypes responded to salt by an accumulation of Na+, reduction in K+, Ca2+, N and shoot/root dried weight and a small increase in P. Salinity tolerance scales, ion concentration and shoot/root dried weight differed greatly among tomato genotypes. Highest correlation was found between salinity tolerance scale classes and the reduction in root dried weight, followed by the reduction in shoot dried weight, Na+ concentration, Ca2+ /Na+ and K+/Na+ ratios. The amount of N and P content did not correlate with salinity scale classes. In general, Na+ concentration and the reduction in root/shoot dried weight were the most reliable parameters useful for screening salt tolerance of tomato at the vegetative stage.