Abstract:
A solution culture experiment was conducted to evaluate the salinity tolerance of 15
tomato genotypes in Hoagland’s nutrient solution with three levels of NaCl (0, 75, and 150
mM). The experiment was conducted in completely randomized design with three
replicates. After 30 days of imposition of salt stress, gas exchange parameters including
transpiration rate, stomatal conductance, CO2
assimilation rate, and intercellular CO2
concentration were recorded and the harvested plants were characterized for growth
(shoot/ longest root lengths and fresh/dry weights) and ionic characteristics (Na+
, K+ and
K
+
/Na+ ratio) parameters. All growth and gas exchange parameters decreased with
increasing NaCl concentrations. However, this decrease was less in salt-tolerant genotypes
as compared to salt-sensitive genotypes. It was also observed that with the increasing
NaCl concentration in the rooting medium, the amount of Na+
in the plant tissues
increased while the amount of K+ ion decreased. Thus, it was concluded that the plants
with more K+
absorbing ability, with high K+
/Na+
ratio, and higher growth were more
salt-tolerant. Also, the results showed that fresh and dry weights, gas exchange
characteristics, and K+
/Na+
ratio were very effective in determining salt tolerance of
tomato. Considering the genotypes, Indent-1 and Nagina were characterized as salt
tolerant and the Red Ball and Peto-86 as salt sensitive under saline conditions.
Keywords: Salinity tolerance, K+
/Na+
, Photosynthesis, Growth
