Assessment of salinity tolerance threshold for two wheat genotypes in response to zinc

Plants' tolerance to salt stress is different among species, nevertheless, mineral nutrition might also affect it. A greenhouse experiment was conducted to evaluate the effect of Zinc (Zn) on salinity tolerance using a sigmoid response model in two wheat (Triticum aestivum L.) genotypes Falat' and Bam' with different salinity tolerances. The treatments consisted of three Zn rates (0, 5 and 10mgZnkg(-1)) and five levels of soil salinity (1.1, 6.5, 12.3, 18.7 and 25.1dSm(-1)). The results showed that dry weight of straw and grain decreased, as salinity increased in both genotypes although this decrease in Falat' genotype was higher than that of Bam' genotype. Application of 10mgkg(-1) Zn increased the dry weight by 25% (straw) and 32% (grain) in Falat' but 67% (straw) and 60% (grain) in Bam' as compared with the absence of added Zn. According to the fitted function, in the absence of Zn, grain production began to decline at ECe-values of 4.7dSm(-1) in Falat' genotype, and 7.5dSm(-1) in Bam' genotype. Application of Zn led to a decrease of salinity tolerance in Falat' genotype, but an increase in Bam' genotype. The study found that Zn application under saline conditions, depending on genetic differences of wheat genotypes, would have different effects on their tolerance to salinity.