Effects of different levels of iron in nutrient solution on the response of three sunflower genotypes to salinity

A greenhouse experiment, as hydroponic, was carried out in order to investigate the response of sunflower genotypes (Hison125, Iroflor and Bliezer) to different levels of salinity (0, 60 and 120 mM of NaCl) and Fe (0, 50 and 100 mM) in nutrient solution. The experiment was arranged as factorial, based on a completely randomized blocks design with four replications. Results showed that plant height, leaf area, shoot and root dry weight, ratio of shoot/root dry weight, K concentration, the ratio of K/Na concentration in shoot and roots were reduced and the concentration of Na was increased as the level of salinity was increased in the nutrient solution. There was a significant increase in the values of plant height, leaf area, shoot dry weight and the ratio of shoot/root dry weight as the level of Fe in the nutrient solution was enhanced from 5 to 50 mM. However, with a further increase from 50 to 100 mM, there appeared no significant changes in the amount of these traits. The interaction between genotype and Fe level was significant on the root dry weight and K concentration in the leaves. The lowest and the highest increase in root dry weight, in response to increased level of Fe, was observed in Hison125 and Bliezer cultivars, respectively. However, the difference between cultivars became less in treatments containing higher levels of Fe in the nutrient solution. Considering the K concentration in leaves, only Bliezer cultivar showed positive response to increasing Fe level. The interaction between salinity, genotype and Fe level was significant on the concentration of Fe in plant. Based on the results, increasing Fe concentration in the nutrient solution improves sunflower growth. However, the increased concentration of Fe could not significantly alleviate the negative effects of salinity.