The Effects of Humic Acid and Calcium on MorphoPhysiological Traits and Mineral Nutrient Uptake of Pistachio Seedling under Salinity Stress

The study was carried out to evaluate the effects of soil application of humic acid and calciumon morphophysiological traits and Na+, Mg^2+, Ca^2+ uptake of Pistachio seedling (Akbari) grown under salt stress.  A completely randomized design was used with four replications in greenhouse conditions. The experimental treatment consisted of four levels of humic acid (Bis humic) (0, 4, 8 and 12 gr kg^-1 soil) and antisalt as a source of Ca+2 (0, 1, 2 and 3 gr kg^-1 soil). Results indicated that humic acid and  antisalt significantly increased vegetative growth, such as root fresh and dry weight, stem diameter, leaf number and leaf area, of pistachio seedling in comparison with the control group (p<0.05). However, no significant differences in fresh and dry weight of shoot of pistachio seedling were detected in all treatments except in humic acid 8 gr kg^-1 soils. The results indicated that the application of humic acid and antisalt decreased Na+ absorption in pistachio seedling in all experimental treatments (p<0.05). No significant differences in Ca^+2 and Mg^+2 absorption were detected in all treatments. Results showed a significant reduction of the electrical conductivity (EC) and sodium adsorption ratio (SAR) in all levels of humic acid and antisalt in soil.  However, in these treatments, there were no statistically significant differences in the pH. The best concentration of humic acid and antisalt was 8 gr kg^-1 soil and 3 gr kg^-1 soil, respectively. This study revealed the relative importance and efficiency of humic acid and antisalt to salinity stress tolerance in pistachio seedling.