Department of Horticulture, Damghan Branch, Islamic Azad University, Damghan, Iran
Damghan Pistachio Research Station, Iran
Brassinosteroid as one of steroid hormones has an integral role in controlling plants physiological process especially in response to biological and non-biological stress. This research has been done in Damghan Islamic Azad University Greenhouse. The influence of four concentrations of plant growth regulator -24, homobrassinolide with concentration of 0,10-10, 10-8,10-6 molar on null seedlings of pistachio genotype sort based on factorials experiments on the basis of completely randomized block design with four replications was performed. After foliar spraying in six -leaves stage of pistachio seedlings and after passing six weeks, somephysio-morphplogical characteristics such as the size of photosynthesis pigments, leaf area index, seedlings height, biomass (the wet and dry weight of root and shoot), and lipoxygenase enzymes were scrutinized.The result indicated that foliar spraying experiment with brassinosteroid hormones had significant effect on some evaluated traits (P). Maximum leaf area index with concentration of 10-10 brassinosteroid and genotype G1, and the minimum leave area index with untreated (control) and genotype G5 were achieved. In biomass scrutiny, the wet weigh of aerial organs in level 1% was significant (5% level).The maximum weight of the wet weigh in concentration, 10-10 and the minimum weight in concentration of control and 10-6 were observed. Besides, the fresh weight of root in level 1% was significant, and the maximum weight with concentration of 10-10and genotype G (22%) and minimum weight with control concentration and genotype G1 were observed. The maximum amount of lipoxygenase was related to concentration of 10-10, and genotype G2 and the minimum amount was related to null concentration of brassinosteroid hormones and genotype G1.