THE EFFECT OF MYCORRHIZAL SYMBIOSIS AND SEED PRIMING ON THE AMOUNT OF CHLOROPHYLL INDEX AND ABSORPTION OF NUTRIENTS UNDER DROUGHT STRESS IN SESAME PLANT UNDER FIELD CONDITIONS

Plants are exposed to environmental stresses during their growth. One of the most important stresses is drought stress, which can affect the absorption and transfer of nutrients to the plant. The use of advantageous microorganisms such as mycorrhizal fungi as well as seed priming are among the solutions that have been taken into consideration in many plants in recent years to mitigate the effects of water shortages and drought stress. In the present study, the effect of mycorrhizal symbiosis and seed priming on the amount of chlorophyll index and absorption of nutrients in sesame oilseed under drought stress was investigated during 2013 and 2014 at the farm of Hajiabad Agricultural Research Station in Hormozgan- Iran. The main drought stress factor included irrigation based on providing 100% of the plant's water requirement (normal irrigation), providing 70% of the plant's water requirement (mild stress) and providing 50% of the plant's water requirement (severe stress), Priming substrate was at three levels: no priming (control), hydro-priming and osmo-priming, and another sub-factor consisted of mycorrhiza fungi species: without inoculation mycorrhizal fungi (control), using Glomus mosseae and Glomus intraradices. The results of combined analysis of variance showed that the effects of drought stress and mycorrhizal symbiosis on leaf chlorophyll index, nitrogen (N), phosphorus (P), potassium (K), iron (Fe), zinc (Zn) and copper concentration (Cu) in leaf were significant. Sodium concentration was only significantly affected by drought stress and seed priming was only effective on Cu concentration. Interaction of irrigation x mycorrhizal symbiosis was significant on pand Cu uptake and interaction of irrigation x seed priming was only significant on iron concentration. Results showed that severe drought stress (providing 50% of plant water requirement) had the highest effect on decreasing amount of chlorophyll index and concentration of nitrogen and phosphorus elements in leaves, whereas concentrations of potassium, zinc, iron, copper and sodium increased with drought stress. Inoculation with mycorrhizal fungi increased the amount of chlorophyll index, nitrogen, phosphorus, potassium, zinc, iron and copper uptake compared with the absence of mycorrhizal fungi.