Morpho-physiological, quantitative and qualitative Responses of Two Strawberry (Fragaria × ananassa) Cultivars to Heat Stress in Presence of Arbuscular Mycorrhiza Fungus

Heat stress is one of the most important weather phenomena that has caused destructive damaged many on agricultural crops, such as strawberries. For this purpose, five temperature treatments (control (23±2 days/16±2 nights), 30, 35, 40 and 45 °C) and two levels of mycorrhizal fungi (presence Funeliformis mosseae or absence) and tow cultivars of strawberry (Paros and Queen Elisa) as a factorial experiment in a completely randomized with four replications was performed in year 2016 in greenhouses at Shiraz university and Agricultural Research Center. The results showed that with increasing temperature, number of flowers in inflorescence, inflorescences per plant, percentage of fruit set, weight, length, diameter and achene of fruit, as well as plant yield decreased in both cultivars. The presence of mycorrhizal fungus on plants after the heat stress treatment increased colonization percentage, fresh and dry weights of root and shoot, leaf area, phosphorus, number of flowers and inflorescences, percentage of fruit set, fruit size, yield, total soluble solids and vitamin C was more than those of plants without mycorrhizal fungus. Plants in the presence of mycorrhizal fungus showed better tolerance to high temperatures than those without the presence of mycorrhizal fungus. The reduction of some evaluated characteristics was lower in cultivar of Paros compared to Queen Eliza at high temperatures which is demonstrated that, the tolerance of Paros cultivar was more at high temperatures. This study showed that the use of mycorrhizal fungi increased the quality and quantity of strawberry and improved heat stress tolerance.