Physiological Responses of Two Grapevine Cultivars to Combined Water Deficit and High Temperature Stresses in Presence of Mycorrhizal Fungus

Water shortage and high temperature are the most important environmental factors in many parts of the world that threat the plant growth. Whereas most of the time, both of these stresses happen synchronous, few information has already been reported about their interaction effects on plants and also the role of mychorizal arboscular in these conditions. In this research, the effects of mychorrizal arboscular (Glomus etunicatum) on growth and physiological traits was considered in two grapevine cultivars (Perllet and Yaghouti) under two irrigation levels (water deficit for 9 days and full irrigation regimes) and three temperature levels (25, 40,and 45 ºC). This experiment was conducted on the basis of randomized complete block design with 4 replications in a greenhouse. Results indicated that fresh and dry weights were decreased in two cultivars under drought stress. High temperature stress was not effective on photosystem II efficiency solely, but drought stress decreased photosystem II efficiency. However photosystem II photochemical efficiency was decreased more when drought and high temperature stresses were combined. Proline accumulation in plants only under drought stress and in combination with high temperature was observed. Root colonization in both cultivars increased under drought stress, but under combined drought and high temperature stresses (45 ºC) reduced. Both Perllet and Yaghouti cultivars were recovered during 4 days. In general, these cultivars were resistant to high temperature stress but their growth rate decreased under combined drought and high temperature stresses.