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

Plant growth and photosynthetic rate are affected by water deficit and high temperature as environmental factors in many areas. 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 mychorizal arboscular (Glomus etunicatum) on growth and physiological traits was considered in two grape cultivars („Perllet‟ and „Yaghouti‟) under two irrigation levels (water deficit for 9 days and field capacity regimes) and three temperature levels (25¡ 40¡and 40°C). This experiment was conducted on the basis of randomized complete block design with 4 replications in a greenhouse. Results indicated that fresh and dry weight were decreased in two cultivars („Perllet‟ and „Yaghouti‟) under drought stress¡ high temperature stress was not effective on photosystem II efficiency alone¡ but drought stress decreased photosystem II efficiency. However photosystem II photochemical efficiency was decreased more when drought and high temperature stresses were combined. The fungus improved tolerate of the perllet cultivar which were under drought stress and 40 °C temperature. Therefore¡ the fungus prevent decrease of the chlorophyll index in this cultivar. Both Perllet‟ and „Yaghouti‟ cultivars were recovered during 4 days. Generally these cultivars were resistant to high temperature stress but their growth rate decreased under combind drought and high temperature stresses.