1401 AJCS 13(09):1401-1408 (2019) ISSN:1835-2707 doi: 10.21475/ajcs.19.13.09.p1174 Effects of arbuscular mycorrhizal fungi (Glomus mosseae) on growth enhancement and nutrient (NPK) uptake of three grape (Vitis vinifera L.) cultivars under three different water deficit levels Azimeh Kamayestani 1 , Mehdi Rezaei 1 *, Ali Sarkhosh 2 , Hamid Reza Asghari 1 1 Faculty of Agriculture, Shahrood University of Technology, P.O. Box 3619995161, Shahrood, Iran 2 Horticultural Sciences Department, University of Florida, Gainesville FL 32611 USA *Corresponding author: mhrezaei@shahroodut.ac.ir Abstract We tested the effects of arbuscular mycorrhizal fungi (AMF) and three levels of water deficit on growth enhancement, physiological performance and nutrient uptake of three local Iranian grape cultivars. Mycorrhizal inoculation (Glomus mosseae) showed a significant increase in grape's growth characteristics, and variation was observed among the cultivars and field capacity percent (FC %) levels. Mycorrhiza inoculation increased significantly (p<0.05) the number of leaves in ‘Pikani’ and ‘Shahroudi’. The results showed that water deficit significantly increased the chlorophyll index and decreased the stomatal conductance, leaf relative water content (RWC), leaf area index, nitrogen (N%) content, and increased proline content (P<0.05). Water deficit and mycorrhiza increased potassium (K%) in all cultivars and phosphorous (P%) in two cultivars (‘Shahrudi’ and ‘Keshmeshi’) significantly (P<0.05). By increasing the water deficit level, ‘Shahrudi’ and ‘Keshmeshi’ showed more relative drought resistance than ‘Pikani’. The cultivar ‘Shahrudi’ showed a better symbiotic interaction with mycorrhiza and more resistance to water deficit in some traits in comparison to other two cultivars. Keywords: field capacity, growth characteristics, mycorrhiza, NPK%, physiological performance. Abbreviations: Arbuscular mycorrhizal fungi (AMF), field capacity percent (FC), nitrogen (N), phosphorus (P) and potassium (K), Relative water content (RWC), Introduction Grape, (Vitis vinifera L.), is one of the most important fruit crops of the world. A large proportion of vineyards are located in regions with seasonal drought and atmospheric water deficits, together with high temperatures, including Iran (Chaves et al., 2010). The global climatic changes also increase the frequency of heat waves in large parts of the world. Furthermore decrease in annual mean precipitation in many mid-latitude, and dry subtropical regions make it more erratic (Zandalinas et al., 2018). This scenario will affect crops to a greater range and number of abiotic stresses such as drought stress which is the primary cause of crop loss worldwide, reducing average yields and quality (Awasthi et al., 2014; Teskey et al., 2015). Drought stress has adverse effects on different plant growth parts by hampering key metabolic attributes including nutrient uptake and assimilation, enzyme activity, photosynthesis, protein synthesis and antioxidant metabolism (Hameed et al., 2014; FanizzaRicciardi, 2015). In recent irrigation model of viticulture, deficit irrigation emerged as a tool to mitigate the negative impact of drought on yield and quality and to save water (Chaves et al., 2010; FanizzaRicciardi, 2015; Merli et al., 2015). The effect of deficit irrigation on water savings and drought stress varies with the genotype (scion and rootstock), the environmental conditions as well as the adopted agronomic strategies (Permanhani et al., 2016). Moreover deficient irrigation and drought in viticulture reduced the amount of sugar in the berries, and their size (Keller et al., 2016). Several studies indicated that there is wide variations in water use efficiency among grapevine cultivars (Merli et al., 2015; Permanhani et al., 2016; Medrano et al., 2018). The best-adapted grape genotypes in water restriction in semiarid climate have the leaf cooling capacity and high water use efficiency (Chaves et al., 2016). High water use efficiency genotypes avoid dehydration by closing stomata, but under hot spells, they may reach supra- optimal temperatures (Bota et al., 2016). Therefore they must possess high mesophyll resilience to heat stress (Chaves et al., 2016). Among soil microorganisms, arbuscular mycorrhiza fungi (AMF) are capable of forming symbiotic associations with host plant roots (Trouvelot et al., 2015). AMFs are known to improve water uptake by plants and nutrient uptake at the same time (Kohler et al., 2008; Trouvelot et al., 2015). This mutualistic collaboration is based on biotrophic nutrient exchanges between the plant and the fungal companion. The host plant supplies the partner with carbon from photosynthesis (Trouvelot et al., 2015). The AMF boosts the ability of the plant through an extensive network of hyphae to absorb and accelerate water and minerals from areas unavailable to the plant root system (Hameed et al., 2014; Hashem et al., 2018). AMF communities are highly influenced by the soil characteristics, but also to a smaller