Effects of Deficit Irrigation on Some Morphological Characteristics of Grape (Vitis vinifera cv. ʽAsgariʼ) Symbiosis with Arbuscular Mycorrhizal

Abiotic stresses, in particular drought, not only compromise crop quality and limit yield, but also restrict the geographical range over which crop production is viable. Plant species have evolved a number of physiological and molecular means to cope with adverse environmental conditions. Grapevine is a perennial crop grown in various areas around the world. It is highly responsive to local environmental conditions and viticultural practices. Abiotic stresses cause extensive losses to agricultural productivity. Grapevine is no exception to the rule and faces several abiotic stresses throughout its lifespan. Drought, salinity, or heavy metals are serious problems in many parts of the world. The potential of AMF to enhance plant tolerance to abiotic stress conditions has long been known, and their use in sustainable agricultural systems will be of tremendous importance for soil quality and crop productivity under severe edapho-climatic conditions. Arbuscular mycorrhizal fungi (AMF), a kind of beneficial soil microorganism, can create a symbiotic association with plant roots forming arbuscular mycorrhizas (AMs), which play a role in the regulation of plant growth. This research was carried out in order to determine the effect of deficit irrigation on morphological characteristics of grapevine ʽAsgariʼ cultivar in greenhouse conditions in 2016. The layout was as a factorial experiment in a completely randomized design with three replication and two factors, including Arbuscular mycorrhizal and irrigation regimes. Irrigation treatments were irrigation with 100% moisture content of field capacity (control), 70% moisture content between field capacity and permanent wilting point (MAD 30) and 40% moisture content between field capacity and permanent wilting point (MAD 60) and mycorrhizal treatments was including non-use of mycorrhizal and use of Glomus mosseae, G. intraradices, G. etunicatum and G. verciform. Some morphological traits including height, root length, root volume and root density, fresh and dry weight of leaf, stem and root, leaf area, number of leaf damage, leaf area, leaf diameter and symbiosis percent of grape roots with fungi were measured. The results showed that mycorrhizal and 100% irrigation treatments increased the fresh and dry weight of leaf, stem and root, leaf area and the percentage of mycorrhizal symbiosis. Due to irrigation, the indices measured in the experiment such as height, fresh and dry weight of root, leaf and stem decreased, so that the decrease in without mycorrhizal plants was more than the with mycorrhizal plants. Generally, the use of mycorrhiza in this research has reduced the damaging effects of water stress on the morphological characteristics of grapevine, which in between the G. verciform and G. etunicatum were better than the G. mosseae and G. intraradices. Grapevine phosphorus deficiency is usually rarely observed, not only mainly because of limited phosphorus requirement, but also because of sufficient phosphorus richness in the majority of vineyard soils and remobilization from bark, wood, and roots during periods of high P demand. Nevertheless, P deficiency have been described in vineyards in Australia, France, Germany and USA. Phosphorus deficiency symptoms correspond to stunt shoot growth, decrease in dry matter, and berry clusters. Mycorrhizal treatments helped in alleviation of drought stresses. Enhanced uptake and storage of P, beyond what is required for immediate vegetative growth may be of particular importance for heavily pruned crops like grapes, since most of the new shoot growth is removed every year. These results were achieved in the greenhouse under almost controlled conditions and can be difficult to suggest for applying in the field conditions. Such experiments may be organized in the field conditions. Present-day vineyard practices place several constraints on the use of functions provided by mycorrhiza. The risk of large, costly, or irreversible changes is to be reduced or averted. Future (modern) agriculture should be based on the implementation of ecological management practices that deliberately maintain resilience of ecosystem services. This means integrating the development of vineyard management strategies that optimize the impact of beneficial microbes like mycorrhizal fungi on production. Furthermore, AMF vary in their ability to provide ecological services so that suitable tools have to be defined to fully assess their contribution. Molecular tools have considerably improved the possibility to identify and monitor mycorrhizal fungi in ecosystems, but a quick and reliable test for assessing their functionality is still lacking. For producers’ expectations to be met, a novel industry encompassing soil/mycorrhiza analyses and advice to producers/managers is needed. Additional barriers to rationally exploiting beneficial soil microbes like mycorrhizal fungi as ecosystem services range from economical, technical, and cultural aspects to legislative questions. In spite of this, considerable progress has been made in the last decade for crop plants in general, but also for grapevine, towards the use of AMF.