Effect of Arbuscular Mycorrhizal Fungi on Water Relations and Growth of Young Plum Trees under Severe Water Stress Conditions

Abstract

Aims: Arbuscular mycorrhizal fungi (AMF) can mitigate plant response to severe water stress. On this basis, an experiment was carried out under field conditions to evaluate the effect of arbuscular mycorrhization, realized by a mixture of two AMF species, Rhizophagus intraradices and Funneliformis mosseae, on drought tolerance of young plum trees. Study Design: The experimental design was a criss cross with three variable factors: water regime, mycorrhization and plum variety. Place and Duration of Study: the trial was conducted during one year (2013) under field condition in experimental station Ain Taoujdate of the Regional Agricultural Research Center of Meknes, in northern Morocco. Methodology: The experiment was performed on four one year old mycorrhizal and non-mycorrhizal plum varieties submitted to two water regimes, 50% and 100% of crop evapotranspiration (ETc). Measurements have concerned vegetative growth parameters (shoot elongation, trunk growth and leaf area), water status (predawn and midday leaf water potential, stomatal conductance and leaf relative water content) and leaf phosphorus content). Results: the young plum trees, even mycorrhized, did not tolerate water stress applied. However, plants were dependent on AMF under water stress, highly compensating its effects even at 50% of ETc. The compensatory effect of AMF was related to an increase of water potential and stomatal conductance without changing relative water content of plants. AMF also induced a significant increase of phosphorus uptake under water stress. Conclusion: it was demonstrated that AMF significantly improve water and nutrient use efficiency of young plum trees submitted to water stress amounting to 50% of ETc. The observed improvements due to AMF were considerable, suggesting possibility of adoption of this water restriction to optimize deficit irrigation of mycorrhizal plants of this rosacea under low water availability conditions.