The role of arbuscular mycorrhizal fungi in establishment and water balance of tomato seedlings and sweet cherry cuttings in low phosphorous soil

Extreme variability in water availability during the growing season makes sweet cherry fruit more prone to cracking. Therefore, experiments were designed to explore how mycorrhizal colonization of cherry roots may influence water regulation, as well as enhanced growth performance. Arbuscular mycorrhizal fungi (AMF) are obligate mutualists from the Order Glomales and most fruit trees establish associations with AMF naturally when transplanted to the field, particularly in low phosphorous conditions. Although plants benefit from this symbiotic relationship through increased nutrient uptake especially phosphate, management practices influence the presence of mycorrhizal colonization in the field. This project has investigated the early growth rate and establishment of cherry (and tomato plants as a model system) inoculated with Rhizophagus irregularis (syn. Glomus intraradices). After one month of growth, the number of leaves of mycorrhizal tomato seedlings was significantly increased and the height was approximately doubled in response to inoculation compared with non-inoculated tomatoes. In addition, a significant effect of AM fungi on cutting survival was observed, where 65% of inoculated cherry rootstocks survived after two months from striking, compared to 45% of non-mycorrhizal cherries. The effect of AMF on water uptake is currently being investigated in both sweet cherries and tomatoes to determine how colonization affects water uptake and photosynthesis during periods of drought and excess water conditions.