Effect of Native Mycorrhizal Fungi on Morphological and Physiological Traits of Judas Tree (Cercis siliquastrum) and Mesquite (Prosopis cineraria) Seedlings Under Drought Stress Conditions

Arbuscular mycorrhizal fungi (AMF) have a mutualistic relationship with a great number of plants. This can offer promising approaches to managing arid ecosystems. In the present study, the effects of native AMF inoculums were evaluated on morphological and physiological traits of Cercis siliquastrum and Prosopis cineraria seedlings under drought stress conditions. The study was carried out in two independent experiments as a full factorial design with two factors: AM fungal (non- AMF and AMF) and three levels of drought stress (80%, 50%, and 30% of field capacity). The results showed that shoot dry weight and root growth were reduced in response to an increase in drought stress levels on Prosopis cineraria. In C. siliquastrum, however, the shoot dry weight, root volume and root dry weight increased moderately as a result of AMF but decreased in response to severe drought stress. Native AMF inocula increased proline content by about two-fold, while also increasing root and shoot dry weight and root volume of the inoculated plants of both species. Drought stress increased proline content in both AMF plants and in uninoculated C. siliquastrum seedlings. The native AMF colonized the roots of C. siliquastrum and P. cineraria, by at least 80% and 70%, respectively, which was significantly higher than AMF from soils. Drought stress reduced catalase activity (CAT) in P. cineraria, but this was lower in inoculated plants than in uninoculated plants. In response to moderate and severe drought stress, ascorbic peroxidase (APX) activity increased by over 29 and 44%, respectively, compared to well-watered and inoculated P. cineraria seedlings. P. cineraria seedlings tolerated drought stress by both enzymatic and non-enzymatic ways, while C. siliquastrum accumulated osmotic solutes such as proline under drought stress. In conclusion, both species were recommended for xeriscaping purposes, although mesquite proved to be more reliable in adverse conditions.