Effects of Serendipita indica inoculation of four wheat cultivars on hydraulic properties and aggregate stability of a calcareous soil

We investigated the effect of Serendipita indica, an endophytic fungus, inoculation of different wheat (Triticum aestivum) cultivars on the rhizosphere physical quality. S. indica inoculated and uninoculated seedlings of wheat cultivars (Roshan, Ghods, Kavir and Pishtaz) were grown in rhizoboxes. Plants were harvested and intact samples were taken from the rhizosphere to measure soil organic carbon (SOC), hot-water soluble carbohydrates (HWSC), carbon mineralization rate (CMR), water repellency index (RI) by the sorptivity method, and aggregate stability by the high energy moisture characteristic (HEMC) method. Root mucilages of inoculated and uninoculated seedlings were also collected for measuring total polysaccharides (TPmucilage). The SOC, HWSC, and RI were increased by 146, 83, and 40% and CMR was decreased by 56% in planted treatments, which consequently increased the HEMC aggregate stability indices. S. indica increased SOC, HWSC, RI, and structural stability, and improved the physical quality especially in soil with Roshan and Ghods, which had more extensive root distributions and higher TPmucilage. The changes of soil-physical and hydraulic properties among different wheat cultivars imply that both quantitative and qualitative properties of root exudates have significant effects on soil quality. Soil with Roshan had the highest SOC, HWSC, and root distribution and the lowest aggregate stability. However, soil with Ghods had almost the same SOC and HWSC, but it had the highest stability indices. S. indica inoculation of different wheat cultivars, by increasing SOC and inducing water repellency in the rhizosphere, can improve the aggregate stability and soil physical quality.