Evaluation of Symbiotic Relationship between Mycorrhizal Species and Soybean under Partial Root-Zone Drying Irrigation System

To evaluate mycorrhizal symbiosis of soybean plants (Glycin max L. cv. Williams) in different irrigation systems, a split plot experiment was conducted based on randomized complete block design (RCBD) at Urmia University in 2015. Treatments were irrigation systems (constant partial root- zone drying irrigation: CPRD, furrow and alternate partial root-zone drying irrigation: APRD) as main plots, and mycorrhizal fungi species (non-inoculated control, Funneliformis mosseae, Rhizophagus intraradices and Simiglomus hoi) as sub-plots in three replications. The leaf area index, specific leaf area, leaf area ratio, leaf weight rate, seed protein, leaf total soluble sugars, leaf proline, nod number per plant, pod weight and oil percentage were not affected by irrigation systems and mycorrhizal species. Values of leaf phosphorus and potassium were the same for all irrigation systems. In spite of highest chlorophyll index (SPAD) in APRD, the maximum percentage of harvest index for oil and seed production belonged to furrow system. Plants inoculated with S. hoi exhibited the highest values of SPAD, leaf P and leaf K, though the highest percentage of harvest index (for seed and oil production) were occurred in plants inoculated with R. intraradices. The significant interaction effects exhibited variable responses of soybean plants to mycorrhizal species under different irrigation systems. Although, the highest root colonization and leaf nitrogen were respectively observed at APRD and furrow irrigation systems of mycorrhization by F. mosseae. The optimal performance including plant height, 100-seed weight and yields (biological yield, seed yield and oil yield) of soybean plants were obtained from mycorrhizal plants of furrow irrigation identically for three species of fungi. While the higher contents of Linolenic and Linoleic fatty acids in mycorrhizal soybean plants, Gadoleic, Oleic acids (unsaturated fatty acids), Myristic, Palmitic and Stearic acids (saturated fatty acids) were in more amounts in non-AMF inoculated plants. Palmitoleic and Arashidic fatty acids for furrow irrigation, Linolenic and Linoleic fatty acids for APRD, and Gadoleic, Oleic, Myristic, Palmitic and Stearic fatty acids for CPRD were found to be the higher contents.