Yield-related biochemical response of understory mycorrhizal yellow sweet clover (Melilotus officinalis L.) to drought in agrisilviculture

Abstract

ABSTRACT In the present study, the effects of arbuscular mycorrhizal fungi, Funneliformis mosseae and Rhizophagus irregularis, on oxygen radical scavenging system (superoxide dismutase, catalase and peroxidase), osmotic adjustments (proline and soluble carbohydrates), relative water content, root colonization, leaf nutrients (N, P, K) and biological yield of Melilotus officinalis under rainfed and supplemental irrigation were studied in the morning and the afternoon light conditions in agrisilviculture system. A 2-year split-plot experiment was carried out using randomized complete block design with three replications in a plum (Prunus domestica (L.), Opal) orchard. Antioxidant activity was stimulated more in no-mycorrhizal inoculated plants in both of the irrigation systems for both of the light conditions. Enzymatic and non-enzymatic antioxidants were decreased in mycorrhizal stressed plants. Despite the increase in the leaf total chlorophyll in mycorrhized plants, the concentrations of carotenoid were decreased. In irrigated plants, significant increases of biological yield and leaf nutrients were observed in the morning light condition for mycorrhization, similar to the rainfed. Inoculation with F. mosseae generated more biological yield in the morning light area. Water status improvement through declined antioxidant activity and osmolytes accumulation in mycorrhized plants resulted in compensation for yield loss. Abbreviations: AMF: arbuscular mycorrhizal fungi; CAT: catalase; Funneliformis mosseaeL F. mosseae, H2O2: hydrogen peroxide; MDA: malondialdehyde; POX: peroxidase; ROS: reactive oxygen species; Rhizophagus irregularis, R. irregularis; RWC: relative water content; SOD: superoxide dismutase; TSS: Total soluble sugar.