جلال آرژه - Department of Plant Production and Genetics, Faculty of Agriculture , Urmia University, Urmia, Iran
علیرضا پیرزاد - Department of Plant Production and Genetics, Faculty of Agriculture, Urmia University, Urmia, Iran.
مهدی تاجبخش - Department of Plant Production and Genetics, Faculty of Agriculture , Urmia University, Urmia, Iran.
سویل محمدزاده - Department of Plant Production and Genetics, Faculty of Agriculture , Urmia University, Urmia, Iran.

In recent years, with the spread of drought and increasing demand for water, the need for water management in irrigation of plants has become more apparent. Present investigation studied yield-related biochemical responses of sugar beet to vermicompost and phytoprotectants to mitigate drought stress based on a split-plot-factorial design with three replications. The main plots consisted of irrigation at ۹۰%, ۷۰%, ۵۰%, and ۳۰% field capacity (FC). The subplots subjected to treatments comprised a factorial combination of vermicompost (۰ and ۷ Mg/ha) and foliar application of phytoprotectants [distilled water as a control, zinc (۵μM), silicon (۴mM), glycine betaine (۴mM) and ascorbic acid (۰.۵mM)]. The findings showed that concentration of ascorbate peroxidase, catalase, dehydroascorbate reductase, glutathione peroxidase, and superoxide dismutase, were significantly enhanced under stress conditions. Despite the higher sugar percentage, the lower root yield and biomass were recorded in the plants irrigated with ۳۰ and ۵۰% FC. Sugar content increased gradually in response to increasing in water deficit (from ۷۰% to ۳۰% FC). Root yield increased insignificantly with zink, glycine betaine, and ascorbic acid treatments. The highest root yield was obtained at ۷۰% FC that followed by other water regimes (۹۰, ۵۰, and ۳۰% FC, respectively). Malondialdehyde increased with increasing stress level but it decreased when phytoprotectants, especially glycine betaine, were applied. Vermicompost treatment had positive effect on the prevention of lipid peroxidation.  It can be concluded that phytoprotectants and vermicompost protect sugar beet plants from drought-induced oxidative stress, and improve root and sugar yield by enhancing plant water-stress tolerance.

Abscisic acid, Antioxidant, Beta vulgaris, Glycine betaine, irrigation, Silicon