Evaluation of the role of zinc nano- chelate and mycorrhizae on biochemical properties of leaves and root yield in sugar beet (Beta vulgaris. L) under irrigation treatments

To evaluate the effect of zinc nano-chelate and mycorrhizae on the biochemical properties of leaf and root yield under different irrigation levels, a split-plot design based on randomized complete block design with three replications was conducted in 2019. Irrigation treatments including irrigation after 60-, 90-, and 120-mm of evaporation from class A pan were allocated to the main plots and fertilizer treatments (control, inoculation with mycorrhiza, zinc nano-chelate, and zinc nano-chelate + mycorrhiza) to the sub-plots. In this study, irrigation after 120 mm of evaporation reduced the amount of chlorophyll a (17.01%), chlorophyll b (8.09%), carotenoid content (28.78%) and superoxide enzyme inhibition (31.14%), and increased leaf flavonoid content (25.47%), compared with irrigation after 60 mm of evaporation. Among the fertilizer treatments, zinc nano-chelate + mycorrhiza treatment had the highest chlorophyll-a (9.30 mg/g fresh weight), chlorophyll b (3.84 mg/g), carotenoid content (3.94 mg/g), superoxide enzyme inhibition (33.53 percent). The interaction effect of irrigation and fertilizer in irrigation after 60 mm of evaporation along with nano-chelate zinc + mycorrhiza fertilizer treatment had the highest nitric acid radical inhibition (23.45 percent) and root yield (82.62 t/ha), and the lowest leaf proline content (0.49 mg/g), as well as leaf phenol content (34.19 mg of gallic acid/ g dry weight). In this study, application of mycorrhiza, especially under water deficit conditions, through improving biochemical properties and regulation of antioxidant enzymes activity, was able to moderate the effect of water stress on root yield and also increase root yield compared with control.