Spinach (Spinaceae oleraceae L.) is one of the most enrichment leaf vegetable used by people in the globe. Inadequate micronutrients especially zinc in most Iranian soils have formed a major constraint to spinach production. Therefore, a study was conducted in 2008 growing season in Kohnekan region of Bojnourd to investigate the effects of foliar application of zinc on physiological indices and yield of three cultivars of spinach. A factorial experiment was laid out based on Randomized Complete Block Design (RCBD) with three replications. Treatments were three spinach cultivars (Virofly, Tehrani, and Irani) and two levels of Zinc micronutrient (foliar and non-foliar application). Results showed that Zinc micronutrient had no significant effect on total dry matter (TDM), leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR) and specific leaf area (SLA) indices. The differences among the cultivars for growth characteristics were significant, but interaction effect of Zinc levels with cultivars was not significant. Also, Zinc micronutrient had significant effect on dry matter yield. Generally the results showed that although there is no significant difference between Zinc foliar application and control, numerical difference however existed in most trait in this experiment.

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