Comparison the effect of ZnSO4 and Zn- lysine aminio chelate foliar application on growth indices of Behbahan onion

This field experiment was conducted to investigate the effect of foliar application of zinc (Zn) in the form of ZnSO4 and Zn-Lys amino chelate on growth indices and yield of Behbahan onion at the Agriculture Research Station of Behbahan, Iran. The experiment was conducted in a randomized complete block design with four treatments and three replications. Foliar application treatments were: ZnSO4, Zn chelated with lysine (Zn-Lys), and free amino acid of lysine (Lys). A treatment with no foliar application of Zn and amino acid was considered as the control. Foliar application was performed at two stages, once at the early rapid vegetative growth stage and the other at the early bulbing. The results of growth analysis indicated that at all fertilizer treatments, the slow growth period lasted to 125 days after seed germination followed by the rapid growth period. The maximum leaf area index (LAI) (4.19), bulb growth rate (30.49 g m-2 day-1), crop growth rate (39.66 g m-2 day-1) and total and marketable yield of bulb (63.07 and 60.54 t ha-1, respectively) was obtained at the Zn-Lys amino chelate. Among different treatments, the pattern of dry matter accumulation showed that Zn-Lys amino chelate resulted significant increase of plant dry mass (62% over the control treatment), and this trend continued until the end of the growing season. A positive and significant correlation (P