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The current study was aimed to assess the effects of different iodate concentrations on morpho-physiological characteristics of potato. In this regard, a pot experiment was carried out during the spring and summer 2013. Five concentrations of KIO3 including control beside 10, 20, 40, and 80 mg/Kgsoil were applied through irrigation system. The results showed that all selected agronomical and morphological characteristics of potato except dry weight of stem (SDW) and root (RDW) were negatively affected by high iodate concentrations. The results showed that applying 80 mg KIO3/Kgsoil compared to control resulted in around 15, 86, 84, 41, 16, 25, 20, and 87% reductions in harvest index (HI), leaf dry weight (LDW), tuber dry weight (TDW), plant dry weight (PDW), stem length (SL), root length (RL), plant height (PH), and number of tuber per plant (NT), respectively. Iodate application (80 mg KIO3/Kgsoil vs. control) also affected potato’s physiological characteristics including chlorophyll content (SPAD), relative water content (RWC), water use efficiency (WUE), evapo-transpiration efficiency (ETE), cell membrane stability index (CMSI) and tolerance index (TI) showing around 27, 12, 87, 39, 40, and 77% reductions for each one, respectively. Increasing iodate concentrations, although, showed no effect of Zn concentration of root and Fe and Mn concentrations of leaf, gradually decreased Zn concentration of leaf and increased Fe and Mn concentrations of root and Cu concentrations of root and leaf. Plants also showed several visible symptoms including stunting, chlorosis, browning of leaf tip and reduction in growth due to iodate toxicity.

Zinc (Zn) is an essential mineral nutrient for plant and human growth, and dietary Zn deficiency is a worldwide nutritional problem. Two-year field experiments were conducted during the 2013 and 2014 to evaluate the effects of foliar application of zinc sulfate at the developmental stages on agronomy traits and grain Zn content. The following foliar applications of Zn (0.44 g Zn/lit) at the phenological stages were used: (1) no Zn fertilizer addition (control), (2) stem elongation stage and (3) stemming and grain filling stages. The results showed that foliar Zn application at the stemming and grain filling stages was much more effective than foliar Zn application at the stem elongation stage on grain yield and its components of wheat. Foliar application at stemming and grain filling stages had no significant effect on the harvest index whereas significantly increased plant height. Zn concentration was not changed when plants were sprayed at early stem elongation while significantly increased grain yield and its components. In general, the most effective treatments to ameliorate Zn deficiency were foliar application at stemming and grain filling stages.