Foliar application of nano-chelate and non-nanochelate of zinc on plant resistance physiological processes in cotton (Gossipium hirsutum L.). Mohammadali Rezaei* and Hossein Abbasi

Nano-fertilizers are designed in order to gradually release their food contents. They are also manufactured in such a way that the time of their liberation matches with the food product requirement. The use of nano-fertilizers leads to an increase in the efficiency of the consumption of food elements. With regard to the strategic importance of cotton plant and the effects of zinc in increasing plant resistance, the purpose of this research study was comparing the effects of mineral fertilizer of zinc (Mi), chelate of zinc (Ch) and nan-ochelate of zinc (NCh) on the growth and some physiological and biochemical process of the cotton plant. To achieve this goal, the cotton plants in field were cultivated in a completely random design. The first phase of the foliar application of fertilizer was at the square stage or squaring (S) and the second and third stages were squaring-flowering (SF) and a week after flowering (F). Results showed the maximum height, fresh weight, and dry weight were obtained in treatments with nano-chelate and chelate of zinc and there were no significant difference in squaring, squaring-flowering, and flowering application stages. The height, fresh weight, and dry weight of cotton plant increased by application of fertilizers Co, Mi, Ch, and NCh in that order. Chlorophyll a and b increased in nano-chelate and chelate of zinc at squaring and flowering stages. Application of chelate and nano-chelate zinc fertilizer in the present study improved physiological processes in cotton as it increased the amount of chlorophyll and antioxidant activity of peroxidase, catalase, and polyphenol oxidase as a result of increase in fresh and dry weight. Findings suggest that application of zinc chelate and specially the nano-chelate of zinc can improve cotton performance by increasing the number of bolls per plant and mean weight of 20 bolls.