Response of Growth Indices to Copper Foliar Application at Different Growth Stages of Cowpea

BACKGROUND: Copper is an essential plant nutrient that plays an efficient role in chlorophyll development, and protein formation from amino acids and gives rigidity to plant because copper strengthens plant cell wall. In all crops Cu is essential for more than 30 enzymes which acts as redox catalysts like nitrate reductase, cytochrome oxidase or act as dioxygen carrier like heamocynin. OBJECTIVES: The current study was conducted to evaluate the effect of different concentration and stage of foliar application of Copper on growth curves and crop production of Cowpea. METHODS: This research was carried out via factorial experiment based on randomized complete blocks design with three replications along 2017 year. The treatments included different concentration of Copper foliar application (a1: none use of copper or control, a2: 150 gr.ha-1, a3: 300 gr.ha-1, a4: 450 gr.ha-1) and Copper foliar application at different growth stage (b1: apply at vegetative stage, b2: beginning of flowering stage, b3: beginning of pod formation). RESULT: According result of analysis of variance effect of different concentration and growth stage of foliar application of Copper (instead crop growth rate) on all measured traits was significant at 1% probability level but interaction effect of treatments was not significant (instead seed yield). The highest seed yield with an average of 220 gr.m-2 of foliar application of 300 gr.ha-1 of copper in the vegetative and early flowering stage (which was not statistically significant with the treatment of foliar application of 150 gr.ha-1 of copper in the vegetative stage) and The lowest one was obtained from the non-foliar application of copper in the early stage of pod formation at the rate of 160 gr.m-2. CONCLUSION: Generally, due to the positive response of the cowpea to the copper in terms of growth, seed yield and its components, the use of copper fertilizer in fields where the concentration of this element in their soil is less than critical level, consumption of 150 gr.ha-1 of copper foliar application in the vegetative stage in Ahvaz region is recommended.