Effect of Different Levels of NPK Fertilizers with the Foliar Application of Iron, Zinc and Boron on Vegetative Growth and Yield of Cowpea

Abstract

Two experimental trials were carried out in the two successive seasons of 2014and 2015 to investigate the effect of five NPK fertilizers levels and foliar spraying with some micronutrients on cowpea plant. The experiment consisted of five treatments of fertilizers levels (50%, 75%, 100%, 125%, and 150% RDF) of NPK and three rates of mixtures of (6%Fe, 5% Zn and 1% B)beside a control. A split plot in a randomized complete blocks design with three replicates was used. Results can be summarized as follows: increasing applied fertilizer NPK at rate from (50% to 150 % RDF) lead to significantly increase in plant height, plant fresh and dry weight, leaf area/plant chlorophyll b content as well as seed yield and its components, i.e., seed yield/plant, seed yield/fed, number of pods/plant, number of seeds/pod, pod length and weight of 100-seeds weight and some chemical content of plant and seeds of cowpea. But the higher values were recorded after application with use applied fertilizers at rate 100%RDF in the two seasons. On the other hand spraying cowpea plant with(6% Fe, 5% Zn and 1% B)mixture significantly increased all the previous traits in all experiment investigated compared with control (without foliar).The foliar mixture(6% Fe, 5% Zn and 1% B) gave a superior value in both seasons. Since; it produced the highest values of plant height, number of leaves/plant, number of branches/plant, leaf area/plant, seed yield and its components and percentage of crud protein of seeds content. According to the mentioned results, the recommendation is application of NPK at rate 100%RDF with foliar mixture of micronutrients at rate 3g/l three times so as to give the highest cowpea seed yield and its quality.