Influence of Organic, Phosphate Fertilization and Spraying of L-Glutamic Acid on Growth and Yield of Cowpea

A field experiment was carried out in summer season 2024 at one field of the Agricultural Engineering Sciences College, University of Baghdad, in order to study the impact of organic and phosphate fertilization plus foliar application with the L- glutamic acid, on growth and yield of cowpea (Vigna unguiculata L.). The experiment was laid out in a randomized complete block design (RCBD) with split-plot arrangement and three replicates. The experiment consist three factors, three levels of organic fertilizer (cattle manure) at rates 0, 20, and 40 Mg ha⁻¹; three levels of phosphate fertilizer in the form of diammonium phosphate (DAP, 20% P) at a rate 0, 75 and 150 kg ha⁻¹, and foliar aaplication of L-glutamic acid at concentrations 0, 134, and 267 mg L⁻¹. The results revealed that the combined treatment 40 Mg ha⁻¹ organic fertilizer, 150 kg ha⁻¹ phosphate fertilizer and 267 mg L⁻¹ L-glutamic acid foliar application significantly improved the plant growth parameters (number of leaves, plant height, leaf area, dry biomass and number of root nodules). This treatment also resulted in the maximum number of pods, branches, chlorophyll concentration, green pod yield and N,P% in seeds.