Partial Exchange of Mineral N Fertilizer for Common Bean Plants by Organic N Fertilizer in the Presence of Salicylic Acid as Foliar Application

Common beans are very significant for poor countries, because they provide high nutritional value, especially in terms of protein, calories, and trace nutrients, to people who cannot afford more expensive forms of nourishment. The current experiment was performed to investigate the influence of four different levels of organic fertilizer (compost) in the presence of mineral N fertilizer, i.e., T-1: 25% M-RDN +75% O-RDN; T-2: 50% M-RDN +50% O-RDN; T-3: 75% M-RDN +25% O-RDN; and T-4 (control): 100% M-RDN (O-RDN, M-RDN = recommended dose of N in organic and mineral forms, respectively; RDN: 60 kg N/fed.) and foliar spray with salicylic acid (SA) at 0, 50, 100, and 150 ppm, as well as of their interaction, on vegetative growth, productivity, and seed quality of common bean (Phaseolus vulgaris L.) cv. Nebraska. Obtained results showed that the tallest plants, the highest number of branches per plant, and the heaviest leaf fresh and dry weight per plant were scored using the combined treatment comprising T-4 (100% M-RDN) and SA at 150 ppm in the two seasons. T-4-fertilized and 150 ppm SA-sprayed plants induced the highest values of leaf N, P, K, and total carbohydrates (%). The highest seed yield per plant and hectare as well as the highest average weight of 100 seeds were achieved by plants fertilized with T-4 or T-3 treatments (75% of M-RDN +25% O-RDN) and sprayed with 150 ppm SA in the two seasons. The combined treatment of T-4 and SA at 150 ppm caused the statistically highest values of seed N%, P%, total protein (%), K%, and total carbohydrate (%). In addition, the lowest values of seed nitrate content were achieved by plants fertilized with the T-1 treatment (25% M-RDN +75% O-RDN) and receiving 150 ppm SA foliar spray. In conclusion, for enhanced growth, productivity, and quality of common bean plants, it could be safe to fertilize with 75% M-RDN +25% M-RDN and spray these plants with SA at 150 ppm.