Effects of potassium and phosphorous on growth and yield of soybean variety VNUAĐ2 in Gia Lam – Ha Noi

The experiment was carried out to determine effects of potassium and phosphorus fertilizers on growth and yield of the soybean variety VNUAĐ2. The experiment was conducted in the spring season of 2021 and was a split-plot design with 3 replications. Potassium levels included 0, 60, 80 and 100 kg/ha and phosphorous levels were 0, 70, 90 and 110 kg/ha. The effects of different fertilizer rates were determined through growth and development characteristics (plant height, number of leaves, number of nodes, number of branches), leaf area index, number and weight of nodules, yield components and yield. Results showed that phosphorus and potassium fertilizer application resulted in better plant growth and development than no fertilizer application. Also, the average plant height (47.4 to 50.5 cm), number of branches (2.2 to 2.6), number of nodules in the flowering period (51.2 to 56.3) and yields (1.77 to 1.81 tons/ha) with phosphorus application were better than the plant height (46.1 cm), number of branches (2.0), number of nodules (48.1) and yield (1.74 tons/ha) without phosphorus application. Different levels of fertilization affected the growth and development of VNUAĐ2 variety and its yield. The level of application of potassium (80 kg/ha) and phosphorus (90 kg/ha) significantly increased yield components and yield by 10,1 - 50% as compared with no fertilizer application. When compared with other fertilization levels, the application of potassium (80 kg/ha) and phosphorus (90 kg/ha) resulted in better total pod number of 38.1 pods/plant (30.9 - 36.5% higher), number of filled pods of 36.7 pods/plant (6.70 - 31.5% higher), percentage of 3-seeded pods of 12.9% (6.6 - 29.0% higher), individual yield of 11.42 g/plant (0.53 - 14.1% higher) and yield of 1.86 tons/ha (1.1 - 8.8% higher). Thus, the most suitable fertilizer rate for the soybean variety VNUAĐ2 in the spring season was 80 kg/ha of potassium and 90 kg/ha of phosphorus.