Effect of fertigating different levels of nitrogen, phosphorus, and potassium on greenhouse tomato (Lycopersicon esculentum L.) yield

摘要

Greenhouse studies were conducted to determine the optimum levels of N, P, and K applied through irrigation water for tomato yield. Three experiments were set up to study each nutrient element separately. In each experiment one nutrient was applied in 4 different levels while the other 2 were held constant at high levels. For N experiment, the rates were 125, 150, 175, and 200 ppm N with 70 ppm P_2O_5 and 200 ppm K_2O. For P experiment, the rates were 40, 50, 60, and 70 ppm P_2O_5 with 200 ppm N and 200 ppm K_2O. For K experiment, the rates were 140, 160, 180, and 200 ppm K_2O with 200 ppm N and 70 ppm P_2O_5. The experimental design was Randomized Complete Block Design with four replicates. In N experiment, the highest yield (99.9 t/ha) was obtained in 150 ppm N with 70 ppm P_2O_5 and 200 ppm K_2O. In P experiment, 40 ppm P_2O_5 with 200 ppm N and 200 ppm K_2O gave the best yield (74.8 t/ha). In K experiment, the highest yield (81.2 t/ha) was obtained in K_2O at 160 ppm with 200 ppm N and 70 ppm P_2O_5. First level of P gave an optimum yield and thereafter higher P levels decreased the yield, whereas the second level of N or K gave the best yield and then the yield either remained the same or decreased with nutrient increment, respectively. However, further studies are underway to corroborate these results.