Growth, yield and postharvest quality of tomato (Solanum lycopersicum Mill.) as influenced by different rates of nitrogen fertilizer

There is no available information on optimal nitrogen (N) fertiliser rates to maximise tomato production in the Philippines hence excessive N application is a problem. This research was conducted to determine the optimum rate of N to enhance production of different tomato cultivars. The experiment was a randomized complete block factorial design evaluating a range of N rates (72.8, 122.8, 172.8, 222.8, 272.8 and 322.8 kg N ha(-1)) in combination with two cultivars ('Harabas Rescuer 746' and 'AVTO1173') and replicated four times. On the 2(nd) crop, an N rate of 222.8 kg ha(-1) produced the highest total plant dry matter yield (176 g plant(-1)), the largest and heaviest fruits (mean 49.6 g) and the lowest weight loss. The highest fruit yields were also recorded at an N rate of 222.8 kg ha(-1) for the first (14.4 t ha(-1)) and second (28.1 t ha(-1)) crops. 'AVTO1173' had the earliest flowering, a 47% higher dry matter value and produced the largest diameter fruit (5.33 cm in first crop and 4.9 cm in the second crop). 'AVTO1173' was less susceptible to diseases compared with 'Harabas Rescuer 746' and had less shrivelling in the 1st cropping cycle. It is recommended that nitrogen fertilization at 222.8 kg N ha(-1) should be used for producing high yields and good tomato fruit quality.