Nitrogen level effect on yield and quality of fertigated processing tomato in Southern Italy

Despite the importance of fertigation on improving yield, water, and fertilizer use efficiency, its management by the farmers is still rather empirical. Increasing the N-use efficiency (NUE) is a must to precisely satisfy crop requirements during its growth and development. However, there are not enough studies correlating the rhythms of growth and accumulation of nutrients in processing tomato in the Southern Italy environments. Four N levels (0, 100, 200 and 300 kg.ha(-1)) were applied through fertigation in order to evaluate the growth, N uptake, NUE, and yield of tomato. The fresh and dry weight of leaves, stems, and fruits were determined as well as the number of fruits and leaf area during the growth cycle. Leaves, stems, and fruits total N content was analysed at the early and late stage of fruit setting and at fruit ripening. At harvest, total and marketable yield were assessed. By applying 300 kg.ha(-1) of N, plants had higher dry mass yield (about 13.0 t.ha(-1)). Fresh matter, total, and marketable fruit yield increased from 0 to 100 and 200 kg.ha(-1) of N (6.6, 5.5, and 4.2 kg/plant, respectively), while with increasing levels the same variables showed a decreasing trend. A greater number of total and marketable fruits per plant (160 and 109, respectively) was yielded supplying 1 200 kg.ha(-1) of N. The crop N uptake linearly increased from the control (176 kg.ha(-1)) to the highest N dose (339 kg.ha(-1)); the lowest nitrogen use efficiency in terms of total aboveground dry mass (NUE-pt), or fruit dry mass (NUE-ft) was observed with 300 kg.ha(-1) of N.