Effects of different irrigation programs and nitrogen levels on nitrogen concentration, uptake and utilisation in processing tomatoes (Lycopersicum esculentum)

A study was conducted to investigate the effect of different irrigation programs and nitrogen (N) levels on N concentration, uptake and utilisation by the processing tomato (Lycopersicum esculentum). The amount of water used was determined based on a screened class-A pan. Irrigation treatments consisted of 2 different irrigation intervals (I5, 5 days; I10, 10 days) and 3 plant-pan coefficients (Kcp0.50, 0.50; Kcp0.75, 0.75; Kcp1.00, 1.00). Nitrogen treatments consisted of 3 N levels (N0, 0 kg/ha; N80, 80 kg/ha; N160, 160 kg/ha). The irrigation interval, plant-pan coefficient and N fertiliser rate affected all parameters examined; however, the N fertiliser rate had the greatest impact. Nitrogen applications increased N concentrations in the leaf, tomato and vegetative biomass. Plant total N uptake and benefit rate from fertiliser was highest with the N160, I10 and Kcp0.75 and Kcp1.00 treatments. Results show that the N160, I10 and Kcp0.75 treatments can be used for increasing plant N uptake and the benefit rate from fertiliser.