Casar, CristinaMuñoz-Guerra, Luis M.Ordiales, ElenaLópez, JoaquinNunes, Carla2013-09-182013-09-182010http://hdl.handle.net/10400.1/2901Proceedings of the International Conference “Environmentally friendly and safe technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro,Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924Nitrogen management in plant nutrition is an agronomic and environmental key factor. Under soil conditions the main form of N available for the plant is nitrate. Nitrification inhibitors reduce the nitrification rate and increase the ammonium absorbed by the plant. This effect reduces the risk of groundwater pollution by nitrates. Nitrate may be dangerous for human health and can increase oxalate concentration and decrease vitamin C (vit C) content in vegetables. This paper presents the results of three field trials on tomato, spinach and broccoli, all of them for industrial processing (spinach and broccoli for frozen industry and tomato for tomato paste). In the three trials a conventional ammonium plus nitrate fertilization was compared with the application of ammonium plus nitrate plus nitrification inhibitor, using similar rates of N. All of the trials were conducted in Badajoz (Spain) during 2006 and 2007. In the spinach trial the ammonium increase (with the nitrification inhibitor) reduced nitrate and oxalate in leaves and increased vit C. Greater yields were obtained with mixed fertilization (nitrate plus ammonium plus nitrification inhibitor). In the Broccoli trial there was no differences in yields but using the nitrification inhibitor, a slightly increasing of vit C content was obtained. The trial performed with fertigated industrial tomato shown that the use of nitrification inhibitor increased yield on 8% and also increased the lycopene concentration (also colour a/b ratio) from 32 mg kg-1 (conventional fertilization) to 45 mg kg-1. These results presented shows that important nutritional parameters, as nitrates, oxalates, vit C or lycopene are influenced by the quantity and characteristics of the N fertilizer applied, and that a mixed nutrition nitrate plus ammonium with nitrification inhibitors, can increase vit C contents and reduce nitrates or oxalates.engBroccoliIndustrial tomatoNitrateNitrification inhibitorOxalateSpinachVitamin Cbook part