Impact of climate change on water and nitrogen use efficiencies of processing tomato cultivated in Italy

Tomato (Solanum lycopersicum L.) is a globally important vegetable recognized for its positive health benefits. As most of the vegetable production, tomato require significant amount of agronomic inputs. However, recent shifts in climate patterns in terms of timing and amount in rainfall, patterns in air temperature, and the associated extreme events have caused harm and disruption to the agricultural sector worldwide. The objective of this study was to: i) evaluate the ability of a crop simulation model to simulate yield and growth parameter of a processing tomato in South west Italy; ii) quantify the impacts of projected climate on business as usual agronomic practices; iii) understand the role of projected changes and increased CO2 on the water and nutrient efficiency. Field trials from an open field at Sele Valley (40°35′03.8″ N, 14°58′48.6″ E) (Salerno, South west Italy) during a two-year period (2004–2005) were used. Baseline climate data (1984–2018) were available and four contrasting projections were selected as function of their spread in terms of changes in growing season rainfall and temperature respect to the baseline. The crop model DSSAT (Decision Support System of Agrotechnology Transfer) was used for this study. The model was able to simulate tomato response to N fertilization with acceptable error levels respect to the ones reported in literature. The projected increase in air temperature and changes in rainfall caused a shortening ranging from 1.5 to 3 days in tomato phenology causing an overall 15 % reduction in tomato yield. To offset the negative impact of rainfall and temperature changes, additional irrigation water (from 85 to 110 mm) and nitrogen rate (from 20 to 30 kg N ha−1) is needed. However, the increase in irrigation water does not translate in significant yield increase and caused an increase in water and nitrogen use efficiency of less than 10 %.