To Stop Nitrogen Overdose in Soilless Tomato Crop: A Way to Promote Fruit Quality without Affecting Fruit Yield

Abstract

Precision horticulture is fundamental to ensure high quality production with a minimalenvironmental footprint. It offers the possibility to manage climatic and fertilization inputs closerto the plant needs. In practice, there is a tendency to over‐fertilize, as nitrogen limitation candecrease photosynthesis and consequently fruit yield, but also because nutrient recycling does notlead to any substantial costs increase, thus ignoring the influence of nitrogen input on the balancebetween growth and metabolism. Nitrogen recommendation for tomato greenhouse production onrockwool is 16mM, even it is well established that only 50% of nitrogen amount is really absorbedby plants. This study compares the usual practice (16 mM) to a nitrogen supply to meet plant’sneeds (5 mM). We analyzed plant growth and development, yield, leaf photosynthetic activity andfruit quality (sugars, acids, vitamin C,) over the entire crop period (December to October).Over‐fertilization favoured the accumulation of nitrogen in leaves and stem but yield, leafphotosynthetic activity and plant architecture were not significantly improved. In addition, itdecreased the quality of the tomatoes as the sugar:acid ratio decreased dramatically in the pericarp,whereas the locular gel composition remained similar. A reduction of the nitrogen supply is onesolution to improve tomato quality without any reduction of yield in greenhouse. These data haveto be incorporated in tomato fertigation management to define a new standard based on overallquality of tomato fruit and low environmental footprint.

Increasing Sustainability of Growing Media Constituents and Stand-Alone Substrates in Soilless Culture Systems

“…However, in practice, soilless culture vegetables are usually over-fertilized, and an excessive synthetic N fertilizer is applied to ensure that no nutrient deficiency occurs. Indeed, as Truffault et al [154] reported, over-fertilized tomatoes provided an accumulation of N in leaves and stems. However, yield, leaf photosynthetic activity, and plant architecture were not significantly improved.…”

“…However, yield, leaf photosynthetic activity, and plant architecture were not significantly improved. In addition, the quality of tomato fruits decreased in terms of their sugar:acid ratio and dramatically decreased in the pericarp, whereas the locular gel composition remained similar [154]. Therefore, the reduction of fertilizer used, first and foremost the N fertilizer, is the first appropriate and sustainable step that should be undertaken.…”

Opportunities of Reduced Nitrogen Supply for Productivity, Taste, Valuable Compounds and Storage Life of Cocktail Tomato

“…These conclusions apply to tomato plants grown in soil, while soilless cultivation of tomato plants seems to increase their sensitivity towards reduced N supply as several studies report decreased photosynthetic activity [2], plant biomass [14,15,46,60] and fruit mineral contents [7]. However, it is possible to overcome N deficiency and ensure high fruit yields of soilless-grown tomato plants by supplying N levels larger than 4.5 mmol L −1 [2,15,19].…”

“…They showed higher TEAC values probably due to the higher contents of ascorbic acid (Table 5). Other studies showed that reductions in the N supply up to one third of the optimal level often had no effect on the vitamin C content of the tomato fruits [2,7,15,20,29,32]. Moreover, other results suggest that the antioxidative capacity of tomato fruits is little affected by the N supply [20,50,51].…”

“…The supply of N is therefore decisive for the quality of food crops; the application of fertilizer in crop cultivation is essential for profitable plant production. In particular, the intensive cultivation of vegetable crops involves high amounts of N fertilizer (as well as other nutrients) and often results in an excessive N supply [2]. This implies that vegetable production often does not meet the requirements of environmental legislations for good ecological water status (e.g., the EU Nitrates Directive or the EU Water Framework Directive).…”