NitroHealthy 2

The excessive use of nitrogen fertilisers on crops has caused the nitrogen (N) input to surpass crop demand for it, leading to nitrogen enrichment of the soil, mainly in nitrate form. That results in a nutritional imbalance in the soil that promotes N loss and influences the internal nitrate content of crops, especially leafy vegetable species. Vegetables accumulate large amounts of that anion in their leaves and they are the primary source for ingesting nitrates in the human diet. The potential health risk associated with nitrate ingestion has led European Union member states to regulate the limits for nitrate content in vegetables. Nevertheless, despite the advances made in agricultural best-practices and their strict application to reduce the presence of nitrate in leafy vegetables (lettuce and spinach) in certain regions of the European Union it is not possible to permanently achieve nitrate content lower than the current maximum limits. Consequently, the primary goal of this project is to find alternative nitrogen fertilisers for vegetable crops that are not nitric, because it is a key step for lowering nitrate consumption in the human diet.

Thus studying the use of nitrogen sources alternative to nitrate has become a high priority for the S3 “Food Chain” sector in Navarre (healthy food and food safety).

Another goal of the project is to gain knowledge about the bioactive compounds of the food obtained using the aforementioned fertilising alternatives that can provide essential information for producing food that is “high quality, healthy, natural, pleasurable and convenient”.

The primary conclusions of the project are the following.

1) Under controlled conditions, applying osmotic agents that compete with nitrate as an osmoregulator may decrease nitrate content in tissue (preliminary results). That alternative would have to be used with real vegetable crops under different growing systems (conventional soil and soil-less systems) to verify its effectiveness.

2) Under controlled conditions (growth chamber) ammonia use may be an alternative to nitrate fertiliser for reducing foliar nitrate content, as long as it is constantly accompanied by other compounds that regulate ammonia absorption and promote growth that counteract the negative effect of exclusive ammonia nutrition, providing vegetables with “zero” nitrate levels in tissue. To test that potential fertiliser alternative it will be necessary to use it in soil-less vegetable growing systems. And if it is successful it would make it possible for plants to regulate their physiological mechanisms on their own and palliate the performance reduction under ammonia nutrition conditions.

3) The study of the genetic response of the ammonia nutrition alternative accompanied by an ammonia absorption regulator under controlled conditions makes it possible to discover potential genetic and metabolic targets that could be acted upon to improve the efficiency of using different nitrogen forms and control the nitrate content in vegetables.

4) Compounds with antioxidant capabilities (mostly flavonoids) characteristically or potentially associated by different nitrogen sources were identified. That result is highly interesting for doing studies into the prevalence of that kind of compounds in the body after eating vegetables grown with certain nitrogen sources and their potential benefit for consumer’s health.