Researchers from the University of Almería headed by Ignacio Fernández de las Nieves have studied the impact of shade nets on the nutritional value of organic tomatoes. They concluded that the nets contribute to the antioxidant activity of the fruits, mainly due to the increase in the level of flavonoids and phenylpropanoids.
The field study, carried out at the facilities of the Almeria-based company Biosol Portocarrero, is innovative not only because it compares the productivity of organic tomato cultivation under shade nets with the traditional method, but also because nuclear magnetic resonance (NMR) has been used to determine the composition of healthy compounds in the fruits.
During the study, a total of 144 organic tomato extracts of the Delyca variety were analyzed and grown under two different shade conditions. Tomatoes from each area were harvested weekly between May and July 2017, with 12 harvests in total.
The importance of the nutritional value
The results show that the total content of phenolic compounds, especially flavonoids and phenylpropanoids, increased through the use of shade nets. This explains the increase in antioxidant activity and thus the higher nutritional value of these tomatoes, compared to traditionally grown crops. There was also a reduction in the concentrations of lycopene carotenoids and beta carotene, compared to crops grown without shade nets.
This study is particularly interesting for the grower in terms of crop productivity. Organic tomatoes grown under shade nets that reduce light intensity by 50% saw the yield in terms of volume fall by 35%, with individual tomatoes being 4% smaller and 12% lighter.
The study has been published in the US Journal of Agriculture and Food Chemistry.