Effects of Se-enrichment on yield, fruit composition and ripening of tomato (Solanum lycopersicum) plants grown in hydroponics

Selenium appears to be effective in promoting plant development and delaying the onset of senescence. Besides the effects on the metabolism and physiology of different crops, controlled increases in Se concentrations enhance the health-related properties of the produce. To study the effects of selenium on fruit composition and ripening physiology, an experiment was carried out on tomato (Solanum lycopersicum) plants grown in hydroponics. Sodium selenate was added to the nutrient solution at a rate of 0 (control) and 1 mg Se L−1 . The selenium added to the nutrient solution was absorbed by the roots, and the Se concentration was higher in leaves than in fruits. The addition of Se did not significantly influence the cumulative yield of tomato plants, but a delay in the onset of fruit ripening was detected, and the harvesting of control plants began earlier than in Se-treated plants. The addition of Se did not significantly affect the qualitative parameters with the exception of -carotene content, which was lower in red ripe fruit treated with selenium. Since -carotene accumulation is a ripening-related event in tomato, the lower amount of this compound may be associated with a general delay of ripening. This is confirmed by the reduced biosynthetic rate of ethylene, observed in Se-treated tomatoes, which also showed a reduced rate in colour change. This thus confirmed that ripening-related processes, such as the degradation of chlorophyll and the synthesis of carotenoids, are affected by selenium - with potential benefits in terms of storage and shelf-life. Our results showed that 100 g of tomato hydroponically grown with a nutrient solution supplemented with Se provided a total of 58 g Se. Thus, the daily consumption of 100 g of enriched tomato does not lead to Se toxicity, but can even provide a rational Se supplementation. This suggests that the addition of Se in a nutrient solution is useful for producing tomatoes with greater beneficial properties for human health.