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Use of greenhouse covering films with tailored UV-B transmission dose for growing "medicines" through plants: rocket salad case.

BACKGROUND
The effects of UV-B radiation on plants are well known and have recently been attracting a great deal of attention due to the production of a vast quantity of secondary metabolites which are highly beneficial substances for human health. Recent studies have demonstrated the possibility of exploiting UV-B radiation in order to induce metabolic changes in fruit, vegetables and herbs. The contribution of UV-B rays for inducing secondary plant metabolites is enhanced by new plastic films which, according to their optical properties, permit the necessary dosage of UV-B transmitted into the greenhouse so as to stimulate such metabolites without altering the harvest.


RESULTS
The main goal of the present paper is to demonstrate that by using a greenhouse plastic film with an appropriate transmittance of UV-B for rocket salad cultivation; it is possible to increase the nutraceutical elements, in comparison with the same grown in absence of such radiation. Tests were arranged comparing nutritional elements extracted from rocket salad grown under greenhouses covered with several plastic films differing in UV-B transmittance. We found that due to UV-B action rocket salad grown under plastic with 27% of UV-B transmittance, exhibited very high contents of luteolin and quercetin in comparison with rocket salad cultivated under film blocking UV-B radiation.


CONCLUSIONS
Our experimental results confirm the possibility of exploiting the correct percentage of UV-B radiation, through appropriate greenhouse plastic covers, in order to produce natural "medicines" via the plants and to satisfy an increasing consumer demand for natural health-promoting food products. This article is protected by copyright. All rights reserved.