Project start: 01.05.2011
Project end: 31.10.2014
Sponsor: European Commission

Beside the traditional cultivation of raspberry in open field, they are now increasingly grown under rain protection or in high tunnels to extend the cropping period. The main used plastics are standard polyethylene foils to cover rainshelters and tunnels. However, different materials are available nowadays which vary in their transparency for UV radiation or have shading properties. Raspberry leaves and berries are rich in in vitamin C and polyphenols. They are synthesized at biotic or abiotic stress and their antioxidant action protect the plants against oxidative stress by free radicals. Moreover, these bioactive compounds play a crucial role in the prevention of a wide range of human diseases. The use of high tunnels alters the growing conditions for raspberries by changes of the microenvironment, mainly temperature. Photosynthesis is one of the most temperature-sensitive factors controlling plant growth. Beside photosynthesis, heat stress is negatively associated with a lot of physiological activities. However, less is known about changes of photosynthesis, carbohydrate synthesis and accumulation of nutritional ingredients in raspberry fruits grown under plastic tunnels. Therefore, the impact of different environments (light intensity and – quality, temperature and rel. humidity) on photosynthesis of raspberry plants and their carbohydrate and polyphenol compounds will be studied in a comparative trial between cultivating them in open field or in high tunnel with shading or different UV transparency properties.