Lightweight Medterranean shelters make production possible before the normal season for field crops. Research has led in 3 directions:
The slope of the roof and orientation of greenhouse structure have been defined for optimal climatic conditions.
Progress has been made in development of the hydrotunnel to reduce the danger from spring frost. The use of large transparent plastic tubes filled with water and laid on the ground to either side of the plants to return at night the heat accumulated during the day is now widespread in Greece, and is providing good results.
The use of solarization to control soil fatigue seems to be an effective but temporary way of keeping down nematode populations.
Improvement of plant material:
The varieties grown in Mediterranean shelters have to produce regularly in an unfavourable environment (cold nights, very variable humidity). Greater use is being made of parthenocaropic varieties which can be harvested without fertilization. A good parthenocarpic genitor has been found.
Shelters require to be used to grow other crops, either in the event of glut or during the normal growth period. Many plant species have been tried and some are of great interest.
The project was set up to investigate methods of improving the quality and production of crops grown in plastic greenhouses in southern areas of Europe. Data on air exchange rates was recorded in traditional and improved greenhouses with natural ventilation. Forced ventilation was examined as a means of reducing fungal risk. Passive solar heating systems were tested for cold protection and heating of greenhouses in mild winter Mediterranean areas and an economic analysis made. The behaviour of plants under various stress conditions was evaluated and models for transpiration and photosynthesis have been prepared. Soilless culture of tomato was used to determine the actual uptake of the main elements (nitrogen, phosphorus, potassium, calcium, magnesium) and showed that reduction of fertilizer by 50% is possible, without change in yield. Several substrates were evaluated for physical effects and productivity. New species of ornamental plants and vegetables are being tested in the greenhouse.
The total area of plastic greenhouses in southern EC is estimated at 50 000 ha. Presently this activity is facing two major problems, the need for a crop diversification, and the low quality of the products in relation to environmental stress, which constrains quality and production efficiency.
The project tackles these problems through integrated multidisciplinary actions :
I. Greenhouse engineering and ecophysiology for the control and characterization of stress conditions and effects (climatic, water, osmotic) by means of passive and dynamic techniques of ventilation, shading, cold protection.
II. Breeding to select and evaluate plant material of tomato for low temperature fruit-setting and osmotic stress resistance.
III. Growing techniques for new introduction of crops and cultivars.
38080 La Laguna
06610 La Gaude
29750 Algarrobo Costa