Improvement of greenhouse design and climate control in mediterranean conditions

The Mediterranean Region is one of the most important areas of the world in terms of protected cultivation. Turkey, with its increasing greenhouse area, is one of the representative countries of the region. Thanks to the mild winter climatic conditions, cultivation of vegetables under simple structures is possible. However, due to the changing concerns and demands on product quality and increasing competition in the market, there is a need to increase productivity. The aim of this study was to evaluate and suggest practical and economic improvements of both greenhouse structure and management, for both low tech and high tech greenhouses, in two different climatic zones of Turkey. Locally collected data were used to validate an existing greenhouse design tool, to predict greenhouse climate and tomato yield at given local climate conditions. Thereafter, alternative greenhouse designs and climate control strategies were simulated and evaluated. The results show that ventilation area should be at least 17% in all cases if insect net is not used. Among active climate management means: heating is worthwhile and temperature should not be less than 15oC for high tech greenhouses and CO2 enrichment (albeit with a limited capacity) should be considered. It can be concluded that such a combined climate-yield model, by quantifying the effect on yield of greenhouse improvements, can be used as an analysis tool for estimating the profitability of an investment.