The project "Integration of sustainable technologies to reduce climate stress in greenhouse horticultural production in the Mediterranean area", carried out by the University of Almería, Ifapa, Imida and the Cajamar Foundation, has served to assess different growing conditions for bell peppers in greenhouses during the 2019/20 campaign. One of the conclusions is that the vertical evaporative system makes it possible to obtain significant improvements in the cultivation of this vegetable, increasing the commercial yield.
The Foundation reported that there has been an evaluation of two systems designed to improve the temperature and humidity of the greenhouse at the start of cultivation of summer plantations. This is a time of the year when the poor leaf development and the climate cause suboptimal conditions for greenhouse cultivation. Even though there are technological solutions on the market to mitigate this situation, they are expensive (evaporative panels, high pressure misting, etc.) or are far from adequate, since they make the crop wet (low pressure misting).
In the systems evaluated, an easily wettable fabric has been used that has facilitated the evaporation of water in the greenhouse without becoming a hindrance to the development of agricultural operations, or making the crop wet. This material has been installed in two different ways: vertically between the paired cultivation lines, and in the form of a double roof with a slope above the crops. In both cases, it has been moistened by means of conventional drip tape. Both treatments have been compared with a standard treatment in bell pepper crops planted in the first half of July and maintained until early February.
Although the double roof system had a larger evaporating surface and achieved a somewhat higher relative humidity than the vertical system, the latter has proven to be more practical, since it is much easier to install and does not affect the radiation transmissivity of the greenhouse. In fact, the double roof system considerably limits radiation and the only way to increase it was by removing the double roof.
Evaporative systems have clearly improved the vegetative development of pepper crops. At the end of the test, a significantly higher commercial production has been obtained with the vertical treatment compared to the control; 20% more, specifically. This has been a consequence of there being a greater number of fruits, since the average weight of these has not been affected.