THE IMPORTANCE OF TEMPERATURE FOR GREENHOUSE CULTIVATION
One of the advantages of greenhouse cultivation is the control of climatic conditions to ensure better plant development.
Among the climatic factors that influence the crop and production is the temperature, which must be between 18-25 ºC for the plant to grow peoperly and bear fruit (see table with a summary of temperature requirements for different species). Below or above this optimum temperature, the plant cannot develop properly and the crop may not complete its normal biological cycle and may not reach its maximum yield potencial.
In addition, temperature is involved (together with other factors such as CO2, light, etc.) in certain functions such as the opening or closing of the stomata, which are essential for the vital processes of photosynthesis, transpiration and respiration of the plant.
Under optimal conditions, these stomata, which are located on the underside of plant leaves, will be open to allow gas Exchange, allowing carbón dioxide to enter and oxygen to released.
If the temperature inside the greenhouse increases, the amount of water lost through transpiration also increases, and the stomata will close as a method of protection against excessive water loss. However, this method of protection can have a negative effect, as closed stomata restrict the entry of carbón dioxide, which is essential for photosynthesis.
In order not to lose water unnecessarily and to achieve the necessary gas Exchange, the plants must regulate the opening and closing of the stomata. Therefore, an optimum temperature must be achieved in order for the crop to develop well.
Depending on the effects they have on the crop, different types of temperature are distinguished:
Types of temperature:
- Minimum lethal temperature. Temperature below which damage to the plant occurs.
- Optimum temperature. The correct temperature for the plant to develop under ideal conditions.
- Biological maximum and mínimum temperatures. These indicate values above or below which, respectively, it is not possible for the plant to reach a certain vegetative stage, such as flowering, fruiting, etc.
- Maximum lethal temperature. The temperature above which damage to the plant occurs.