Environmental principles and control technology of modern greenhouse

Environmental principles and control technology of modern greenhouse

All organisms need a suitable environment for growth, including light, temperature, moisture, soil, atmosphere, etc. Each environmental factor is interlinked, mutually reinforcing and mutually constraining, and their effects on crops change as the growth and development stages go on.

1. Light control

The effect of photosynthesis is not only determined by the wavelength of light and light intensity, but also by the accumulated time of light and light period, so the research and control of light is especially important.

Light control mainly has light intensity control and light cycle control in two ways, in the control, the use of light intensity meter and timer and other basic sensor control components, real-time detection of dynamic light intensity changes, with the clock control, so as to complete the control of light. Both shading and artificial light supplementation are often used.

Greenhouse shading is the use of materials with a certain degree of light transmission to block part of the excess light, so as to ensure the normal growth of greenhouse crops need light, but also to prevent the excess solar radiation energy gathered in the greenhouse, resulting in high indoor temperatures. Greenhouse shading is divided into outdoor shading and indoor shading.

In winter and spring, when light hours are short and light is weak, light becomes the main limiting factor for crop growth and development. Artificial light supplementation means that according to the light intensity, period and time required for crop growth and development, different artificial light sources are used to supplement the light for crops.

2 Temperature control technology

Temperature is the environmental factor that crops depend on for survival and growth. Too high or too low temperature can cause fatal disasters to crops. Temperature control is the most perfect control means in modern greenhouse environmental factors. Temperature control Baum retreat room temperature management and a variety of insulation, heating, cooling measures.

2.1 Greenhouse insulation

Greenhouse insulation can effectively reduce greenhouse heat loss, improve greenhouse temperature and save energy.

At present, more insulation measures used are mainly.

1. additional insulation material outside the greenhouse.

2. reducing the height of the greenhouse and reducing the exterior area of the greenhouse.

3. changing the form of greenhouse structure to increase the amount of light.

4. setting internal insulation curtain; improving covering materials.

5. choosing light-transmitting covering materials with poor thermal conductivity.

6. Improve the installation method of covering materials to improve the airtightness of greenhouse, etc.

2.2 Greenhouse heating

Greenhouse heating system is generally composed of heat source, indoor heat dissipation equipment and heat medium delivery system. Nowadays, the common heating methods in greenhouses mainly include hot water heating, steam heating, hot air heating, electric heating and radiation heating.

The choice of heating scheme should be based on the local climate characteristics, the heating load of greenhouse, the supply of local fuel and investment management level, etc.

2.3 Greenhouse cooling

Greenhouse cooling mainly has ventilation cooling, shading cooling and evaporation cooling. Ventilation has natural ventilation and forced ventilation; shading has indoor shading system and outdoor shading system and shading method of painting on the surface of greenhouse; evaporative cooling mainly has mist cooling and wet curtain cooling.