Greenhouses are basically nothing but a special type of installation, which is prepared to suit the climatic and environmental conditions necessary for the growth of each type of plant and during any season, and this can only be done by adjusting the amounts of air, solar radiation, lighting and other elements. Different environmental and weather.
Environmental factors important to crop growth
The following is an explanation of the most important of those environmental elements that the farmer needs to follow up and work on adjusting according to the type of plant he wants to grow:
Percentage of light indoors
- Visible light (red or blue) is the main source of energy for plant photosynthesis.
- Sunlight, carbon dioxide, and water are the elements on which this process is based.
- For greenhouse crops. They can be classified into sun plants and shade plants.
- Sun plants are plants that are able to grow under strong solar radiation, while shade plants can wilt if exposed to high levels of radiation.
Temperatures affect the amount of production
- Temperature affects all physiological processes within a plant, including absorption, respiration, photosynthesis, etc.
- There is a variation in the temperatures required for each of these processes.
- eg; The plant needs high temperatures to complete the process of respiration compared to the temperatures required for photosynthesis.
- in general; Greenhouse crops grow at a temperature of 28: 20 ° C in the daytime, and 20: 17 ° C at night.
- Of course, talking about air as one of the basic elements in a greenhouse environment means referring to the most important air gases that have a strong environmental impact on plants.
- Primarily carbon dioxide and oxygen, which are necessary for the respiration process.
- CO2 is usually present in a limited amount inside hermetically sealed greenhouses, reaching 400ppm before sunrise.
- Then this rate decreases after sunrise, only reaching 150 parts; This is due to the consumption of large amounts of it during photosynthesis.
- The tight closing of greenhouses during the winter also results in a significant carbon dioxide deficiency, affecting the plant’s ability to produce its own food.
- In this case, mixing the air outside the plant cover with the air inside is a partial solution to this problem.
- CO2 can also be added inside the greenhouse by igniting propane or kerosene compounds using special devices.
- The optimal concentration of carbon dioxide inside a greenhouse is 300ppm.
- The optimum growth of greenhouse plants occurs at a humidity of 80:25%.
- Too low a home’s humidity results in significantly higher evaporation rates.->
- Also, high humidity inside greenhouses usually leads to the emergence of fungal diseases.
Air velocity inside the greenhouse
- As for air velocity; It affects some of the aforementioned environmental factors..
- For example, air velocity affects the rates of evaporation and transpiration in plant leaves.
- It also affects the rates of heat transfer between plant leaves and the air around them.
This is in addition to some pollutants that farmers need to prevent inside the greenhouses, including oxides, ammonia and all pesticides; As exposure to high levels of these pollutants for long periods of time (7 hours or more) would cause significant damage to the plant, and the solution here is to quickly work on aerating the greenhouse.