From the perspective of agricultural practice, plant growth plays an absolute role in agricultural production. Plant growth is good, crop yield is high, and farmers' income is high. The people’s income level is high, and the economy of the entire country will go up. Plant growth includes these aspects: the development of special organs, the development of whole plants, and so on. Currently, scientists have identified 52 factors that affect plant growth. Such as soil organic matter, soil moisture, root depth, temperature, humidity, illuminance, wind speed and so on. Below we focus on the impact of the temperature and humidity on the plant.
Effect of temperature on plant growth
Plants can grow only within a certain temperature range. The effect of temperature on growth is comprehensive. It can affect the growth of plants by affecting the metabolic processes such as photosynthesis, respiration, and transpiration, as well as the metabolic processes that affect the synthesis and transportation of organic matter. It can also directly affect soil temperature and temperature. It affects the growth of plants by affecting the absorption and transport of water and fertilizer. Since the activities of enzymes involved in metabolic activities have different performances at different temperatures, the effects of temperature on plant growth also have the lowest, optimum and maximum temperature three basis points. Plants can only grow at the lowest temperature and the highest temperature range. Although the optimum temperature for growth refers to the fastest growing temperature, this is not the most robust temperature for plant growth. Because at the optimum temperature, the organic matter in the plant is consumed too much, the plant grows slender and weak. Therefore, the cultivation of robust plants in production practice often requires temperatures below the optimum temperature, which is called the optimum temperature for coordination.
Different plants grow at different temperatures at three base points. This is related to the climatic conditions of the plant's origin. Native to tropical or subtropical plants, the temperature is three high, respectively
The three base points of the same plant also vary with organ and growth period. Generally, the root growth temperature is three base points lower than the bud. For example, the minimum temperature at which apple roots grow is
    The experimental data of the artificial climate chamber prove that the plant has the best vegetative growth during the period with high temperature and low temperature at night. Such as tomato plants at day temperature
The reason that the higher the day temperature is higher and the lower night temperature can promote the vegetative growth of plants, mainly because the daytime temperature is higher, which is beneficial to the increase of photosynthetic rate under strong light, and provides sufficient material for growth; the night temperature is lowered, and the respiration can be reduced. Consumption of organic matter. In addition, the lower night temperature favors root growth and cytokinin synthesis, thus also increasing the growth rate of the whole plant. In greenhouse or greenhouse cultivation, it is necessary to pay attention to changing the temperature of day and night, so that the effects of water, minerals, light, temperature and other factors on plant growth under the natural conditions are cross-cutting and comprehensive effects. First, there are interactions between environmental factors. For example, rainy days, dim light, temperature drop, increased soil moisture, and poor soil ventilation can occur in a chain, affecting plant growth. Secondly, each environmental factor acts on the plant body and is closely related to life activities, and they also affect each other. For example, light promotes photosynthesis, photosynthesis affects transpiration, and transpiration affects water supply. They are mutually reinforcing and mutually restrictive. In agricultural production, we must pay attention to the special effects of various environmental conditions on the individual physiological activities of growth, and we must use the idea of ​​splitting into two, grasp the main contradictions, and take reasonable measures to properly promote and inhibit the growth of plants. Achieve the purpose of cultivation.
Effect of humidity on plant growth
There are many factors affecting absolute humidity, depending on the source of water vapor, the ability to transport and maintain moisture in the air. Therefore, the factors affecting water vapor supply, such as precipitation, the presence of water, the level of soil moisture, and evaporation conditions, etc., affect the conditions of water vapor transport such as wind, vertical airflow, etc., as well as conditions that affect the ability of air to maintain water vapor, such as temperature, etc., may affect Absolute humidity. Generally, tropical ocean air masses have higher absolute humidity than polar ocean air masses; at the same latitude, areas affected by marine air masses have higher humidity than those controlled by continental air masses. The absolute humidity during the year is higher than the dry season. The change of absolute humidity in one day is the largest in the coastal area and autumn and winter, the smallest in the morning, and the unimodal change. For other areas, it is mostly bimodal , and the two high points appear at 9 to 10 and the day. Before and after, two lows appeared before sunrise and after noon. The vertical distribution of the absolute humidity of the air decreases as the height increases.
The relative humidity is determined by the absolute humidity on the one hand and the air temperature on the other hand. In cold regions and seasons, the humidity of the air is easily saturated , and the relative humidity may be higher in the case where the absolute humidity or the vapor pressure is not too high. Under the same absolute humidity conditions, the relative humidity in warm regions and seasons tends to be low. The general trend of the annual average relative humidity distribution in China is decreasing from the southeast to the northwest, and the mountains are higher than the plains. The annual change of relative humidity is generally higher in the inland dry area than in the summer; the lowest in spring and north in north China and northeast in winter; the annual change in Jiangnan is smaller.
Relative humidity or saturation difference of air is one of the important factors affecting plant water absorption and transpiration. When the relative humidity is small (the saturation difference is large), if the soil moisture is sufficient, the plant transpiration is more vigorous and the plant grows better. If the air humidity is saturated for a long time, the plant growth will be inhibited, resulting in lower grain filling rate, increased cotton buds, increased cotton vitality and affecting cotton harvest quality. If the relative humidity is too small, it will aggravate the soil drought or cause atmospheric drought. Especially under the condition of high temperature and lack of soil moisture, the water balance of the plant will be destroyed , and the water will not be able to make enough , which will hinder the growth and reduce production. The relative humidity and saturation difference can restrict the time of flower anther cracking, pollen scatter and germination of some plants, thus affecting the pollination and fertilization of plants. Humidity is also closely related to the occurrence of crop pests and diseases. In the environment where the wheat larvae are humid, the cotton aphid and red spider are suitable for living in a low humidity environment. Humidity is high , which is easy to cause a variety of diseases such as wheat rust. For domestic animals, generally at a relative humidity of 50 to 70% is appropriate, humidity is too low can lead to mucous membranes, skin, chapped A hoof infections caused by germs, etc., humidity is too high, easily causing bacteria and parasites breeding. The combination of high humidity and high temperature will inhibit the evaporation and heat dissipation of the carcass, which will easily cause heat accumulation in the livestock; the combination of high humidity and low temperature will increase the thermal conductivity of the air and easily increase the heat loss of the livestock and cause disease.
Effect of illuminance on plant growth
Effects of illuminance on the growth and development of medicinal plants
Light is the source of energy for photosynthesis in plants. Photosynthesis is mainly done by relying on the chlorophyll of plants. In plant ecology, it is usually divided into three categories: positive plants, negative plants and shade-tolerant plants according to the different requirements of plants for light:
A positive plant is one that grows strong in a strong light environment and grows poorly under concealed and low light conditions. Such as licorice, Atractylodes, Peony, Dihuang, Cassia, mint and so on.
Negative plants are plants that grow well under weaker light conditions than under strong light conditions. But this is not to say that the weaker the requirement for the negative plant is, the better, because when the light is too weak to reach the compensation point of the negative plant, it will not grow normally, so the negative plant requires weaker light. It is also only relative to positive plants. Negative plants grow in wet, shady areas or are born in dense forests, such as Liancao, ginseng, Araceae, and berberine.
A shade-tolerant plant is a plant that is between two classes. These plants grow best under full sunlight, but they can tolerate moderate concealment or require lighter shade during birth. Such as ginseng, huangjing, cinnamon, coltsfoot and so on.
However, the same plant has different requirements for light at different stages of development. Woody plants such as Magnolia, Eucommia, etc., need to be shaded at the seedling stage, afraid of glare. When the ginseng seedlings are overcast, the adult plants are Xiyang. Although Coptis is a negative plant, it has different stages of growth and different degrees of tolerance. The seedling stage is the most resistant to yin, but in the fourth year after planting, the cloak can be removed and grown under strong light, which is good for root growth. Under normal circumstances, plants need more nutrients during flowering and fruiting stages or storage organs such as tubers, and the requirements for light are higher. Understanding the ecological types of plants on illuminance is very important in the rational cultivation of medicinal plants, as well as interplanting, introduction and domestication.
Since we understand that temperature and humidity and illuminance have a great impact on plants, it is necessary to know the temperature, humidity and illuminance of plant growth. There are already manufacturers on the market that are capable of measuring one parameter or multiple parameters. For example, the temperature and humidity recorder is two parameters for measuring temperature and humidity; there are three parameters, such as temperature and humidity three-parameter recorder (for details, please refer to China Agricultural Instrument Network http:// ). Of course, there are also instruments that can only measure a single parameter, such as a temperature recorder, which can only measure the temperature of the environment. Therefore, if you want to understand the growth of plants, it is necessary to have a temperature and humidity photometer, and this instrument can measure a variety of parameters, so that you can get environmental data quickly and easily in practical applications.
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