in the growth process of plants, after germination, the radicle first extends into the soil to form the main root, then the hypocotyl extends, and the cotyledon and the embryo are pushed out of the soil surface. This process is called germination. Because of cell division and the increase of the volume of new cells, the seedlings grow rapidly. At the same time, with the differentiation of cells, the differentiation of plant organs is more and more obvious, and finally grow into new plants, this process is called plant growth.
In this process, there is a process called growth big cycle, so what is growth big cycle? The answer will be revealed below.
What is the growth cycle of a plant? In the process of plant growth, the growth rate of cells, organs or the whole plant shows the law of slow fast slow. That is to say, the growth is slow at the beginning, then gradually accelerated, and then slowed down or even stopped after reaching the highest point. The three stages of plant growth together are called the grand period of growth. If time is taken as abscissa and growth amount is taken as ordinate, the growth of plant will be in "s" shape curve.
Why can the growth of organs show the birth growth cycle? This should be analyzed from the growth of cells. At the beginning of organ growth, most of the cells are in the cell division stage. Because the cell division is based on the increase of protoplast volume, the process of protoplast synthesis is slow, so the volume increase is slow. However, when the cells turn into elongation growth period, the volume of cells will increase rapidly due to the entry of water. However, when the cell elongation reaches the highest rate, it will slow down and finally stop.
Plant growth process
The growth of the whole plant is a "s" shaped growth curve, which is caused by complex reasons. It is mainly related to the size of photosynthetic area and the strength of life activities. In the early stage of growth, the photosynthetic area of seedlings is small, the root system is underdeveloped, and the growth rate is slow; in the middle stage, with the rapid expansion of the photosynthetic area of plants and the establishment of a large root system, the growth rate is obviously accelerated; in the later stage, the plants are gradually aging, the photosynthetic rate is slow, the growth of root system is slow, the growth is slow and even stops.
Generally speaking, plant growth is a process of irreversible increase in volume and weight. The volume and weight of the dead seed will increase as it absorbs water and expands, but it can still return to its original state after drying. This reversible increase in volume and weight cannot be called growth. Growth is usually accompanied by an increase in plant dry matter. However, it should be noted that during seed germination, the fresh weight and volume of the seeds increase obviously due to the absorption of a large amount of water, but before the formation of green leaves, the dry weight of the seeds decreases due to the consumption of a large amount of organic matter by respiration. At this time, the growth of protoplasm and the formation of new cells in the embryo are still growth phenomena. Therefore, the above definition of growth refers to most and relatively speaking.
How to use the growth cycle of growing plants? According to the law of growth cycle, corresponding measures can be taken to promote or inhibit the growth of organs and even the whole plant. For example, to promote the growth of rice and wheat plants, it is necessary to ensure sufficient water and fertilizer supply at the beginning of the middle period, so that the rapid growth can not be achieved later; for example, to prevent wheat lodging, it is necessary to affect the growth of wheat ears later before ear differentiation.
Plant growth can be expressed by fresh weight, dry weight, length, area and diameter of plant organs. While the growth volume is the amount of growth accumulation, that is, the actual amount of plant materials at the time of measurement, which is equivalent to the appearance of plants. Growth rate refers to the speed of growth, which is equivalent to the growth potential of plants, with absolute growth rate and relative growth rate. The former refers to the absolute growth amount per unit time, such as the number of fruit diameter per day; the latter refers to the percentage of the growth amount per unit time and the original plant amount, for example, the weight of each plant in a certain growth period is 10g, with a daily gain of 1g, with a relative growth rate of 10%; the weight of each plant in another growth period is 50g, with a daily gain of 2.5G, but the relative growth rate is only 5%. This calculation is easy to compare the actual effect of some agricultural measures on crop growth in different periods or different plots, and has practical significance.
How to make use of the large period of plant growth