The growth and development of plants, including rooting and germination, growth, flowering, fruiting, etc., are not only controlled by genetic factors, but also regulated by plant hormones.
Plant hormones refer to some small amounts of organic substances secreted by various organs in the plant body, also known as endogenous hormones, which are formed from specific organs and transported to other parts to play a physiological role. At present, it has been found that there are six categories of plant hormones that regulate plant growth and development: auxins, gibberellins, ethylene, cytoses, abscisic acids and brassinolides.
Let's start with the answer to the titleAuxin can promote plant germination under the right concentration conditions. But auxin also has its peculiarities, and I will introduce auxin in detail below.
Auxin is the earliest growth regulator used in agriculture. Auxin is a hormone produced by the cell region with ** and enlarged activity that regulates the speed and direction of plant growth.
Auxin is a class of endogenous hormones containing an unsaturated aromatic ring and a side chain of acetic acid, abbreviated as IAA. 4-chloro-IAA, 5-hydroxy-IAA, naphthalene acetic acid (NAA), indole butyric acid, etc. are auxinoids. Therefore, it is customary to use indoleacetic acid as a synonym for auxin.
The main effect is to relax the plant cell wall, so that the cell growth is elongated, and in many plants, it can also increase the synthesis of RNA and protein. Regulates plant growth, especially canA class of hormones that stimulates the longitudinal growth of cells in the stem and inhibits the lateral growth of cells in the root. It can affect the phototropic and back-to-ground growth of the stem.
The action of auxin is manifested as a twofold:It can both promote and inhibit growth；It can both induce germination and inhibit germination;It can not only prevent falling flowers and fruits, but also thin flowers and fruits. This is related to the sensitivity of auxin concentrations to different parts of the plant.
1. Promoting effect:
1. Nucleus**, longitudinal elongation of cells
2. Parthenogenesis and ovary wall growth
3. Differentiation of vascular bundles
4. Leaf enlargement and formation of lateral roots
5. Growth of seeds and fruits, wound healing
6. Top advantages, etc.
2. Inhibition effect:
1. Shedding of flowers
2. Fruit shedding, young leaf shedding, and lateral branch growth
3. The effect of auxin on plant growth, such as the formation of tuber roots, is related to the concentration of auxin, the type of plant and the organ (root, stem, bud, etc.) of the plant.
3. In general:Low concentrations can promote growth, and high concentrations can inhibit growth and even cause plant death. Dicotyledons are more sensitive to auxin than monocots;Vegetative organs are more sensitive than *** organs;Roots are more sensitive than shoots, buds are more sensitive than stems, etc.
Auxin has been developed from the initial discovery of indoleacetic acid to now have dozens of substances with similar structures and functions, and synthetic hormone analogues are widely used in production. Its main functions are:
1. Promote the rooting of cuttings and improve the survival rate of cuttings
2. Promote fruit development, improve the fruiting rate, and obtain seedless fruits
3. Prevent falling flowers and fruits, and improve the fruiting rate;
4. Field weeding, using the difference in auxin concentration between monocots and dicots, to remove one of the weeds with high concentration of auxin.
Auxin is the earliest growth regulator used in agriculture. At present, the most widely used in production are indole butyric acid, naphthalene acetic acid, 2,4-d, etc., which are insoluble in water and easily soluble in organic solvents such as alcohols, ketones, ethers, etc. The main physiological functions of auxins are to promote the growth of plant organs, prevent organ shedding, promote fruit set, and induce flower bud differentiation. In horticultural plants, it is mainly used for cuttings and rooting, preventing flower and fruit fall, promoting fruit setting, controlling gender differentiation, changing the angle of branches, and promoting pineapple flowering.