Action mechanism of plant antifreeze

Introduction of plant frost resistance

When the atmospheric temperature drops below zero degrees Celsius, some plants freeze to death because they can't resist the cold, while others can stand proudly in the ice and snow, full of vitality. This is because there are significant differences in frost resistance of different plants.

Biofilm system in plant cells is closely related to plant frost resistance; When plants encounter low temperature, the biofilm will change phase, that is, from liquid crystal phase to gel state, and the membrane structure will be destroyed. In this way, non-lipid "caves" with high permeability will be formed on the plasma membrane, which will become channels for many electrolytes to enter and exit freely, and a large amount of sol in the cytoplasm will be discharged, which will eventually lead to plant death. Therefore, frost-resistant plants must have the following characteristics.

First, when the temperature decreases, it must be able to maintain the normal liquid crystal phase of the biofilm in the body; Secondly, it has the stability of membrane structure, which is positively related to the cold resistance of plant varieties; Third, it can avoid freezing in cells and prevent ice crystals from damaging cell membranes; Fourth, the water inside the cell will freeze outside the cell, which will also cause some harm. This is because freezing dehydration will cause cell drought, denature protein, and at the same time, it will also cause cell contraction, collapse and damage plasma membrane. Therefore, it must also have the properties of freezing and dehydration. However, the frost resistance of various plants to the above requirements is different. Some plants only have one or two of them, and some even don't have them at all, so some varieties are afraid of cold and some varieties are frost-resistant. Such as tomatoes, cucumbers, bananas and pineapples. , often suffer from cold damage below 10 degrees Celsius, while pine, cypress, bamboo, spruce and so on. Can survive normally in the ice and snow environment.

To combat cold damage and prevent the harm of low temperature to crops, we should mainly start from two aspects: improving the frost resistance of crops and preventing the influence of adverse climatic factors on crops. After cold-resistant exercise, a series of physiological changes of plants can be artificially promoted, thus increasing their cold resistance.

In the field, cold-resistant exercise goes through two stages: first, let plants carry out vigorous photosynthesis in sunny weather before winter, and accumulate more "protective substances", that is, nutrients (sugar and amino acids, etc.). ) and increase the content of unsaturated fatty acids in membrane lipids, which is very important to prevent biofilm phase change and stabilize membrane structure. Secondly, under the condition of stable low temperature in late autumn, field irrigation is controlled, so that plants can undergo the normal dehydration process of intercellular space and the normal change of protoplasm colloid state, and the free water content in plant tissues is reduced, thus reducing the possibility of tissue freezing. After the above two aspects of exercise, the reaction of cell protoplasm to adverse conditions will become slow, and the frost resistance will naturally be significantly improved.

The frost resistance of crops is closely related to quality characteristics and cultivation measures. Crops sown in autumn and varieties with strong winterness should be sown early in time, and strong seedlings should be cultivated by using favorable conditions such as crisp autumn air and strong sunshine to enhance their cold resistance and promote their safe wintering. Varieties with strong springiness should not be sown too early, otherwise the vegetative growth will be too vigorous before winter, and the cold resistance preparation will be insufficient, which will easily lead to seedling death. In addition, suitable sowing depth, ridge cultivation, application of organic fertilizer and phosphorus and potassium fertilizer can increase the cold resistance of crops.

The weather changes dramatically in early spring. When winter wheat turns green, the effect of cold-resistant exercise gradually disappears, and it is extremely vulnerable to freezing in case of late frost. In view of this situation, measures such as smoking and irrigation can be taken, and greenhouse, hotbed, sunshine bed, plastic film and soil heat preservation agent can be used to overcome the unfavorable factors of low temperature and sow early. In addition, windproof and mulch can be set up to change the microclimate of crop growth and avoid the harm of low temperature. Freeze protection and hormone control can also be used to enhance the frost resistance of plants. For example, if sucrose, dimethyl sulfone or polyethylene glycol are added into the microscopic sections of plant buds and tissues, or in the ice-cold medium of cell suspension culture, the frost resistance of plants will be significantly improved. This substance is called antifreeze.

Recently, it was found from the study of aseptic seedlings such as potatoes that the cold resistance induced by adding plant hormone abscisic acid (ABA) to the culture medium at room temperature for half a month was similar to that induced by low temperature exercise at 2℃. At present, this method has been used in scientific research and production practice to increase the frost resistance of grape, citrus and other fruit trees.

Plant antifreeze (or tree antifreeze and garden plant antifreeze) The antifreeze used for garden plants is generally called: plant antifreeze, garden plant antifreeze, tree antifreeze, seedling antifreeze or antifreeze.

With the acceleration of urbanization and the development of urban landscape industry, it also promotes the development of landscape plant maintenance products. At present, plant antifreeze is mostly aimed at garden plants, with many brands and no unified standard. The general ingredients are hormones and related ingredients that increase the sugar and amino acid content of plants.