Phosphorous acid products—This product contains phosphorous acid (H3PO3). As a potassium fertilizer, its water-soluble potassium content is about 26.0%; as a phosphate fertilizer, it has a higher phosphorus content than phosphoric acid, is easily hydrolyzed, and can be quickly absorbed by plants.
Phosphite has become very popular in recent years, so do you know what phosphite products are?
Phosphorous acid, an inorganic compound, is easily soluble in water and alcohol. Slowly oxidizes to orthophosphoric acid in air. It decomposes into phosphine and orthophosphoric acid at 180℃. Corrosive. Phosphorous acid is a dibasic acid with slightly stronger acidity than phosphoric acid. It has strong reducing properties and can easily reduce silver ions (Ag+) to metallic silver (Ag) and can reduce sulfuric acid to sulfur dioxide. Phosphorous acid is mainly used as a reducing agent and nylon whitening agent. It is also used as a raw material for phosphite, a pesticide intermediate and a raw material for organophosphorus water treatment chemicals.
Phosphite is an alkaline metal salt of phosphorous acid. It often contains cations such as potassium ions, sodium ions, and ammonium ions, as well as anions such as phosphate, hydrogen phosphate, and dihydrogen phosphate. In phosphorous acid fertilizers, Phosphorus in the phosphorous state has a valence of +3, while phosphorus in the phosphoric acid state has a valence of +5. Phosphorous acid (H3PO3) and phosphite fertilizers contain higher concentrations of P than traditional phosphoric acid (H3PO4) and phosphate fertilizers. Phosphorous acid Salt ions have one less “oxygen” than phosphate ions. This determines that phosphite can be quickly absorbed by the cell membranes of leaves and roots, and has faster mobility within the plant body.
Application and development of phosphorous acid
In most cases, phosphate compounds are considered to be the only form of phosphorus nutrition for plants. Because the oxidation of phosphite to phosphate takes a long time, the concept of using phosphite as a source of plant nutrient phosphorus is controversial. Many published research results have proven that phosphite can be absorbed by plant leaves and roots, but it is not utilized by plants as a phosphate fertilizer. On the contrary, phosphite has some side effects during the growth and metabolism of bentonite in phosphorus-deficient plants, inhibiting the reactions of typical plant molecules thereby further causing phosphorus deficiency and causing deleterious effects in phosphorus-starved rather than phosphorus-sufficient plants.
Of course, some researchers believe that the use of phosphite has certain effects on promoting plant nutritional balance, accelerating maturity, improving fruit quality and post-harvest shelf life, and can be used as a source of plant nutrition.
Until Lovatt, a professor of plant pathology at the University of California, Davis, sprayed potassium phosphite, citrus that was deficient in phosphorus could restore the plant’s biochemical reactions and resume normal growth. In other words, phosphorous acid could replace phosphoric acid. Can be absorbed and utilized.
Promote flowers and fruits, increase production and income
Phosphites were initially used in agriculture for their effectiveness in plant disease control rather than plant nutrition. At present, phosphite has been widely used as a fungicide in foreign countries. It is mainly used on potatoes to prevent potato tuber rot and diseases caused by Oomycetes. By spraying phosphorous acid on the leaves, the average susceptibility to potato late blight in potato tubers and the rot degree of potato tubers are significantly lower than those without spraying phosphorous acid. It is also very effective in preventing potato tuber pink rot and late blight. There have been many studies on crops such as wheat and citrus in recent years, but they are not yet mature.
Potassium phosphite mixed with fungicides can also have a synergistic effect. Applying potassium phosphite alone has the same control effect as fungicides. The minimum dose of potassium phosphite plus half a dose of fungicide has the same effect as a full dose of fungicide. Foliar spraying of potassium phosphite is as effective in controlling tuber late blight as direct application of fungicides.
The main mechanism of action of phosphite is as follows:
1. Inhibit the occurrence and development of pathogens by inhibiting Phytophthora spore germination and mycelial growth;
2. Directly attack pathogens and induce crops to produce phytoalexin (PA);
3. Prevent and control plant oomycete diseases by activating the plant’s natural defense response;
4. Induce cells to produce lignin and increase the thickness of cell walls.
It can be seen from the mechanism of action of potassium phosphite that it actually acts as a biostimulant most of the time. It may not directly act on pathogens, but it can stimulate crops to form their own defense system. , equivalent to animal vaccines.
Potassium phosphite has a systemic up-and-down conduction effect and can be transported in both directions in the xylem and phloem of the plant. The absorption rate is faster than that of phosphorus in the phosphate state. It activates crops to produce polyphenols and reactive oxygen molecules, stimulates defense enzyme activity, and targets It has eradication, treatment and preventive effects on infective diseases in crops. Regular use can greatly improve the stress and disease resistance of crops, improve the transformation of long-term pathological conditions of crops, increase the vitality of crops, and has good effects on promoting roots, flowers and fruits. effect.
Development prospects
Phosphite is very effective as a fungicide in inhibiting Oomycete pathogens in different types of plants, including Solanum (potatoes, tomatoes, peppers, eggplants, tobacco, etc.), Brassica and Other leafy vegetables as well as grapes, strawberries, papayas and avocados. Phosphites are not only fungicides, they are also good for plantsIt is a nutrient source and has a good fertilizer effect in increasing the flowering, yield, fruit size and soluble substance content of crops such as strawberries and potatoes. It also has a good effect in reducing the pH value of the solution to suppress weeds.
Whether used as a fungicide or fertilizer, phosphite has been widely used and promoted abroad.
