Text/Xirui Wang, Yunsong Liu
Boron is one of the 16 essential elements of plants, which is of great significance for the growth and development of plants, flowering and fruiting. With the development of production and scientific research, the understanding of the function of boron is also constantly improving. Production is often due to boron malnutrition, which often produces many problems and deserves in-depth discussion.
<h1 class="pgc-h-arrow-right" data-track="49" > the effect of boron on plants</h1>
In the process of crop growth, boron has a specific physiological function, which can be summarized in the following aspects:
1. Promote pollen formation
Boron promotes pollen formation and pollen tube germination in plants, reduces wheat flowers without fruit, cotton buds without flowers and pollen deformities, etc., to avoid flowers and buds that are easy to fall off, fertilization is not normal, and fruit seeds are not full.
2. Promote cell elongation and tissue differentiation
Boron in plants can promote crop cell elongation and cell division, which is conducive to the growth and elongation of crop roots, avoiding growth point necrosis, leaf deformity, thickening, peel wood embolization, beet heart rot and other phenomena.
3. Promote carbohydrate transport and protein metabolism
Boron promotes the circulation of glucose-1-phosphate and the conversion of sugar. Boron can promote the normal development of vascular bundles in the roots of leguminous crops, so that rhizobia can get an adequate supply of carbohydrates, thereby enhancing the nitrogen fixation capacity of legumes crops and increasing the content of protein.
4. Boron can accelerate enzyme metabolism and lignin formation in plants, and improve the cell wall structure.
Boron can be complexed with phenolic compounds to overcome the inhibition of phenolic compounds on indole acetate oxidase. During lignin formation and xylem duct differentiation, boron controls the activity of hydroxylases and phenolic compound enzymes. Boron is not only tightly bound to the cell wall component, but also necessary for the structural integrity of the cell wall. Together, boron and calcium act as "intercellular cements".
The strengthening of lignin synthesis is conducive to the improvement of crop disease resistance.
5. Increase the amount of nitrogen fixation
Boron in plants can improve the nitrogen fixation capacity of legume vegetable rhizobia and increase the nitrogen fixation of plants.
6. Boron in the plant body can promote early ripening of crops and improve the quality of agricultural products.
Boron can promote the circulation of glucose-1-phosphate and the conversion of sugar, participate in the transportation and metabolism of carbohydrates in crops in plants, increase the composition of crop fruit sugar, improve fruit set rate, and avoid the occurrence of phenomenons affecting fruit dysplasia, deformity, fruit fall and so on. The right amount of boron can increase the starch content of potatoes and the sugar content of sugar beets, increase the amount of fiber in hemp crops, and improve its quality.
7. Boron can enhance crop stress resistance in plants.
A good supply of boron can improve the ability of crops to withstand adversity such as drought, high temperature, cold, humidity, and high winds.
8. Boron has obvious bactericidal effect, and has a good prevention and control effect on scleroclerosis such as rape sclerotia, cotton wilt, verticillium wilt, etc.
These physiological functions of boron have specificity, specificity, especially the role of promoting reproductive growth, which cannot be replaced by any other nutrient.
<h1 class="pgc-h-arrow-right" data-track="138" >2. Boron deficiency symptoms: common and typical symptoms of major crops</h1>
Because insects, viruses, calcium deficiency, and drought can all cause crops to produce symptoms similar to boron deficiency, only tissue analysis can truly determine whether it is a symptom of boron deficiency. However, the symptoms of boron deficiency in some crops are very obvious, mainly in the following 7 aspects:
1. The young leaves are the first to fall ill and gradually become rounder and smaller than normal. However, it is rarely yellowish and generally appears dark green in color.
2, the crop growth point died, the whole crop showed a cluster of forms.
3. The stems and rods of crops become shorter and sometimes twisted.
4. The crop storage tissue becomes thin or necrotic.
5. Openings and cracks appear on the stems and rods of crops, and the fruits are often thrombotic (cracked skin).
6. The fruits of some vegetable species are deformed or show irregular shapes.
7. There are very few root hairs and newly formed roots, and the root system is dysplasia.
8. Partial weakening of boron-deficient plants. The cell division of the stem-forming layer tissue cells is strengthened, and the cells of the forming layer are hyperplasiad (swollen).
Boron affects the synthesis of RNA, especially uracil. Boron-deficient plants have reduced new leaf protein content, which is limited to the cytoplasm, while chloroplast protein content is not affected, so boron deficiency plants are not common.
<h1 class="pgc-h-arrow-right" data-track="139" >3. Symptoms and development of boron deficiency in kiwifruit</h1>
When the kiwi fruit is deficient in boron, it is prominently manifested as: (young tree) skin hole is thick (Xu Xiang, Hua You is obvious). Swelling of the main trunk, poor pollination causes fruit development to be hindered: the fruit is spherical, small (Xu Xiang is obvious); hollow, falling fruit, etc. With the increase of tree age, the cortex cracks, and when it is severe, in the late winter and early spring "frost drought" factor, it will produce serious cracks along some cracks.
<h1 class="pgc-h-arrow-right" data-track="141" > fourth, the reason for boron deficiency</h1>
The main causes of boron deficiency are:
(1) Low soil boron content; (2) high soil pH; (3) low soil organic matter content in sandy soil; (4) Soil soluble boron will be leached out in case of excessive rainfall or irrigation; (5) In drought conditions, the diffusion pathway of boron in soil becomes longer, and the soil solution carrying boron becomes weaker and vulnerable to boron deficiency.
<h1 class="pgc-h-arrow-right" data-track="182" >5</h1>
1. Improve the soil
The application of organic fertilizer in large quantities to improve the soil can improve the symptoms of boron deficiency.
2. Supplement boron fertilizer
One is soil boron fertilizer, and the other is foliar boron fertilizer. In autumn, the base fertilizer was applied in combination, and 10 grams of boron fertilizer was applied to each plant soil. Fertilizer is applied near the capillary roots at the distal end of the root system. The sprinkling method should be used to avoid boron poisoning in the plant and to avoid the loss of boron in the soil.
Foliar spraying of boron fertilizer, starting from the germination stage, combined with spraying, add 0.1% to 0.2% boron fertilizer. Xu Xiang, Huayou and other varieties, when spraying to control pests and diseases during the growth period, must be supplemented with boron fertilizer.
Boron fertilizer and calcium fertilizer (mainly calcium chloride) have the characteristics of mutual promotion and complementarity, and can be used in combination. However, it is necessary to pay attention to the problem of precipitation caused by direct mixing. It can be used alternately, or first add boron fertilizer, then add 0.2% amino acids, stir, and then add calcium chloride to reduce the side effects of direct contact with each other.