Boron is one of the micronutrients that must be grounded by crops. Dicotyledonous plants generally have higher boron content than monocotyledonous plants. According to the analysis, monocotyledons contain 2 - 11 mg / kg of boron, and dicots contain 8 - 95 mg / kg of boron. Dicotyledonous plants have the highest boron content in leguminous and cruciferous crops. The boron content of different organs of crops is also different. The boron content in wheat leaves is higher, 4-9 times higher than that of stems. The boron content in ears is between stems and leaves, and the boron content in grains is lower. Crops contain a certain amount of boron, and sometimes can still exhibit symptoms of boron deficiency, mainly because of the poor ability of boron to reuse and redistribute in crops.
Boron is not a component of crops. No organic compounds of boron are found in crops, but it has an important effect on certain physiological processes of crops. Boron promotes the functioning of carbohydrates.
Plants have a suitable amount of boron, which can improve the supply of organic matter in various organs of crops, normal crop growth, increase seed setting rate and fruit set rate (fruit tree). Boron has a special effect on the insemination process. The distribution of boron in the flower is based on the content of stigma and ovary. Most of them can stimulate the germination of pollen and the elongation of pollen tubes, and the insemination can be carried out smoothly.
When the crop is deficient in boron, the anthers and filaments shrink, and pollen cannot form. Therefore, the outstanding performance of boron-deficient crops is “flowers and not realâ€. Boron regulates the formation and operation of organic acids in the body. When the crop is deficient in boron, the organic acid accumulates in the root, and the cell differentiation and elongation of the apical meristem are inhibited, and the cork is formed, causing root necrosis.
Crops sensitive to boron fertilizers are leguminous and cruciferous crops (such as rapeseed), which may be related to the high boron content in their bodies. In addition, there are fruit trees such as beets, hemp, and fruit. Wheat, corn, rice and other food crops are not as sensitive to boron as the above crops, but boron is still effective in boron deficiency.
(I) The status of boron in the soil Boron is widely found in nature. Animals, plant residues, rainfall, minerals, etc. are all sources of boron in the soil, the most important of which is minerals.
Therefore, the content of boron in the soil is related to the parent material. The soil developed by the deep rock is rich in boron in the igneous rock. The soil in the arid area is more than the soil in the wet area, and the coastal area is more than the inland area. There are also some differences in boron content in different soil types in the same area. The sand with a texture of sand has a lower boron content. In addition, the effective boron content in the soil is also affected by soil pH, farming system, cultivation management, climate and ecological conditions.
According to the utilization of boron in soil by crops, the form of boron in soil can be divided into three types: water-soluble boron, acid-soluble boron and total boron. The effective boron that can be utilized by crops is mainly water-soluble boron and acid-soluble boron.
All boron is mainly boron present in tourmaline, which is not easily dissolved and cannot be used by crops. It is the main body of effective boron, accounting for about 6% of total boron content. The acid-soluble boron includes a borate having a high solubility in an acid solution and some borate having a low solubility, and although it is low in content, it can also be utilized for crop roots.
The effectiveness of boron is affected by various factors, and a certain dynamic balance is maintained in nature. The insoluble boron-containing mineral gradually releases boron, and the delayed boron supply is an effective boron storage.
The factors that cause the reduction of effective boron in the soil are:
1. pH The availability of boron in the soil varies with the acid-base reaction of the soil. Boron is most effective at pH 5-7, and the effectiveness is gradually reduced at pH 5 or below.
2, drought and drought enhanced the fixation of boron, drought accompanied by high temperature, boron formed insoluble compounds, and the effective boron decreased. However, in the rainy season and flooding, the water-soluble boron is also washed to reduce the soil available boron content.
(2) Commonly used boron fertilizer varieties and application methods
1, boron fertilizer varieties
Commonly used boron fertilizer varieties and properties
2. Application method Boron fertilizer can be used as base fertilizer, top dressing, seed fertilizer and foliar fertilizer. Boron mud contains a certain amount of boron, which is used as base fertilizer, and the cost is low, which is suitable. 225 kg per hectare can be mixed with calcium. Fruit trees such as citrus are 1.5 to 2 kg per plant, and are applied in combination with calcium or organic fertilizer.
The base fertilizer must be applied evenly to avoid excessive concentration of boron in local areas, which may cause crop poisoning. When borax is used as the base fertilizer, it is higher per hectare and contains a large amount of sodium ions, which must be taken care of.
Borax and boric acid are easily soluble in water, and it is better as a seed fertilizer and top dressing. Borax soaking, the general application concentration is 0.02% - 0.05%, first dissolve the fertilizer in warm water of 40 °C, completely dissolve, add enough water, pour the seeds into the solution, soak for 4-6 hours, remove and dry Dry, you can sow.
Page spraying: Generally, a concentration of 0.1% - 0.2% borax or boric acid solution is applied. Rape can be sprayed with 1500 grams of borax and 750 kilograms of water per hectare of seedlings 2 to 3 days before transplanting, which can increase the survival rate. Seedling, moss and flowering can be sprayed with 0.1% - 0.2% borax solution.
Depending on the size of the seedlings, 750 to 1500 kg of borax solution per hectare. According to the boron deficiency and other conditions of rapeseed, choose 2-3 times of spraying time and the corresponding concentration and amount of fertilizer. Guocun sprayed better during the flowering and young fruit periods. It can also be sprayed with Bordeaux mixture and 0.5% urea. Cotton should be sprayed at the beginning of the bud period, sprayed once every half month, and even sprayed 2-3 times.
Boron directly affects the development of crop reproductive organs and should be applied early. Because boron has poor ability to run in plants, it should be sprayed several times, usually 2 to 3 times.
(III) Fertilizer effect of boron fertilizer At present, China's boron fertilizer is mainly used in rapeseed and cotton, and food crops, fruit trees, etc. are also applied. It is generally considered that the soil water-soluble boron < 0.5 mg / kg is boron deficiency.
The Institute of Oil Research of the Chinese Academy of Agricultural Sciences has conducted five-year tests in Jichun, Jianli and other places in Hubei Province. The application of borax per hectare is 3.75-15 kg, and the yield of rapeseed is increased by 225-375 kg, increasing the yield by 15%-25%. According to the Xiaogan test point, the fat content of sprayed fermented rapeseed increased from 13.73% (control) to 41.94%.
In the 16 spray tests of Tianmen County, Hubei Province, the average hectare of lint-producing lint was 1341 kg, and the equivalent amount of fresh water was 1149 kg per hectare. The yield of lint cotton was 192 kg per 666.7 m2, which increased the yield by 16.7%. The main reason is that the spraying of boron reduces the bud ringing, increases the number of peaches, and increases the weight of the bell and the clothing.
In the northeastern region, when the soil is effective boron < 0.2 mg / kg, the wheat is inaccurate, with 450 g of boric acid per hectare, and the number of infertile grains per ear is reduced from 9.6 to 0.8.
Spraying boron on fruit trees such as citrus and apple can increase the fruit setting rate. The Jinxian County of Liaoning used 0.3% borax solution to spray apples, and the fruit setting rate increased by 23.2% to 24.9%.
The critical value of boron deficiency in soil is very close to the value of boron poisoning. It must be noted that boron fertilizer should not be excessive.
This article URL: The effect of boron fertilizer on crops How to use boron fertilizer correctly after crop boron deficiency [Figure]
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