Diagnosis and Fertilization Technology for Cotton Boron Deficiency
2024-06-05 07:05:31
In 2006, cotton showed a serious and extensive range of symptoms of boron deficiency, both in the southern cotton region and in the northern cotton region. Trace elements such as zinc, boron, copper, manganese, molybdenum, and iron have attracted attention as essential elements of plant nutrition, beginning in the 20-30s of the last century. Worldwide, in the 1960s and 1970s, trace element fertilizers began to be widely used in production, which is an emerging field, which is developing rapidly and the use area is expanding.
In the 1940s, China began to study the effects of trace elements on plant growth and development. In the 1950s, soil microelement content and its morphology were studied. In the 1960s, the application of micro-fertilizer in production was studied. It was found that molybdenum application of molybdenum, fertilization of rape and cotton, and zinc application in rice and corn increased significantly, which greatly promoted the research and application of micro-fertilizer.
First, boron is an essential element of plants: boron and mannitol, mannan and other cell wall components form a complex, involved in cell elongation, nucleic acid metabolism, etc., so boron belongs to plant energy storage and structural integrity of micronutrients. Boron has an effect on the reproductive process of plants. The content of boron in the organs of plants is the highest. When boron is absent, the anthers and filaments shrink, the tapetum tissue is destroyed, and the pollen is poorly developed. Boron has the function of inhibiting the formation of toxic phenolic compounds. Therefore, when boron is deficient, the phenolic compound content in the plant is too high, the buds and top buds are necrotic, the apical dominance is lost, and the branches are many.
Second, the content of available boron in China's soil: Since the 1970s, the investigation of soil trace elements has been carried out in China. The results show that the area of ​​boron deficiency in soil is more than 40%. The content of boron in the soil varies greatly and has a band-like distribution, which is closely related to factors such as soil parent material and soil type. Generally speaking, the arid areas in the western inland are rich in boron, and the wet areas in the east are low in boron. The boron-deficient areas mainly include southern red soil areas, which are distributed in Guangdong, Fujian, southwestern Jiangxi and western Zhejiang. The water-soluble potassium is less than 0.25 mg/kg (0.25 ppm). The boron-deficient soil in the north is mainly the soil developed by the alluvial deposits of the loess and the Yellow River, mainly distributed in the Loess Plateau and the North China Plain. Hebei Province is also one of the key provinces with boron deficiency. Zheng Wenzhao reported in 1982 that the average available boron content in Henan Province was 0.25 mg/kg. There are also areas with small areas of boron deficiency in northeastern Hubei and western Anhui. Xie Zhenyi reported in 1986 that the soil available boron content in the low hilly areas of northeastern Hubei was 0.26 mg/kg, with a range of 0.13-0.65 mg/kg.
3. Symptoms of boron deficiency in cotton: When the cotton is deficient in boron, the leaves are curled and shrunk, the top growth is blocked, the side branches are more, and the buds are clustered. The development of buds, flowers and bells is abnormal. The cotton buds are deformed, and the vascular bundles of stems and petioles are damaged. The green belt will cause buds instead of flowers, flowers and bells.
1. Seedling stage: cotyledons become smaller, petiole is longer, leaves are thicker, color becomes darker, brittle and easy to fold, wilting and drooping is "a" shape (normal "Y" on the leaves); Stagnant, axillary buds sprout, forming a long, small leaf deformity seedlings. The cotton plant with short onset is short-branched and compact.
2. Bud stage: when the boron is deficient, the petiole is longer, the young bud is yellow, and the temporal lobe is open. It is intuitively like to be wormed, and it is easy to fall off. The middle and lower buds are few or even buds, and the upper buds grow with the buds. Also fell off one after another. Boron deficiency in cotton is susceptible to verticillium wilt.
3, flowering and bolling period: less flowering, small flower shape, weak growth, the petals can not be fully unfolded, the corolla is covered by the leaves, the pollen grains are poorly viable, easy to abort, the pollen is small and long after pollination, the tip is sharp and curved, the bell The base is dark brown, cracking is poor at maturity, and the vomiting is not smooth.
4. Belt identification: When the boron-deficient cotton plant is in the present 5--8 true leaves, there will be more dark green belts on the petiole, the tissue of the ring zone will be swollen, and the feeling of unevenness will be felt when the hand is touched. The petiole of the diseased plant showed obvious browning in the internal tissues of the annulus. The darker the color of the annulus, the denser the distribution, the more obvious the swelling and the more serious the boron deficiency. According to the survey, the boron-bearing cotton field in the Yellow River Basin has a petiole rim rate of 3%.
4. Effectiveness of boron application in cotton fields: The effectiveness of boron application in cotton fields is closely related to the effective boron (water soluble boron) content in soil. According to 306 field trials conducted by Huazhong Agricultural University in the main cotton-producing areas, the application of boron fertilizer was poor when the soil available boron was higher than 0.8 mg/kg. Similar results were obtained in Sichuan Province through 113 field trials.
5. Soil conditions affecting boron availability
1. Soil pH (pH): The effective boron increases with the increase of PH between pH 4.7 and 6.7, but the effective boron decreases with the increase of PH between pH 7.1 and 8.1.
2, soil organic matter: In a nutshell, soil organic matter increased, the soil effective boron increased accordingly; the topsoil is rich in organic matter, and the effective boron content is also high. Because organic matter has an adsorption effect on boron, when the organic matter is increased to a certain amount, it will cause a decrease in effective boron.
3. The relationship between boron and water: precipitation and evaporation cause soil water movement, which also affects the growth and decline of soil boron. Analysis of the difference in available boron content in different precipitation areas indicates that the soil available boron content is also lower in areas with more precipitation, and the effective boron content is higher in areas with less precipitation. However, the effective boron in the soil enters the plant body by mass flow. Therefore, when the soil is dry, the amount of boron absorbed by the crop roots is reduced, which is easy to cause boron deficiency.
Sixth, boron application technology: comprehensive results of cotton boron fertilizer test, boron-deficient soil (effective soil boron less than 0.5 mg / kg) and potential boron-deficient soil (effective soil boron less than 0.8 mg / kg), cotton application of boron fertilizer Both can obtain better yield increase effects.
1. Base fertilizer: Before the cotton is planted, it can be combined with the land preparation. The borax is about 0.5 kg, which can be mixed with nitrogen, phosphorus, potassium and other fertilizers. It can also be applied after mixing the dry soil.
2. Fertilizer: When the cotton is planted, the boron fertilizer strip is applied to the seeding ditch, and about 0.5 kg of borax is used for the mu, and the soil is mixed well with the fine dry soil. Pay special attention to avoid contact between boron fertilizer and seeds, and do not use boron fertilizer for seed dressing.
3, foliar spray: the advantage of spraying one is that boron is not easy to transfer from the old tissue to the new tissue in the plant body, the boron can meet the needs of the new tissue in time, and the second is to save labor with the medicine and fertilizer. When the boron is severely deficient, it can be sprayed once every 10 days from the beginning of the bud, and sprayed 4-6 times in total, which can receive better yield increase effect. When the boron is slightly deficient, it can be sprayed once in the cotton bud stage, the initial flowering stage, and the flowering and bolling stage. Spraying the concentration with 0.2% borax solution is better. The amount of liquid spray: 30-40 kg per mu in the bud period, 40-50 kg per mu in the initial flowering period, and about 60 kg per mu in the flowering and ringing period.
(Liu Chuntai, chief agronomist of China Agricultural Science and Technology Association)
In the 1940s, China began to study the effects of trace elements on plant growth and development. In the 1950s, soil microelement content and its morphology were studied. In the 1960s, the application of micro-fertilizer in production was studied. It was found that molybdenum application of molybdenum, fertilization of rape and cotton, and zinc application in rice and corn increased significantly, which greatly promoted the research and application of micro-fertilizer.
First, boron is an essential element of plants: boron and mannitol, mannan and other cell wall components form a complex, involved in cell elongation, nucleic acid metabolism, etc., so boron belongs to plant energy storage and structural integrity of micronutrients. Boron has an effect on the reproductive process of plants. The content of boron in the organs of plants is the highest. When boron is absent, the anthers and filaments shrink, the tapetum tissue is destroyed, and the pollen is poorly developed. Boron has the function of inhibiting the formation of toxic phenolic compounds. Therefore, when boron is deficient, the phenolic compound content in the plant is too high, the buds and top buds are necrotic, the apical dominance is lost, and the branches are many.
Second, the content of available boron in China's soil: Since the 1970s, the investigation of soil trace elements has been carried out in China. The results show that the area of ​​boron deficiency in soil is more than 40%. The content of boron in the soil varies greatly and has a band-like distribution, which is closely related to factors such as soil parent material and soil type. Generally speaking, the arid areas in the western inland are rich in boron, and the wet areas in the east are low in boron. The boron-deficient areas mainly include southern red soil areas, which are distributed in Guangdong, Fujian, southwestern Jiangxi and western Zhejiang. The water-soluble potassium is less than 0.25 mg/kg (0.25 ppm). The boron-deficient soil in the north is mainly the soil developed by the alluvial deposits of the loess and the Yellow River, mainly distributed in the Loess Plateau and the North China Plain. Hebei Province is also one of the key provinces with boron deficiency. Zheng Wenzhao reported in 1982 that the average available boron content in Henan Province was 0.25 mg/kg. There are also areas with small areas of boron deficiency in northeastern Hubei and western Anhui. Xie Zhenyi reported in 1986 that the soil available boron content in the low hilly areas of northeastern Hubei was 0.26 mg/kg, with a range of 0.13-0.65 mg/kg.
3. Symptoms of boron deficiency in cotton: When the cotton is deficient in boron, the leaves are curled and shrunk, the top growth is blocked, the side branches are more, and the buds are clustered. The development of buds, flowers and bells is abnormal. The cotton buds are deformed, and the vascular bundles of stems and petioles are damaged. The green belt will cause buds instead of flowers, flowers and bells.
1. Seedling stage: cotyledons become smaller, petiole is longer, leaves are thicker, color becomes darker, brittle and easy to fold, wilting and drooping is "a" shape (normal "Y" on the leaves); Stagnant, axillary buds sprout, forming a long, small leaf deformity seedlings. The cotton plant with short onset is short-branched and compact.
2. Bud stage: when the boron is deficient, the petiole is longer, the young bud is yellow, and the temporal lobe is open. It is intuitively like to be wormed, and it is easy to fall off. The middle and lower buds are few or even buds, and the upper buds grow with the buds. Also fell off one after another. Boron deficiency in cotton is susceptible to verticillium wilt.
3, flowering and bolling period: less flowering, small flower shape, weak growth, the petals can not be fully unfolded, the corolla is covered by the leaves, the pollen grains are poorly viable, easy to abort, the pollen is small and long after pollination, the tip is sharp and curved, the bell The base is dark brown, cracking is poor at maturity, and the vomiting is not smooth.
4. Belt identification: When the boron-deficient cotton plant is in the present 5--8 true leaves, there will be more dark green belts on the petiole, the tissue of the ring zone will be swollen, and the feeling of unevenness will be felt when the hand is touched. The petiole of the diseased plant showed obvious browning in the internal tissues of the annulus. The darker the color of the annulus, the denser the distribution, the more obvious the swelling and the more serious the boron deficiency. According to the survey, the boron-bearing cotton field in the Yellow River Basin has a petiole rim rate of 3%.
4. Effectiveness of boron application in cotton fields: The effectiveness of boron application in cotton fields is closely related to the effective boron (water soluble boron) content in soil. According to 306 field trials conducted by Huazhong Agricultural University in the main cotton-producing areas, the application of boron fertilizer was poor when the soil available boron was higher than 0.8 mg/kg. Similar results were obtained in Sichuan Province through 113 field trials.
5. Soil conditions affecting boron availability
1. Soil pH (pH): The effective boron increases with the increase of PH between pH 4.7 and 6.7, but the effective boron decreases with the increase of PH between pH 7.1 and 8.1.
2, soil organic matter: In a nutshell, soil organic matter increased, the soil effective boron increased accordingly; the topsoil is rich in organic matter, and the effective boron content is also high. Because organic matter has an adsorption effect on boron, when the organic matter is increased to a certain amount, it will cause a decrease in effective boron.
3. The relationship between boron and water: precipitation and evaporation cause soil water movement, which also affects the growth and decline of soil boron. Analysis of the difference in available boron content in different precipitation areas indicates that the soil available boron content is also lower in areas with more precipitation, and the effective boron content is higher in areas with less precipitation. However, the effective boron in the soil enters the plant body by mass flow. Therefore, when the soil is dry, the amount of boron absorbed by the crop roots is reduced, which is easy to cause boron deficiency.
Sixth, boron application technology: comprehensive results of cotton boron fertilizer test, boron-deficient soil (effective soil boron less than 0.5 mg / kg) and potential boron-deficient soil (effective soil boron less than 0.8 mg / kg), cotton application of boron fertilizer Both can obtain better yield increase effects.
1. Base fertilizer: Before the cotton is planted, it can be combined with the land preparation. The borax is about 0.5 kg, which can be mixed with nitrogen, phosphorus, potassium and other fertilizers. It can also be applied after mixing the dry soil.
2. Fertilizer: When the cotton is planted, the boron fertilizer strip is applied to the seeding ditch, and about 0.5 kg of borax is used for the mu, and the soil is mixed well with the fine dry soil. Pay special attention to avoid contact between boron fertilizer and seeds, and do not use boron fertilizer for seed dressing.
3, foliar spray: the advantage of spraying one is that boron is not easy to transfer from the old tissue to the new tissue in the plant body, the boron can meet the needs of the new tissue in time, and the second is to save labor with the medicine and fertilizer. When the boron is severely deficient, it can be sprayed once every 10 days from the beginning of the bud, and sprayed 4-6 times in total, which can receive better yield increase effect. When the boron is slightly deficient, it can be sprayed once in the cotton bud stage, the initial flowering stage, and the flowering and bolling stage. Spraying the concentration with 0.2% borax solution is better. The amount of liquid spray: 30-40 kg per mu in the bud period, 40-50 kg per mu in the initial flowering period, and about 60 kg per mu in the flowering and ringing period.
(Liu Chuntai, chief agronomist of China Agricultural Science and Technology Association)
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