The diagnosis and prevention of boron deficiency in crops
2020-07-04 15:13:15
(I) Symptoms Symptoms of boron deficiency occur in the growth and development of shoots, young leaves, tuberous roots, or fruits. The symptoms vary from crop to crop.
(1) The growth point of the tip and the growth of the heart are obstructed, whitening or browning and necrosis, stimulating the growth of lateral buds (partial lateral buds also necrotic) and clustered or clustered.
(2) The leaves are deformed and become thicker and more fragile or wrinkled and curled. Some crops have symptoms of yellowing between veins.
(3) Thickening of petiole or stem becomes thick, cracked, corked, or immersed in water.
(4) Corky or black hearts in roots or tubers.
(5) Boron deficiency inhibits pollen, nectar formation, and development of pollen tubes and affects pollination, resulting in severe flowering or fruit drop.
(6) The fruit is deformed, develops slowly, the skin or pulp is partially immersed, the skin is thickened, the rate of juice is low, and the seed is not well developed.
For example, the lack of boron in wheat has no obvious symptoms in the early stage, because of stamen development after heading, the anther is empty, pollen abortion can not complete the normal pollination, and the lack of boron in the upper leaves of the corn has irregular chlorotic spots or Stripe, ear malformation, uneven ranks, sparsely grained, often brownish brown pods at the base of grains; soybeans lacking in boron seedlings, budding, withered to death, axillary buds malformed, rough old leaves thickened; peanuts lack of boron fruit Atrophy of the needle, a few of the fruits of the soil are mostly pods; sunflower lack of boron top buds, axillary buds germinate, leaf shrinkage, main vein biased to one side, disk shape is small, loses the ability to turn with the sun, empty shells, pods More; potato growth point and branch tip death, short internodes, lateral buds clustered, rough old leaves thickened, curled edge, small tuber, deformed, brown or brown material appear inside; yellow leaves of citrus boron, tip, There are yellow leaves, "blight disease", thicker veins, epidermis burst, serious fruit drop, uneven surface of the fruit, thick skin, fruit is hard and juicy, small and hard, said "stone disease"; Apple's lack of boron shoot tip Shrinking, even withered, a large number of weak lateral branches occur, similar to "lobular disease", young fruit surface watery brown spots, necrosis, dry shrinkage hardening, depression, cracking, known as fruit disease; boron deficiency in vegetable crops, according to the main symptoms Classification: First, the growing point atrophy and death, leaf shrinkage, distortion deformity. More common in spinach, practical sugar beet, cabbage and other cabbage. The second is that the stems and leaves and petioles are cracked, short and hard and brittle. Such as celery's crack stem disease, the old leaf petioles appear a lot of cracks; tomato petiole and leaf veins are hardened and become brittle. The third is root tissue fleshy roots internal tissue necrosis brown, corked, such as radish and other brown heart disease, also known as brown heart rot. The fourth is peel, fruit flesh necrosis of wood, such as cucumber fruit corky cracking, tomato skin cracking.
(b) Prone environmental conditions
(1) For riverbeds, gravels, sandy soils, or red soils in areas with abundant rainfall, the boron content in the soil is extremely low due to long-term leaching and the crops are easily boron.
(2) In calcareous soils with high pH, ​​boron is easily fixed and its effectiveness is low, causing boron deficiency in crops.
(3) When the drought occurs, the movement of boron in the soil and the absorption of crops are both hindered and boron deficiency is more likely to occur.
(4) Partial application of nitrogen fertilizer increased boron deficiency.
(5) Plant sensitive crops. Dicotyledonous plants are more sensitive than monocotyledonous plants. Boron deficiency in fruit and vegetable crops is generally more common in larger crops. Field crops include rape, beet, sunflower, sesame, and cotton; citrus, apples, grapes, cabbage, cabbage, and celery in fruit and vegetable crops are sensitive to boron. Gramineous crops are generally insensitive to boron except for wheat and corn.
(c) Diagnosis
1. Diagnostic form As mentioned above, boron deficiency symptoms are diverse, complex, and focus should be paid attention;
(1) Variations in the apical tissue, such as atrophy of the terminal apical malformation, death, and abnormal sprouting of axillary buds.
(2) Leaf (including petiole) changes in morphological texture, such as thicker leaves, thickened petiole, hardened, brittle, cracked, etc.
(3) Changes in robust organs, such as abnormal abscission of buds, poor development of pollen, and false results.
2. Plant analysis and diagnosis
Leaf total boron can well reflect the plant's nutritional status. Generally, when the mature leaves of the crop contain boron 200, it is deficient in boron, normal from 50 to 200 hours, sugar beets and soybeans>100 and 50 respectively are boron deficient.
3. Soil diagnosis
Generally, the amount of hot water-soluble boron 0.5 mg/kg is an indicator, the appropriate amount is 0.5~1.0 mg/kg, the abundance or excess is >1.0 mg/kg, and the critical value of different crops: cotton is seriously deficient in boron.
(1) Because of soil cultivation, use resistant varieties. There is a great difference in boron tolerance between different crop varieties. In the areas where boron deficiency is common, few or no sensitive crops are selected, or resistant varieties are used to reduce losses.
(2) Apply boron fertilizer to soil. Boron is used as boron fertilizer, boric acid, boron sludge, etc., but commonly used borax. The general amount of field crops is 7.5~15 kg/ha, the amount of boron is large such as sugar beet 22.5~30 kg/ha, mud or water is applied, spray 0.1%~0.2% borax liquid, dosage is 750~1500 per hectare Grams; fruit trees are applied as trees, 50 to 100 grams per tree. Since the general crop contains a narrow range of boron, the appropriate amount is close to the excess limit, and it is easily overdose, so the amount should be strictly controlled; in fact, the borax is dissolved slowly, and it should be dissolved first with hot and cold water, then the amount of water should be applied.
(3) During the dry season, pay attention to irrigation.
(4) Soils with high pH use physiological acidic fertilizers such as ammonium sulfate to reduce the pH of the root ring and increase the effectiveness of boron.
(1) The growth point of the tip and the growth of the heart are obstructed, whitening or browning and necrosis, stimulating the growth of lateral buds (partial lateral buds also necrotic) and clustered or clustered.
(2) The leaves are deformed and become thicker and more fragile or wrinkled and curled. Some crops have symptoms of yellowing between veins.
(3) Thickening of petiole or stem becomes thick, cracked, corked, or immersed in water.
(4) Corky or black hearts in roots or tubers.
(5) Boron deficiency inhibits pollen, nectar formation, and development of pollen tubes and affects pollination, resulting in severe flowering or fruit drop.
(6) The fruit is deformed, develops slowly, the skin or pulp is partially immersed, the skin is thickened, the rate of juice is low, and the seed is not well developed.
For example, the lack of boron in wheat has no obvious symptoms in the early stage, because of stamen development after heading, the anther is empty, pollen abortion can not complete the normal pollination, and the lack of boron in the upper leaves of the corn has irregular chlorotic spots or Stripe, ear malformation, uneven ranks, sparsely grained, often brownish brown pods at the base of grains; soybeans lacking in boron seedlings, budding, withered to death, axillary buds malformed, rough old leaves thickened; peanuts lack of boron fruit Atrophy of the needle, a few of the fruits of the soil are mostly pods; sunflower lack of boron top buds, axillary buds germinate, leaf shrinkage, main vein biased to one side, disk shape is small, loses the ability to turn with the sun, empty shells, pods More; potato growth point and branch tip death, short internodes, lateral buds clustered, rough old leaves thickened, curled edge, small tuber, deformed, brown or brown material appear inside; yellow leaves of citrus boron, tip, There are yellow leaves, "blight disease", thicker veins, epidermis burst, serious fruit drop, uneven surface of the fruit, thick skin, fruit is hard and juicy, small and hard, said "stone disease"; Apple's lack of boron shoot tip Shrinking, even withered, a large number of weak lateral branches occur, similar to "lobular disease", young fruit surface watery brown spots, necrosis, dry shrinkage hardening, depression, cracking, known as fruit disease; boron deficiency in vegetable crops, according to the main symptoms Classification: First, the growing point atrophy and death, leaf shrinkage, distortion deformity. More common in spinach, practical sugar beet, cabbage and other cabbage. The second is that the stems and leaves and petioles are cracked, short and hard and brittle. Such as celery's crack stem disease, the old leaf petioles appear a lot of cracks; tomato petiole and leaf veins are hardened and become brittle. The third is root tissue fleshy roots internal tissue necrosis brown, corked, such as radish and other brown heart disease, also known as brown heart rot. The fourth is peel, fruit flesh necrosis of wood, such as cucumber fruit corky cracking, tomato skin cracking.
(b) Prone environmental conditions
(1) For riverbeds, gravels, sandy soils, or red soils in areas with abundant rainfall, the boron content in the soil is extremely low due to long-term leaching and the crops are easily boron.
(2) In calcareous soils with high pH, ​​boron is easily fixed and its effectiveness is low, causing boron deficiency in crops.
(3) When the drought occurs, the movement of boron in the soil and the absorption of crops are both hindered and boron deficiency is more likely to occur.
(4) Partial application of nitrogen fertilizer increased boron deficiency.
(5) Plant sensitive crops. Dicotyledonous plants are more sensitive than monocotyledonous plants. Boron deficiency in fruit and vegetable crops is generally more common in larger crops. Field crops include rape, beet, sunflower, sesame, and cotton; citrus, apples, grapes, cabbage, cabbage, and celery in fruit and vegetable crops are sensitive to boron. Gramineous crops are generally insensitive to boron except for wheat and corn.
(c) Diagnosis
1. Diagnostic form As mentioned above, boron deficiency symptoms are diverse, complex, and focus should be paid attention;
(1) Variations in the apical tissue, such as atrophy of the terminal apical malformation, death, and abnormal sprouting of axillary buds.
(2) Leaf (including petiole) changes in morphological texture, such as thicker leaves, thickened petiole, hardened, brittle, cracked, etc.
(3) Changes in robust organs, such as abnormal abscission of buds, poor development of pollen, and false results.
2. Plant analysis and diagnosis
Leaf total boron can well reflect the plant's nutritional status. Generally, when the mature leaves of the crop contain boron 200, it is deficient in boron, normal from 50 to 200 hours, sugar beets and soybeans>100 and 50 respectively are boron deficient.
3. Soil diagnosis
Generally, the amount of hot water-soluble boron 0.5 mg/kg is an indicator, the appropriate amount is 0.5~1.0 mg/kg, the abundance or excess is >1.0 mg/kg, and the critical value of different crops: cotton is seriously deficient in boron.
(1) Because of soil cultivation, use resistant varieties. There is a great difference in boron tolerance between different crop varieties. In the areas where boron deficiency is common, few or no sensitive crops are selected, or resistant varieties are used to reduce losses.
(2) Apply boron fertilizer to soil. Boron is used as boron fertilizer, boric acid, boron sludge, etc., but commonly used borax. The general amount of field crops is 7.5~15 kg/ha, the amount of boron is large such as sugar beet 22.5~30 kg/ha, mud or water is applied, spray 0.1%~0.2% borax liquid, dosage is 750~1500 per hectare Grams; fruit trees are applied as trees, 50 to 100 grams per tree. Since the general crop contains a narrow range of boron, the appropriate amount is close to the excess limit, and it is easily overdose, so the amount should be strictly controlled; in fact, the borax is dissolved slowly, and it should be dissolved first with hot and cold water, then the amount of water should be applied.
(3) During the dry season, pay attention to irrigation.
(4) Soils with high pH use physiological acidic fertilizers such as ammonium sulfate to reduce the pH of the root ring and increase the effectiveness of boron.
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