With the expansion of hybrid rapeseed planting area, the symptoms of soil boron deficiency in the growth stages of rapeseed are more and more obvious, and the area of ​​occurrence is expanding. Atrophy due to boron deficiency has risen to become a major physiological disease in rapeseed production.
1 Types of atrophy and false symptoms caused by boron deficiency The rapeseed atrophy is occurring in all stages of rapeseed, but the symptoms are different, and can be divided into four types.
1.1 Atrophy at seedling stage (year-old dead seedling) In the rapeseed seedling stage, the new leaves grow slowly, the leaves begin to darken green, the leaves become smaller and become brittle, the leaves end rewind, and the edges of the leaves turn purple. The tissue turns yellow and gradually develops to form purple-blue spots. The roots are few, thin and short, and the root neck is swollen purple. Finally, the whole plant withers and dies, resulting in the shortage of rapeseed.
1.2 Before the atrophy, the growth was normal, and the symptoms began to appear at the beginning of the year. At the early stage, the leaves shrunk, the color became dark green or purple, the sputum was slow or even stagnant, and the internodes were short and thick. The final plant height was only 1/ of the normal strain. 3 or so; the root neck is swollen, the roots are short and thin, the inflorescences can not be extended, the flower buds are clustered together, a few can be flowering, but can not form pods and wither, the serious whole plant shrinks and dies.
1.3 The flowering period shrinks until the flowering, the appearance growth is basically normal, but after entering the flowering stage, the stolons are stagnant, the branches are short, fine and many, the inflorescences are not fully elongated, the flower buds are dense, most of them can be flowered, and a few pods can be formed. However, when the young fruit stage falls off, it is rarely able to be firm, and the flower buds and inflorescence segments are withered at the end, and many small branches are extracted from the base to form secondary flowering.
1.4 Flowers are not planted The plants do not shrink, the color of stems and leaves is basically normal, and the inflorescence segments are elongated and soft, which is different from normal plants. It can bloom normally, and the condition of insemination is basically not strong or partially firm, but the solid pods are short, the angle of birth is small and the radish is horny, some pods are purple-gray, the shape of the seeds is irregular, and the size is different. . The late end of the inflorescence is not thankful for the flower, and there is a phenomenon of "returning flowers".
2 Analysis of the causes of boron deficiency 2.1 Soil boron deficiency, nitrogen and boron ratio imbalance The effective boron content in the soil is lower than the critical value of 0.5mg/kg. One of the soil samples contains boron or because of the high available nitrogen content, the proportion of nitrogen and boron is out of balance, and the symptoms of boron deficiency are prominent.
2.2 Variety of Variety According to the survey, the cabbage-type and mustard-type local varieties have mild incidence, and the conventional Brassica napus takes place seriously, and the hybrid rapeseed is the most serious. The varieties with long growth period are heavy, and the growth period is short. Hybrid rapeseed is particularly sensitive to boron fertilizer.
2.3 Large-scale continuous cropping The field of planting rapeseed for 1 to 2 years is light, and the disease is severe for more than 3 years. Because of the long period of continuous cropping, a large amount of boron in the soil is consumed, and it is not replenished, resulting in serious soil boron deficiency or imbalance of nitrogen and boron. At the same time, the rapeseed that is continuously used as a field is weak, susceptible to disease, and its ability to absorb nutrients is also reduced.
2.4 Reduction of organic fertilizer application The field of organic fertilizer is light, and the application of organic fertilizer is less or no weight is applied to the field.
3 Prevention and control strategy To prevent and control rapeseed deficiency, it is necessary to adopt comprehensive prevention measures based on supplementation of boron fertilizer.
3.1 Implement rotation for rotation Use rapeseed-rice-wheat or rapeseed-rice-axain or rapeseed-kenaf-wheat to prevent continuous cropping for more than 3 years.
3.2 Expand the area of ​​deep ploughing, increase the application of organic fertilizer to expand the area of ​​machine cultivating, and change the shallow ploughing to deep ploughing to increase the depth of ploughing. Increase the amount of organic fertilizer input, and increase the application of soil and fertilizer by 3000-4000kg per mu.
3.3 Application of Boron Fertilizer According to the effective boron content of soil and the occurrence of boron deficiency, the cultivated land can be divided into severe boron deficiency zone (0.25mg/kg or less), boron deficiency zone (0.25~0.41mg/kg) and mild boron deficiency zone. (0.41 ~ 0.5mg / kg), the implementation of the application of boron, according to local conditions, and carefully do the bottom and follow-up. In the severely boron-deficient area, the application of boron fertilizer is 1~1.5kg per mu, the boron deficiency area is 0.75~1kg per mu, and the mild boron deficiency area is 0.5~0.75kg per mu. It can also be combined with NPK as base fertilizer. Use, the effect is better.
Top dressing is mainly used for foliar application. Spraying twice in the seedling stage and the flood season, the spraying concentration is 0.1%-0.2%, that is, using 50-100kg of boron fertilizer and 50kg of water, spraying the leaves evenly, or spraying with potassium dihydrogen phosphate or urea.
1 Types of atrophy and false symptoms caused by boron deficiency The rapeseed atrophy is occurring in all stages of rapeseed, but the symptoms are different, and can be divided into four types.
1.1 Atrophy at seedling stage (year-old dead seedling) In the rapeseed seedling stage, the new leaves grow slowly, the leaves begin to darken green, the leaves become smaller and become brittle, the leaves end rewind, and the edges of the leaves turn purple. The tissue turns yellow and gradually develops to form purple-blue spots. The roots are few, thin and short, and the root neck is swollen purple. Finally, the whole plant withers and dies, resulting in the shortage of rapeseed.
1.2 Before the atrophy, the growth was normal, and the symptoms began to appear at the beginning of the year. At the early stage, the leaves shrunk, the color became dark green or purple, the sputum was slow or even stagnant, and the internodes were short and thick. The final plant height was only 1/ of the normal strain. 3 or so; the root neck is swollen, the roots are short and thin, the inflorescences can not be extended, the flower buds are clustered together, a few can be flowering, but can not form pods and wither, the serious whole plant shrinks and dies.
1.3 The flowering period shrinks until the flowering, the appearance growth is basically normal, but after entering the flowering stage, the stolons are stagnant, the branches are short, fine and many, the inflorescences are not fully elongated, the flower buds are dense, most of them can be flowered, and a few pods can be formed. However, when the young fruit stage falls off, it is rarely able to be firm, and the flower buds and inflorescence segments are withered at the end, and many small branches are extracted from the base to form secondary flowering.
1.4 Flowers are not planted The plants do not shrink, the color of stems and leaves is basically normal, and the inflorescence segments are elongated and soft, which is different from normal plants. It can bloom normally, and the condition of insemination is basically not strong or partially firm, but the solid pods are short, the angle of birth is small and the radish is horny, some pods are purple-gray, the shape of the seeds is irregular, and the size is different. . The late end of the inflorescence is not thankful for the flower, and there is a phenomenon of "returning flowers".
2 Analysis of the causes of boron deficiency 2.1 Soil boron deficiency, nitrogen and boron ratio imbalance The effective boron content in the soil is lower than the critical value of 0.5mg/kg. One of the soil samples contains boron or because of the high available nitrogen content, the proportion of nitrogen and boron is out of balance, and the symptoms of boron deficiency are prominent.
2.2 Variety of Variety According to the survey, the cabbage-type and mustard-type local varieties have mild incidence, and the conventional Brassica napus takes place seriously, and the hybrid rapeseed is the most serious. The varieties with long growth period are heavy, and the growth period is short. Hybrid rapeseed is particularly sensitive to boron fertilizer.
2.3 Large-scale continuous cropping The field of planting rapeseed for 1 to 2 years is light, and the disease is severe for more than 3 years. Because of the long period of continuous cropping, a large amount of boron in the soil is consumed, and it is not replenished, resulting in serious soil boron deficiency or imbalance of nitrogen and boron. At the same time, the rapeseed that is continuously used as a field is weak, susceptible to disease, and its ability to absorb nutrients is also reduced.
2.4 Reduction of organic fertilizer application The field of organic fertilizer is light, and the application of organic fertilizer is less or no weight is applied to the field.
3 Prevention and control strategy To prevent and control rapeseed deficiency, it is necessary to adopt comprehensive prevention measures based on supplementation of boron fertilizer.
3.1 Implement rotation for rotation Use rapeseed-rice-wheat or rapeseed-rice-axain or rapeseed-kenaf-wheat to prevent continuous cropping for more than 3 years.
3.2 Expand the area of ​​deep ploughing, increase the application of organic fertilizer to expand the area of ​​machine cultivating, and change the shallow ploughing to deep ploughing to increase the depth of ploughing. Increase the amount of organic fertilizer input, and increase the application of soil and fertilizer by 3000-4000kg per mu.
3.3 Application of Boron Fertilizer According to the effective boron content of soil and the occurrence of boron deficiency, the cultivated land can be divided into severe boron deficiency zone (0.25mg/kg or less), boron deficiency zone (0.25~0.41mg/kg) and mild boron deficiency zone. (0.41 ~ 0.5mg / kg), the implementation of the application of boron, according to local conditions, and carefully do the bottom and follow-up. In the severely boron-deficient area, the application of boron fertilizer is 1~1.5kg per mu, the boron deficiency area is 0.75~1kg per mu, and the mild boron deficiency area is 0.5~0.75kg per mu. It can also be combined with NPK as base fertilizer. Use, the effect is better.
Top dressing is mainly used for foliar application. Spraying twice in the seedling stage and the flood season, the spraying concentration is 0.1%-0.2%, that is, using 50-100kg of boron fertilizer and 50kg of water, spraying the leaves evenly, or spraying with potassium dihydrogen phosphate or urea.
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