In recent years, China's transgenic insect-resistant cotton has developed rapidly, which has played a key role in restoring and promoting the development of China's high-yield and stable-production cotton planting industry. At present, the planting area of ​​insect-resistant cotton has exceeded half, and it has been found that there are some variations in the reproductive characteristics of insect-resistant cotton, including the characteristics of nutrient absorption and utilization, how to recognize these changes, and then meet their needs in field management. For this purpose, experts are invited to introduce the potassium nutrition characteristics of insect-resistant cotton and the reasonable application of potash fertilizer to all of you for reference only.
The relationship between the source and sink of transgenic cottons is unbalanced, and it is particularly manifested in premature aging. Due to the introduction of insect-resistant genes (Bt), the new insect-resistant genes bring additional physiological consumption to cotton plants, such as the increase of boll weight of plants and leaves Both the source and root volume decreased, and the physiological activity of the root system was weak. Especially in the late period of the boll, the physiological activity of the root of the insect-resistant cotton had been reduced. The root system was the basis for the development of the entire cotton plant. In addition, the root bank decreased while the insect-resistant cotton plant strain The activities of the above-ground organs can be enhanced, such as the high rate of ringing per plant, the early belling, and the high rate of inner bellows and lower bolls. As a result, the insect-resistant cotton is generally easy to exhibit due to the imbalance of the source and bank relationships. The problem of premature aging. In addition, the resistance of carbon-nitrogen metabolism of insect-resistant cotton after bell-mouthing is also disordered, and the roots have strong absorptive capacity at the initial flowering stage and flowering stage, indicating that the nitrogen metabolism is strong, and then, the “root†absorption and assimilation transport function. To reduce, we must also show the phenomenon of premature aging. It can be said that the imbalance of the source-sink relationship is the direct cause of the premature aging of insect-resistant cotton. The premature decline of root function and imbalance of carbon and nitrogen metabolism are the root causes of premature aging of cotton plants.
Insect-resistant cotton is more sensitive to the supply of potash fertilizer. Both agricultural technicians and cotton farmers in the production have found that insect-resistant cotton is more prone to symptoms of potassium deficiency than conventional cotton. Through tests, it is proved that at low potassium levels, insect-resistant cotton (such as new The dry matter weight of cotton 99B) was significantly reduced, and the reduction range was more than 50%-60% lower than that of conventional cotton (such as Zhongmian 36, 35). The main reason for the resistance of insect-resistant cotton to low potassium was root morphology and absorption. Potassium capacity decreased. With the large-scale promotion of transgenic insect-resistant cotton in production, the status of potassium deficiency in cotton fields has become more serious. Moreover, the scientific and technological community initially believes that potassium deficiency may be one of the important causes of premature aging of cotton. Because some fertilization experiments in recent years have shown that sufficient supply of potash can delay the aging of the leaves, some experimental results also prove that sufficient supply of potassium in the key period can extend the development period of bolls by about 25 days, and increase the weight of bolls by 0.2 to 0.5 grams. This shows that the rational application of potash fertilizer can prevent premature aging of cotton.
Potassium fertilizer applied to potassium can alleviate the problem of premature aging of insect-resistant cotton, which is beneficial to improve cotton yield. The chemical control group of Agricultural University further discussed the application of potash fertilizer and the allocation of application amount. The results showed that: Potassium sulphate is better than KCl at the level of 6~8 kg K2O/mu. In order to overcome the problem of premature aging of cotton, potassium fertilization should be divided into base fertilizer and top dressing twice. Moreover, the top dressing should be extended to Potassium is suitable for flowering. The distribution ratio of the two potash fertilizers was “40% basal fertilizer + 60% topdressing (full bloom topdressing)â€. The distribution characteristics of “before light weight and heavy weight†during the application period of potash fertilizer are aimed at delaying the problem of premature aging. In order to fully utilize the physiological functions of potassium nutrition, the synthesis and transportation of photosynthetic products in the later stage of insect-resistant cotton are designed. Its rationality is selected by comparison of a large number of test results. This kind of potassium application technology is different from the previous ones. The proportion of potassium applied to the basal fertilizer on the potassium fertilizer management is obviously reduced. The basal potassium application only accounts for 40%, while the proportion of topdressing potassium application is increased to 60%, and potassium fertilizer will be topdressed. The period was later adjusted to full bloom. If we look back, there are three differences in the distribution of potassium with the previous high-yielding cotton. First, the amount of potassium applied is generally increased; second, the proportion of base potassium is lighter than that of base fertilizer, and the top dressing is heavy; The flowering period, while the management of high-yield cotton in the past emphasized that topdressing should be carried out during the bud period.
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