The cotton boll stage refers to the period from cotton flowering to boll opening, generally from early July to August 30. It lasts for 560 days. During this period, the cotton not only has long branches, leaves, flowers, and bells, but also Due to the influence of internal factors, external factors and other unfavorable factors, it causes the loss of the bolls, so the flowering period is a crucial period for determining cotton production.
According to surveys of the budding, ringing and shedding of 4 varieties of cotton in 4 varieties, under the condition of density of 2500 strains and an average yield of 325.5 kilograms per mu, there are 65.8 single fruit sections (that is, the total number of buds), and 28.8 into bells. The shedding rate was 56.2. Use its buds, bells, and shedding ratios to make graphs.
After the emergence of cotton on June 5, it marked that it was mainly from vegetative growth, and entered the stage of vegetative growth and reproductive growth. The peak period of budding was from June 20 to July 30, and the daily buds were more than 20; In the flowering period of cotton, on the 4th of July, on the 5th of the average, after cotton flowering, it marked that it entered the flowering boll stage, that is to say, it gradually transformed from vegetative growth to reproductive growth, and reached the full flowering stage (ie, the fourth fruiting branch blossomed. ), its vegetative growth (ie, long branches and leaves, long roots) reached the most prosperous period, and then it gradually declined into reproductive growth (ie, flowering, belling, budding). The bolls of cotton rose gradually from flowering to the peak on July 20. Until August 20, 23 bolls per plant accounted for 80% of the total number of bolls. The peak period was July 30. Before and after; Cotton bud bells fall off, generally from the beginning of flowering, no pest damage before flowering, shed little, after flowering, with the increase of the increase in the number of bells, the shedding peak in the peak period after the bell, generally in 7 From January 25 to August 30, the average single plant was shed 24, accounting for 70% of the total number of shedding. The peak was around August 5.
Caused by the fall of the bell, in addition to pest damage, mechanical damage, more than 70% due to malnutrition caused by, and malnutrition, in addition to individual years in individual plots grow too busy, the majority of the nutritional deficiencies. Therefore, re-applying and applying flower and bell fertilizers is an important measure to ensure the nutritional requirements of cotton, promote cotton's many bells, knot large bells, and less fall off.
Scientific fertilization is a high-yielding measure in cotton cultivation and cannot be expected to yield high yields if it is not applied or reduced. The number of flowers and bolls applied depends on the yield, fertility, and seedling conditions. Experiences from all over the country, cotton fields above 300,000 kilograms per mu in northern cotton areas, adequate early fertilization (for example, 20 kg of diammonium in Mushi and 15 kg of potash in the earlier stage), and 10 to 20 kg of urea in Mushi are appropriate. Strong and weak seedlings are applied sparingly, and weaker soil and weak seedlings are used. In the case of insufficient phosphorus and potassium in the early stage, proper application of diammonium and potassium fertilizers, especially in the cotton fields where only 100 kg of compound fertilizer was applied in the early stage, should be supplemented with 7.5 to 10 kg of potassium fertilizer while topdressing urea.
Flower bell fertilizer should be applied early, generally the cotton field is suitable for flower top dressing. This year, the temperature in the north is high and the drought is severe. The flowering period in most cotton fields is earlier than in previous years. Many flowering fields in the cotton field are ahead of schedule and the vegetative growth is lagging behind. It should be combined with drought-resistant watering and early application of flower and bell fertilizer. For strong land, good lyrical condition, and Miao Ziwang, you can apply for 1 to 2 large bells in the lower part, but it should not be later than July 15. For the larger amount of fertilizer applied to cotton fields, it can be divided into two applications. The second topdressing application is generally no later than July 25th. Mu recovery urea 5 ~ 7.5 kg, can prevent premature aging, ensure the need for cover fertilizer.
The method of fertilizing flowers and bells should be adopted in mechanical trenching and deep-seated methods. When fertilizing, do not specifically close to the root and apply it in the midst of big lines. At this time, the cotton root system has developed to the largest extent, and the root hairs are spread throughout the field, and the closer to the cotton plant. The worse the absorption capacity. After urea is applied, watering should not be carried out immediately. Immediately after watering, or in the event of fertilizer, it is likely to cause blue and dryness. Therefore, it is generally recommended to fertilize after or after raining.
Foliar spraying is an auxiliary measure on the basis of applying topdressing fertilizer. In the cotton field where signs of premature decay appear later, 2% urea+potassium dihydrogen phosphate mixture can be sprayed to help increase production. However, you cannot use foliar fertilizer instead of topdressing.
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