Matters needing attention in advance of cotton sowing date

Is it possible to advance the sowing date of cotton? According to the practice of cotton sowing for many years, the lesson in this aspect is very profound. Indeed, using plastic film mulching to raise seedlings in a nutrition bowl, cotton seedlings can also be cultivated by sowing seeds in mid-late March and early April, and a large-scale demonstration has been made in production, but the result is that it is very difficult to manage and it is difficult to ensure that the whole seedling is strong. First, the cold wave is frequent in the first and middle of April, the temperature varies greatly, the north wind patronizes many times, and it is difficult to uncover the film of the seedling bed; second, in case of continuous overcast and rainy weather, the cotton seedlings on the seedling bed are difficult to ventilate and easily form line seedlings, which leads to cotton seedling lodging; third, low temperature and overcast rain is also easy to cause diseases such as blight, anthrax and sudden collapse, resulting in the death of seedlings in the seedling bed. Fourth, sowing early to prolong the age of cotton seedlings, forcing cotton seedlings to be transplanted to the field prematurely, early-planted cotton seedlings encounter a cold wave, often due to lack of seedlings and broken ridges due to dead seedlings, generally 10% / 20% and 30% / 50%, respectively. In recent years, many new varieties have been introduced in cotton production, especially hybrid insect-resistant cotton, which is more expensive. If the lack of seedling area is too large, it will not only cause economic losses, but also make it difficult for cotton to achieve one sowing, one transplant and one whole seedling, the planned cotton field area will often fail, and it will be even more difficult to ensure high yield and bumper harvest by planting good cotton seeds.

In the face of the emergence of warm winter climate, what kind of choice should be made in the sowing date of fine cotton seeds? According to many years' experience, in order to avoid or reduce the loss of fine cotton seeds, the following links should be emphasized in the technology of seedling raising and transplanting in nutrition bowl.

Understanding the temperature requirements of cotton seedling emergence according to the study, the lowest limit temperature of cotton seed germination is 10.5 ℃, the temperature of emergence is more than 12 ℃, and the active accumulated temperature of sowing and emergence is 80 ℃ ~ 100 ℃.

Understanding the local climate law take the middle reaches of the Yangtze River as an example, the average temperature is more than 9 ℃ in late March, 13 ℃ in early April and 16 ℃ in mid-April. Therefore, trial sowing can be conducted in the first ten days of April, and sowing in the middle can be concentrated in time and labor. Sowing in this period is more reliable.

Generally speaking, it is safe to transplant strong seedlings from late April to early May, or it is safer for cotton seedlings to have 3 true leaves, because at this time the young stems begin to Lignification and the stress resistance is enhanced. From the inherent experience, it is called "time to unequal seedling, seedling to unequal time".