When is the latest time to plant cotton?
Cotton is the seed fiber of plants in the Gossypium genus of the Malvaceae family. Its place of origin is the subtropics, and it was first introduced to China for cultivation at the end of the 19th century. It has since been widely cultivated in all cotton-producing regions across the country, and has replaced tree cotton and Asiatic cotton. At present, the countries with the highest cotton production in the world are China, the United States, India, Brazil, Mexico and other places. Now let us take a look together at when the cotton planting time is!
Cotton planting time
Due to differences in weather and climate among various regions, the cotton planting time also differs. Generally speaking, the cotton planting time is around April each year. In fact, starting in the third month of spring, farmers begin to buy cotton seeds to plant cotton. However, because cotton is not planted directly in the ground like beans, at this time they are cultivating cotton seedlings, so the true cotton planting time should be late March to early April.
Cotton planting conditions
1. Light: Cotton is a light-loving crop and is suitable for growing under relatively sufficient light conditions. Both the light compensation point and the light saturation point are high. According to measurements, the light compensation point of a single cotton leaf is 750-1000 lux, and the light saturation point is 70,000-80,000 lux. Under normal circumstances, the suitable range of light intensity for cotton leaves is 8000-70000 lux, and within this range the photosynthetic intensity increases as light intensity increases.
2. Water: Cotton growth requires absorbing water from the soil, and the physiological water requirements differ at each growth stage. From sowing to emergence, the water content of the 0-20 cm soil layer should preferably be 70-80% of field capacity; at the seedling stage, the water content of the 0-40 cm soil layer should preferably be 60-70% of field capacity; at the early bud stage, the water content of the 0-60 cm soil layer should preferably be 65-75% of field capacity; after the full bud stage, the water content of the 0-80 cm soil layer should preferably be 70-80% of field capacity and must not be lower than 60-65%; at the boll-opening stage, the relative water content of the soil should preferably remain at 55-70%. According to relevant research, during the entire growth period of a cotton field, about 2/3 of the water is consumed by transpiration, and 1/3 is consumed by soil evaporation.
3. Soil: Cotton growth and development require water and nutrients, which are mainly obtained from the soil through the root system. The required temperature and air are partly taken from the soil, and at the same time the mechanical support of the soil is needed for growth. The quality of the physical, chemical and biological properties of cotton field soil largely restricts the yield and quality of cotton. Soil moisture, nutrients, temperature, air, saline-alkali content, texture and so on all have a great influence on cotton growth.
Cotton seedling-raising techniques
1. Plastic-film frame seedling raising: Most ecological cotton regions across the country use the plastic-film frame seedling raising method. It mainly involves sowing and covering with soil, then placing arches and covering with film, sealing the surroundings tightly, and ventilating to lower the temperature after full emergence.
2. Nutrient block seedling raising: Nutrient block seedling raising is also called square seedling raising or block seedling raising. Different places have different names because of the different measures adopted. For example, using river mud, pond mud and the like as bed soil for square seedling raising is called river mud square seedling raising.
3. Flat plastic-film mulching seedling raising: Flat plastic-film mulching seedling raising saves labor and cost, simplifies management procedures, and has simple operating techniques that are easy for people to master. The film is laid directly on the seedbed, and when the cotton sprouts push through the soil, the film is broken to release the seedlings. The thickness of the plastic film used is only 18% of the thickness of commonly used agricultural film. In areas with much rainy weather during the seedling stage, disease-infected seedlings and dead seedlings are relatively serious when this method is used for seedling raising, so the seedling raising period should be appropriately delayed in production, and it can be applied in cotton fields transplanted from late crops.
4. Double-film seedling raising: Double-film seedling raising is a seedling raising method in which, after sowing and covering with soil, a layer of plastic film is first laid flat and then an arched shed is added. It solves the problem of stiff seedlings and diseased seedlings easily caused by rainy and low-temperature weather after sowing in early spring. The cotton seedlings raised are of good quality and the bud stage occurs earlier.
5. Ventilated mesh film seedling raising: Ventilated mesh film seedling raising is to cut conventional plastic film along the center line, sew a 10-15 cm wide nylon window screen in the middle, and cover it on the frame. Temperature and humidity are naturally regulated through the open part of the ventilated mesh, with no need to uncover it by day and cover it at night.