Application time
When using ethephon to ripen cotton, the application time is very important, generally based on the following 3 points:
a. Most of the cotton bolls that need to be ripened have reached 70%~80% of the boll period (boll age 45 or more). It cannot be too early, otherwise it will affect the quality of cotton.
b. The maximum temperature should be above 20℃ for 3~5 days after spraying. Because ethephon needs a temperature above 20℃ in the cotton body to quickly release ethylene, and considering that it takes several days for ethephon to absorb and play a role, it cannot be too late, otherwise it will affect the ripening effect.
c. It can generally be controlled during the dry frost period (northern cotton area) or 15~20 days after pulling cotton wood (multi-cropped cotton area). Because when the above conditions are met, the ripening effect can be seen 7 days after using ethephon, and the peak of concentrated boll opening appears 10~15 days. The specific application date varies from place to place.
Appropriate dosage
When using ethephon to ripen cotton, the concentration of the liquid is generally 500~800mg/L. At present, the most widely used in my country is ethephon 40%SL, 100~150ml per mu, the amount of water can be adjusted according to the spraying method used, 20~30L of water is used for manual spraying, 15~20L of water is used for motorized spraying, and about 2 times of the original solution is enough for ultra-low spraying.
The dosage can be adjusted according to the following conditions:
a. Consider the use period and the temperature. When the use time is early and the temperature is high in autumn, the concentration can be lower.
b. Consider the crop arrangement. If you want to plant another season after the flowers are harvested, in order to reduce the pulling of stalks and pull the cotton stalks in advance, it is required that 80%~90% of the cotton bolls are opened within 15~20 days, and the concentration can be as high as 2500mg/L.
c. Look at the growth of cotton. If the cotton develops early, the concentration can be lower; if the cotton develops late, the concentration should be higher. For those with good growth and late autumn peach, the middle and lower and middle and upper bolls can be treated in layers and stages, with concentrations of 800~1200mg/L and 1200~1600mg/L respectively.
Spraying technology
After ethephon is sprayed on the cotton plant, it is absorbed and transported in the form of ethephon, and the output from bottom to top is generally low. Therefore, when spraying, the spray head should be sprayed from bottom to top, and the whole plant should be sprayed evenly so that all the bolls can be sprayed. The green bolls after pulling out the cotton wood can also be ripened with ethephon, which can reduce the time of sun-drying and picking, and improve the grade of cotton. Generally, 200~300g of ethephon 40%SL is used for every 100kg of green bolls, and 10L of water is used. After spraying the bolls evenly, they are piled together and covered with plastic film. They begin to crack in 5~7 days and can be fully opened in 10~15 days.