First, the cause of lettuce twitching. 1. Improper selection of varieties. There are many varieties of lettuce, their adaptability and their sensitivity to sunlight and temperature are also different. Generally, early-maturing varieties are more resistant to low temperature than medium- and late-maturing varieties and have lower temperature resistance, which means they are more sensitive to high temperatures and long days. Therefore, suitable varieties should be selected according to the cultivation season and cornices. For lettuces harvested in spring or summer, they should use medium- and late-maturing varieties that are resistant to high temperatures and are unresponsive to long-day sunlight because they grow under conditions of high temperatures and long days. If you use early-maturing varieties it is easy to get high convulsions. 2. Poor cultivation and management. Overcultivation is too dense and the density of colonization is too large; too much rainfall, excessive soil moisture; insufficient fertility or partial application of nitrogen fertilizer, it is easy to cause plants to grow high and grow long.
Second, preventive measures. 1. According to the local natural ecological conditions to select the appropriate species, the appropriate sowing date, seedling and transplanting planting period. 2. Rational water and fertilizer management in the field, especially the regular spraying of chlormeine is an effective measure for control of early bolting of lettuce cultivation in high temperature season. The spraying of chlormequat is generally started at the beginning of the rosette period, once for 7-10 days, for 2-3 times in succession, and the application concentration is 350 mg/L. 3. Harvest in time. The harvest of lettuce is suitable for the period when the heart leaves and the outer leaves are “flatâ€, and if they are not harvested in time, the tender stems will quickly lick high twitches. If you delay the harvest, you can pick up the growth point or bud at the top of the lettuce during the “flat mouth†period. After the top of the plant can inhibit the growth of the top, increase the return of nutrients stems, prevent hollow stems, promote stems hypertrophy, generally postponed 5 - 7 days harvest.