Causes and prevention methods of bolting of lettuce with small leaves and few stem details

Lettuce has been cultivated year-round in many places. However, in the cultivation, it is easy to appear the early bolting phenomenon of lettuce with few leaves, sparse stem details and club-shaped lettuce, which affects the yield and reduces the quality. The causes and control measures of early bolting of lettuce are introduced as follows:

Lettuce bolting

(1) improper selection of varieties. Countermeasures: for example, lettuce planted in spring, summer and autumn should be grown in high temperature and long sunshine, so middle and late maturing varieties with high temperature tolerance and low sensitivity to long sunshine should be selected. Early-maturing varieties, if planted late in early spring, are easy to bolt because of high temperature and long sunshine in the later stage.

(2) the sowing date is not suitable. Countermeasures: to cultivate lettuce, suitable sowing time should be made. generally, spring lettuce should be sowed in early October, protected field around late January of the following year, summer lettuce sowing in early April, autumn lettuce sowing in early August, winter lettuce sowing in late August.

(3) poor management at seedling stage. Specific measures: seedling bed bottom fertilizer is mainly organic fertilizer, can be combined with appropriate amount of compound fertilizer; appropriate amount of sparse sowing, and time seedling, control watering, bed soil is dry and wet, shading seedling should gradually cover and early cover the mulch after the whole seedling, after 3 leaves, no longer shade; summer and autumn lettuce seedling stage, can be sprayed twice 500 mg / kg solution, can effectively prevent apprentice growth.

(4) planting is not in time. Measures: the appropriate age seedlings with 5 leaves and 6 leaves should be planted in time, the seedling age of autumn sowing and spring harvest was about 40 days, the seedling age of spring sowing and summer harvest or summer sowing and autumn harvest was about 25 days, and the seedling age of autumn sowing and winter harvest was 30-35 days.

(5) the cultivation is too dense. Measures: under normal circumstances, spring harvest lettuce can be appropriately close planted with 8000 plants per mu; summer harvest lettuce should be sparsely planted and 5000 plants per mu should be planted due to high temperature and long-day sunshine; autumn harvest lettuce can be planted with 7000 plants per mu with good merchandise and high yield.

(6) less ploughing and loosening soil. Measures: after planting slow seedlings, it is necessary to plough in time, hoe deeply and thoroughly, so as to facilitate squatting seedlings, promote root development, and increase the number of rosette leaves and the growth of tender stems.

(7) the amount of water is not suitable. Measures: watering lettuce should be appropriate, not only to prevent "waterlogging", but also to prevent "drought". Before rosette leaf formation and plant ridge sealing, watering should be properly controlled to make the border surface dry and wet; after ridge closure, the water supply should be increased to keep the border surface moist and make the tender stem grow and expand rapidly.

(8) insufficient fertility or partial application of nitrogen fertilizer. Measures: base fertilizer should be fully applied, 4000 kg of rotten manure and 25 kg of compound fertilizer should be applied per mu, and organic fertilizer should be combined with compound fertilizer. In addition, we should also apply slow seedling fertilizer, cluster plant fertilizer, shoot fertilizer, ammonium sulfate or urea 15 kg per mu or 1000 kg of dilute dung water for the first two times.

(9) the climatic conditions are not suitable. Measures: in addition to strengthening the management of fertilizer and water in the high temperature season, Daizhuangsu should be sprayed regularly. Spraying Daizhuangsu can delay the bolting of lettuce, promote the growth of leaves, increase the nutritional area of lettuce and thicken the tender stem. Spraying usually begins at the rosette stage, once every 7 days and 10 days, for a total of 2 times and 3 times, with a concentration of 350 mg / kg.

(10) the harvest is not timely. Measures: if the harvest is delayed, pinching and removing buds can effectively control the high bolting of lettuce, that is, in the "flat mouth" period, remove the top growing point or buds of lettuce in time on a sunny day. The untopped lettuce can inhibit the top growth, increase the reflux of nutrients in the stem, prevent the hollow of the tender stem, promote the hypertrophy of the bamboo shoot, harvest 5 / 7 days late and increase the yield by 10% / 20%.