How to achieve high quality and high yield in lettuce? Improving the cultivation environment is key

Lettuce has two main types: leaf lettuce and stem lettuce, and the market is dominated by the consumption of stem lettuce. Stem lettuce is further divided into spring lettuce, autumn lettuce and overwintering lettuce, and for these lettuces to achieve high yield and high quality, the cultivation environment must be improved in multiple ways.

First, choose a deep-textured soil. It is necessary to choose a loose, fertile sandy loam or clay loam; when nutrients are sufficient, the fleshy underground stem can develop freely and swell and thicken. Lettuce is relatively sensitive to soil acidity and alkalinity (pH value); the most suitable pH for growth is 6.8, and when it is above 7 or below 5, the growth and development of lettuce will be inhibited.

Second, regulate temperature and moisture well. Lettuce can germinate even at lower temperatures, but the optimum germination temperature is 15°C-18°C, and the optimum temperature for growth and development is 15°C-20°C. Before flowering, when the temperature exceeds 28°C, lettuce will quickly bolt, the young fleshy stem will grow excessively, and quality will decline accordingly. However, during the flowering and pod-setting stage, when the temperature is 23°C-30°C, seed maturity is better.

In production, during sowing and seedling raising and field management, the temperature must be adjusted according to the season. For stem lettuce, yield is reflected by the size of the fleshy stem; when the proportion of thick, plump lettuce is high, there is a foundation for high yield and high quality, but robust lettuce must have enough moisture to develop and expand normally. If drought continues, the fleshy stem will contain more crude fiber, the skin will be rough, and the flesh will have a bitter taste. Therefore, in lettuce fields, moist management must be maintained consistently so that the product is tender and delicious with a pure taste.

Third, fertilize scientifically to improve the quality of the tender stem. Stem lettuce is a root and stem vegetable; the appearance of normally growing lettuce should be: leaves thick and flat-spreading, leaves densely arranged, and the growing tip lower than the highest point of the rosette leaves. To promote robust growth of the tender stem, the following points should be grasped in fertilizer application: First, balanced fertilization according to formula; because root vegetables have a relatively large demand for potassium fertilizer, the application ratio of nitrogen, phosphorus and potassium is generally 1:0.5:1.8, and during the fleshy stem swelling stage, the amount of potassium fertilizer should be appropriately increased; Second, during the period when the tender stem enters vigorous growth, prevent "bolting"; if fertility is insufficient and too much water is applied, the tender stem may grow excessively and become slender (waterlogging-induced bolting), while high temperature and drought cause rough stem skin and slender tender stems (drought-induced bolting). For this, during this period, fertilizer and water should be applied heavily, and waterlogging, drought and fertilizer deficiency should be prevented; Third, apply sufficient base fertilizer and topdress in stages. Base fertilizer should be mainly organic fertilizer, combined with high-content inorganic compound fertilizer; apply 3000-4000 kg of decomposed farmyard manure per mu, or 150-200 kg of high-quality commercial organic fertilizer, combined with 40-60 kg of sulfur-based compound fertilizer with relatively high potassium content. In terms of topdressing frequency, autumn lettuce should be topdressed 2-3 times, and overwintering lettuce should be topdressed 3-4 times. In the early growth stage, mainly use dilute clear liquid manure to cultivate strong seedlings; topdressing must not be excessive, to prevent excessive growth; for overwintering lettuce, during the fleshy stem swelling stage, 25-30 kg of urea can be topdressed per mu.

Yu Hongzhang, Xiaogan City Agriculture Bureau, Hubei Province