Planting techniques of lettuce

Lettuce is a 1-2-year-old crop of Compositae lettuce, with shallow and dense roots, mostly distributed in the soil layer of 20cm to 30cm. Lettuce likes cold climate, short-day sunshine and low temperature are beneficial to the growth and development of lettuce, while long sunshine and high temperature are easy to bolt and blossom. The tissue of lettuce is crisp and tender, and the water content is high, which requires a uniform and sufficient water supply in the whole growing period.

Planting season

Lettuce has a wide adaptability, according to the market demand, the selection of different varieties can be arranged to sow, annual balanced production and supply. Tonghai (main season) is mainly sown in autumn and winter and harvested in winter and spring. The main varieties are Yurang No. 1, No. 5, Round Leaf No. 1, four Seasons Round Leaf Hybrid and so on. In summer, it is mainly composed of big flowers and leaves and bamboo leaves.

Soil preparation and fertilization

It is appropriate to select the soil with loose soil, good drainage, rich organic matter and strong water and fertility conservation, deep ploughing and drying, applying 2-3 tons of mature farm manure per mu, fine soil preparation after 7 days, soil moisture with 1.8-1.9 meters, flat soil moisture in the main season and high soil moisture in the off-season.

Sowing seeds

When the seedling field is ready, the seeds are sown directly on the seedling field. After watering, the seedling land is irrigated with 4.5% Pepsi EC 3000 times and 5% Kung Fu EC 3000 times to prevent underground pests. 15-20 square meters of seedling land is needed for planting in the field per mu. Generally, the seed amount per mu is 25,30g, covered with a sunshade net, and then compacted.

Generally transplant according to the row spacing of 32 × 35 cm, planting 4800-5200 plants per mu, and eliminate the seedlings whose stems have been enlarged when transplanting to avoid early bolting.

Field management

Watering in time after transplanting, watering ammonium hydrogen with water and adding 10 kg calcium per mu after transplanting survived. In the future, water and fertilizer control, strengthen mid-tillage, rosette stage to leaf ridge watering and topdressing, urea 10kg / mu, potassium sulfate 5kg / mu, dry and wet later. When the stem began to enlarge, the third topdressing was applied with 50 kg of ternary compound fertilizer, 10 kg of potassium sulfate and 15 kg of urea per mu.

Pest control

1. Disease

① downy mildew: lettuce is particularly serious with downy mildew, which is easy to occur at high temperature and humidity. Metalaxyl manganese zinc and disinfectant alum are used 20 days after planting. At the initial stage of the disease, 687.5 grams / liter silver farinol suspension 1000m 1500 times solution, 66.8% mildew doke wettable powder 1000m 1500 times solution, 77.2% downy mildew water agent 1000ml 1700 times solution can be used to control downy mildew.

② leaf spot, brown spot: 75% chlorothalonil (daconine) wettable powder 1500ml 2000 times solution; 10% Shigao (difenoconazole) water dispersible granule 3000ml 3500 times.

③ Sclerotinia sclerotiorum disease: in recent years, the damage of Sclerotinia sclerotiorum is also quite serious, and it is a disease of low temperature and high humidity. When the temperature is about 5: 15 ℃ and the relative humidity is more than 85%, it is beneficial to the occurrence and invasion of bacteria. In addition, viral diseases can be prevented and treated with poison elimination, Haopu and so on.

2. Insect pests

① aphids: 50% imidacloprid EC 3500 Mel 4000 times.

② leaf miner: the adults can be treated with 1.8% avermectin EC 4000 Mel 5000 times, and the larvae can be controlled with 75% Qianke (cystomide) wettable powder 4500Mel 5000 times.

Harvest

When the tip of the main stem and the tip of the highest leaf of lettuce can be harvested at ordinary times, the tender stem is long, the texture is crisp and tender, the quality is good, and the old leaves can be removed.