NFT Cultivation Technology of Lettuce

NFT cultivation of lettuce requires that it be carried out under protected facilities and erected using pipelines. During the implementation of factory-based pipeline laying, horizontal pilings must be carried out at both ends and the middle of the pipeline, so that the heights are aligned so that people can stand. The operation is appropriate, and the pile frame is required to be level and neat. The pipes should not be too long, otherwise the end vegetables will grow poorly and unevenly due to uneven nutrient solution circulation and supply. Generally, each planting pipe should be 7.5 m long, and the longest should not exceed 15 m. Choose the pipe material It should also be a tap water pipe made of non-toxic materials, otherwise it will affect the quality of vegetables due to chemical pollution residues

It is better to lay the piping system with a landslide with a slightly higher water inlet end and a lower drain end. Generally, a slope of 8/1 000 is more appropriate. The pipes shall be laid out neatly and uniformly, with uniform row spacing, which is conducive to the management of production operations and the cultivation of holes The hole is punched at a distance of 20 cm, and an electric punch with a diameter of 5 cm can be selected for efficient production. When arranging and laying the pipes, they should be neat to facilitate the ventilation of the vegetables, and the level of the liquid inlet pipe is slightly higher, which is more conducive to the return circulation of the nutrient solution. The size of the nutrient solution pool is based on the cultivation area. Generally, the amount of circulating nutrient solution should not exceed 50% of the total amount, and the power of the water pump is used to make the nutrients circulate.

Make a 50×50×50 filter pond on the nutrient solution return pipe to filter the substrate and roots and other impurities during cultivation. And install ultraviolet rays or ozone generators and other sterilization devices on the return pipe to effectively kill harmful bacteria in the nutrient solution

Soilless seedlings of lettuce

50-hole plugs are used for plug seedlings, which are just the same size as the cultivation holes, which is convenient for transplanting. Reusable plug trays should be disinfected and cleaned first to prevent pathogenic bacteria from being carried. The substrate is a composite substrate with a mixture of grass charcoal: vermiculite: perlite 1:1:1 and add 1 kg of calcium carbonate (limestone), 0.145 kg of calcium nitrate, 0.145 kg of potassium sulfate, and 1.5 kg of superphosphate per cubic meter. After stirring, it will be used as seedlings. The matrix, the matrix should be fully moistened before filling, generally 60% is appropriate, hold the matrix with your hand, there is no water squeezed out, loose your hand will form a clump, but lightly touch, the matrix will disperse

Transplanting lettuce

Transplanting time is very important. Too small root system does not form a complete root lump. The matrix is easily washed away by the nutrient solution when transplanted into the tube, and the whole plant is washed into the tube. If the seedling period is too long, it may cause too long stems, tall seedlings, etc. , Affect the late growth. Lettuce seedlings are usually grown for 10 to 15 days. When the seedlings have 4 to 6 true leaves, select lettuce seedlings that are strong, grow vigorously, and the root system tightly entangles the substrate to form a complete root tuft, free of diseases and insect pests for transplanting.

When transplanting, lightly press the bottom of the plug tray with your hand to separate the plug from the substrate. The substrate filled with roots is taken out directly, and the whole root system is stuffed into the cultivation hole, and the control system is turned on to allow the nutrient solution to circulate. . 3.2 Nutrient solution configuration and management The nutrient solution configuration is the core of NFT cultivation technology. The nutrient solution formula and control directly affect the growth, yield and quality of crops. The nutrient solution can use the Japanese garden test formula calcium nitrate 945 mg/L, magnesium sulfate 493 mg/L, ammonium dihydrogen phosphate 153 mg/L, potassium nitrate 809 mg/L, and trace elements iron 40 mg/L and manganese sulfate 2.13 mg/L, boric acid 2.86 mg/L, copper sulfate 0.08 mg/L, zinc sulfate 0.23 mg/L, ammonium molybdate 0.02 mg/L, or South China agricultural large leafy vegetable formula, and a nutrient solution formula modified according to local water quality.

The water used in the nutrient solution should be clean and pollution-free. The pH should be adjusted to around 6.5, and then the nutrient solution raw materials should be added for configuration. When the nutrient solution is prepared, the calcium source, phosphorus source and trace elements should be dissolved separately to prevent precipitation . Lettuce has different nutrient solution concentrations in different periods, about 10 days after planting, EC: 1.0~1.5, 10~20 days after transplanting, EC: 1.5~2.0, 20 days until harvest, EC: 2.0~2.5, pH value is controlled at 5.5~ 6.5. Check the concentration and pH of the nutrient solution every day. If the concentration of the nutrient solution is too low, add mother liquor. As the growth water of lettuce evaporates, the nutrient solution becomes less, and tap water is automatically added. The general principle of nutrient solution control: the smaller the seedling, the smaller the concentration of the nutrient solution, the larger the lettuce, the greater the concentration, the lower the temperature, the higher the concentration of the nutrient solution, and the higher the temperature, the concentration of the nutrient solution should be as low as possible; the concentration of the nutrient solution should be adjusted sooner or later. Make the concentration of the nutrient solution relatively high at night and relatively low during the day