How Do You Make Hydroponic Lettuce?

When it comes to lettuce, no one should be unfamiliar with it, right? Lettuce is a very nutritious green vegetable in today’s life, and in this era of rising prices, it is also more affordable. In order to increase the yield of vegetables, we have implemented soilless lettuce cultivation.

(1) Methods and facilities Soilless cultivation of lettuce is currently more common in developed countries and has advanced technology, high yield and good quality. It is less adopted in China, and there are two general cultivation methods, one is nutrient liquid film technology, and the other is deep liquid technology, mostly with nutrient liquid film technology.

The characteristic of nutrient liquid film cultivation is to make the bare roots of plants grow and develop in the shallow flowing and intermittent flowing nutrient liquid, which can better coordinate the contradiction between water, fertilizer and gas, and supply the nutrients needed by vegetables in each reproductive period in a timely manner. At the same time, save electricity, save liquid, production costs are reduced accordingly. Nutrient liquid film cultivation facilities in the protected area mainly include liquid storage pool, cultivation bed, liquid delivery pipe, water pump, timer, etc.

① Liquid storage tank. According to the cultivated species and cultivated area, set a certain volume of reservoir, generally can be set at a rate of 20-25 cubic meters per mu, mostly with cement pools. The reservoir also prevent leakage, and to cover. Pool set the water level marker, in order to control the nutrient level. The position of the orifice of the return tank should be higher than the nutrient liquid level, using the drop to inject the nutrient liquid, and the splashed water bubbles can add oxygen to the nutrient liquid. The stainless steel spiral pipe is installed in the reservoir for circulating hot and cold water and regulating the temperature of nutrient solution.

②Cultivation bed. Use brick, cement or hard plastic to make cultivation bed, the slope of cultivation bed is lowered by 1 meter for every 80-100 meters (80-100:1). The bed is lined with plastic film to prevent leakage. A thin layer (2-3mm) of nutrient solution is often maintained in the cultivation bed. The cultivation bed is covered with polyvinyl chloride sheets with planting holes. When the seedlings are inserted into the planting holes, the root system hangs or stands upright in the cultivation bed, and a thin layer of nutrient solution at the bottom of the bed keeps flowing slowly, so that the root system growing in the cultivation bed is in darkness and the environment with water, air and nutrients. Since the nutrient solution is a thin layer in the cultivation bed, it is called nutrient film technology.

③Liquid supply system. It consists of inlet pipe, return tank, pump, timer and some fittings. The working time of the pump is controlled by the timer, and the nutrient solution is pumped out from the reservoir at regular intervals, which enters the cultivation bed through the inlet pipe for the crop to absorb and use, and then, flows back to the reservoir through the return tank. Through intermittent liquid supply, the needs of lettuce for oxygen, water and nutrients are met.

Nutrient film technology can also be used for three-dimensional cultivation. According to the specific area and height of the shed, two layers of brackets are welded with angle iron, and cultivation beds etc. can be made of PVC sheets.

(2) Stubble arrangement of loose leaf lettuce and crinkle leaf lettuce has a short growing period and can produce as many as 10 crops in a year. The following arrangement can be applied for reference.

From February to May, 1 crop is sown each month with a nursery period of 25-35 days, planted from late March to early June, harvested 30-40 days after planting, and supplied from early April to early July; from late June to late August, 3 crops are sown with a nursery period of 15-25 days, planted from late July to mid-September, and harvested 25-35 days after planting, and supplied from late August to mid-October; from late September to November, 2 crops are sown with a nursery period of 30 days, and harvested from late September to November. 2 crops, seedling period of 30 days, planting from mid-October to December, harvesting 55-60 days after planting and supplying from mid-December to mid-February of the following year. The growing period of nodular lettuce is longer, and the crop can be reduced appropriately.

(3) Varieties and seedlings

①Variety selection. Soilless lettuce should be used early, heat-resistant, late, adaptable varieties, such as Caesar, Great Lakes 366, crisp, Great Lakes 659, etc., are more desirable varieties of soilless lettuce. ② Preparation before sowing. Lettuce seeds were treated as for other cultivation methods. After that, prepare loose 3 cm thick sponge blocks and cut them into small pieces of 3 cm square, connecting them a little with each other when cutting to facilitate yard leveling. Clean the sponge blocks and place them flat in a watertight seedling tray.

③Sow the seeds. Because lettuce seeds need light when germination, so sowing, the seeds will be treated by hand directly on the surface of the sponge block can be placed on each block of 2-3, and then add enough water to the seedling tray, until the surface of the sponge block soaked prevail.

④Sowing. It is very important to moisturize the seeds after sowing, spray 1-2 times a day with a spray bottle to keep the surface of the seeds moist, cover with shade net and film if necessary, and the seedlings can come out in about 3 days. When the true leaves grow, pour a small amount of nutrient solution on the sponge block, the concentration of which can be 1/3-1/2 of the standard solution concentration, and interplant after the top heart of the true leaves, leaving only 1 plant on each sponge block. The age of seedlings is about 15-30.

(4) Planting management

①Preparation before planting. After the cultivation bed is prepared, install the liquid supply system and carry out the treatment of the facility, inject the prepared nutrient solution into the reservoir before planting, and plant the seedlings in the cultivation holes of PVC plates at a density of 35-50 plants/m2.

②Nutrient solution management. Nutrient solution is recycled. For seedlings planted within one week, the concentration of nutrient solution used can be 1/2 of the standard solution concentration, after one week of planting, the concentration of nutrient solution can be adjusted to 2/3 of the standard solution concentration, and in the late growth period, the standard solution is used. the EC value is controlled at 1.4-1.7mS, pH is controlled at 6.0-6.3, and the nutrient solution is recycled 4-5 times a day.

③Temperature management. Lettuce growth temperature is 15-20 degrees Celsius, suitable for growth in an environment with a large temperature difference between day and night and low night temperature. Daytime temperature control between 18-20 degrees Celsius, the night temperature is maintained at 10-12 degrees Celsius, nutrient solution temperature to 15-18 degrees Celsius is appropriate.

④ Increase the application of carbon dioxide gas fertilizer. Carbon dioxide cylinders or carbon dioxide generators can be used to increase the application of carbon dioxide gas fertilizer to supplement the carbon dioxide in the greenhouse to promote photosynthesis of the plants and improve the yield.

With the improvement of people’s life, the demand is increasing day by day, not only needing annual supply, but also needing products without pollution, and hygiene. Therefore, the above requirements can be achieved by using soilless cultivation. To make the products pollution-free, and high yield, good quality, but also can save water, fertilizer, reduce labor intensity, not subject to soil planting restrictions. Despite the large one-time investment and strict management requirements, it is an inevitable development trend. Therefore, soilless cultivation has become the object of research by experts, and this technology can be vigorously promoted.

Post time: Aug-29-2022