Scientific seed retention measures of lettuce

Lettuce, also known as lettuce, Asteraceae lettuce species can form a variety of fleshy tender stems, herbaceous plants in 2012. Alias stem lettuce, lettuce bamboo shoots, green shoots, lettuce. Delivery period: from January to April. It is native to Central or North China. The aboveground stem is edible, the stem skin is white-green, the stem is crisp and tender, the young stem is emerald green, and turns white-green after maturity. Mainly edible fleshy tender stems, which can be eaten raw, salad, fried, dried or pickled, and tender leaves can also be eaten. Stems and leaves contain lettuce and lettuce. It tastes bitter and has analgesic effect. Lettuce has strong adaptability and can be cultivated in spring and autumn or overwintering, mainly in spring and harvested in summer.

Medicinal value of lettuce

1. Dredging and dispelling qi: lettuce tastes fresh and slightly bitter, which can stimulate the secretion of digestive enzymes and increase appetite. Its milky serous fluid can enhance the secretion of gastric juice, digestive gland and bile, thus promoting the function of various digestive organs, especially for patients with decreased digestive function, decreased acidity in digestive tract and constipation.

2. Diuresis and dredging milk: the content of potassium in lettuce is much higher than that of sodium, which is beneficial to the balance of water and electrolyte in the body and promote micturition and milk secretion. It has certain dietotherapy effect on patients with hypertension, edema and heart disease.

3. Strong body, anti-cancer and anti-cancer: lettuce contains a variety of vitamins and minerals, which can regulate the function of the nervous system, and its organic contents are rich in iron elements that can be absorbed by the human body, which is very beneficial to patients with iron deficiency anemia. The hot water extract of lettuce has a high inhibition rate on some cancer cells, so it can be used to prevent and fight cancer.

4. Wide bowel laxation: lettuce contains a lot of plant cellulose, which can promote intestinal wall peristalsis, clear digestive tract, help defecation, and can be used to treat all kinds of constipation.

5. Lettuce has a high content of potassium, which helps to promote urination and reduce the pressure on the atrium, which is very beneficial to patients with hypertension and heart disease. Contains a small amount of iodine, which has a significant impact on people's basic metabolism, mental and physical development and even emotional regulation. Therefore, lettuce has a calming effect, regular consumption helps to relieve tension and help sleep. Different from ordinary vegetables, it is very rich in fluorine, which can participate in the growth of teeth and bones. Can improve digestive system and liver function. Stimulate the secretion of digestive juices, promote appetite, help to resist rheumatic diseases and gout.

Scientific seed retention measures of lettuce

Lettuce is a high temperature sensitive crop, and low temperature is generally not required in vernalization stage. In the stage of development, the requirement of long-day sunshine is not strict, it can blossom not only in spring and summer, but also in autumn, which is more suitable for keeping seeds on its own. So most of the vegetable farmers keep their own seeds. But the seed must be an excellent conventional variety, and attention should be paid to the method of seed retention.

First, the choice of planting land. Farmers often choose excellent individual plants among commercial lettuce, but they should pay attention to the conditions of seed retention. After bolting and flowering, lettuce plants are easy to lodge and reduce yield due to the influence of strong wind and waterlogging, so the seed land should be protected from the wind as far as possible, and the irrigation and drainage conditions are good and not very fertile. Although lettuce is a self-pollinated crop, the outcrossing rate is about 1%. We should pay attention to isolation from other varieties, using both natural distance isolation and time isolation. The natural isolation distance should be 100-300 meters, and the time isolation should stagger flowering period for more than 30 days.

Second, excellent single plant selection. After overwintering, the field selection was carried out when the fleshy lettuce reached the commercial harvest standard. The plants with typical characteristics of this variety, late bolting, close internodes, no lateral branches, few leaves, thick bamboo shoots without cracking and no diseases and insect pests were selected. Unselected plants are harvested and put on the market. The seeds and plants were marked and numbered respectively.

Third, strengthen the field cultivation pipe. The lower leaves and rotten leaves of the selected plants were removed and the soil was cultivated. Open the perimeter ditch and border ditch, and pay attention to often dredge the drainage ditch to prevent blockage and waterlogging in the field. In order to prevent lodging caused by windy and rainy days, it is best to insert brackets. Lettuce is prone to diseases and insect pests such as downy mildew and aphids in the later stage, so it is necessary to do a good job in prevention and control. To control downy mildew, 25% metalaxyl 400,500 times liquid spray can be used to control downy mildew. From the initial stage of the disease, it can be sprayed 2-3 times every 7-10 days; aphids can be controlled with 2500-3000 times solution (also known as imidacloprid, great hero, Kangfuduo, Yichuojing).

Fourth, harvest in time. Around June, when the Corolla turns brown and white hairs appear in the inflorescence, the seeds are basically mature and should be harvested in time, otherwise the white hairs on the seeds are easy to be blown away by the wind, take away the seeds or fall off in case of rain. In view of the great difference in the maturity of different parts of the inflorescence of lettuce, the whole plant should be harvested by stages or most of the inflorescences should be harvested and then dried.