Biological characteristics of lettuce and efficient planting methods
Lettuce can also be called leaf lettuce, goose, etc. It has not been popular in China for a long time, but in recent years, the area of ​​lettuce has expanded, and it is popular on the table of the people and the menu of the restaurant owner. Today, I am going to talk to you about the growth characteristics of lettuce and the key points of cultivation techniques.
1 Characteristic characteristics
Lettuce, shallow roots. The roots are developed, the main root group is distributed in the soil layer under the surface of 20cm; the lettuce is light and yin; the lettuce is cold and cold, avoiding high temperature and drought, frost resistance and freezing.
2 Types and varieties
Among the cultivars, they can be divided into two types: one is a ball-shaped lettuce, and the outer leaves are bright. The other type is a loose-leaf type, the leaf clusters are semi-erect, and the inner leaves are not covered. Some are also enclosed in oval loose leaf balls, which are more heat resistant. The main cultivated in China is wrinkled leaves and knotted lettuce.
3 Cultivation techniques
3.1 Select land, land preparation, and base fertilizer
3.1.1 Land selection
Lettuce is generally grown on high-quality, fertile land. It is advisable to use root vegetables, beans, vegetable fields, etc. in the front.
3.1.2 Combining soil preparation with base fertilizer
Generally, the chicken manure or sheep manure is 2,000-3,000 kg per 667 m, and then deep-turned and flattened to make a width of 1.50 m in the north-south direction.
3.2 variety selection
According to the local climatic conditions, cultivation season, cultivation methods and market demand, select suitable varieties, such as Olympia, Caesar, Queen, Emperor and other varieties. Among them, Caesar and Queen are more resistant to high temperature, early maturity, disease resistance and high yield, suitable for spring, summer and autumn cultivation. Olympia has strong cold resistance and high yield, suitable for winter and early spring production. The emperor has good cold resistance and strong heat resistance and is suitable for cultivation in any season.
3.3 sowing seedlings
3.3.1 Seasonal selection
According to the temperature requirements of the lettuce growth period, the northeast and northwestern alpine regions are mostly spring sowing summer harvest, the North China region and the Yangtze River valley can be cultivated in spring and autumn, and the south China region can be planted from September to February of the next year, from November to April. reward. In hot summer areas, it is necessary to pay attention to the measures of cooling when planting in autumn, and pay attention to the problem of early convulsions. Since 1990, with the development of cultivation facilities, the use of conservation facilities to cultivate lettuce has basically been phased sowing and annual production supply.
3.3.2 Soaking seeds and germination, cultivating strong seedlings
Lettuce seeds are small, and good conditions are required for germination and emergence, and planting methods for seedling transplanting are often used. When the average temperature in the past is higher than 10 °C, it can be raised in the open field; when it is below 10 °C, appropriate protective measures are needed.
3.3.3 Seedbed preparation
In summer, nursery should adopt measures such as shading, cooling, and rain prevention. The seedbed soil should be finely crushed and leveled. Apply 10 kg of decomposed farmyard manure and 0.1 kg of phosphate fertilizer per square meter. Spread well, plow the tillage, level the surface, and spread a thin layer of fine soil on the surface. For each hectare, use 30% of the pre-emergence herbicide to apply 1.5 L of collateral oil, and spray it evenly on the kneading surface 1 d before sowing. Pour the bottom water before sowing. After the underwater seepage, sprinkle a thin layer of fine soil on the surface of the clam and immediately seed. 25g seeds can be planted in 667 square meters of field.
3.3.4 Seed treatment
The minimum temperature for seed germination is 4 °C, and the germination temperature is 15-25 °C. When the temperature is above 25 °C, the germination rate is significantly decreased. In order to promote germination, germination should be carried out. The method is as follows: firstly soak with well water for about 6h, wash and take it with wet gauze, pay attention to ventilation, hang on the water surface of the well to germination or wet the seed in a petri dish lined with filter paper, place it in 4 Treat the refrigerator in the refrigerator room of ~6~C for 24 hours, then place the seeds in a cool place to keep warm and germination. When 80% of the seeds are white, they can be sown. In order to soak evenly, the treated seeds are mixed with a small amount of fine tidal soil, mixed, and evenly spread, covered with soil 0.5cm, covered with film after winter sowing, to warm and moisturize, cover the sunshade net or straw after sowing in summer, Moisturize, cool down, and promote seedlings.
3.3.5 Seedling management
The suitable temperature for seedling growth is 12-20 °C, and the suitable temperature during the daytime is 17-25 °C. If the leaf ball grows poorly above 25 °C or the temperature inside the ball is too high, the heart leaf will rot and the temperature of the non-ball lettuce will adapt. The range is wider than that of lettuce. The seedling temperature is controlled at 16-20 °C during the day and 10 °C at night. The temperature varies greatly from season to season. Generally, the seedlings are raised from April to September, the seedling age is 25-30 days, and the seedlings are nursed from September to October. The seedling age is 30-40 days. Seedlings are raised from November to February, and the seedling age is 40 to 45 days. Seedlings in 2-3 true leaves. The seedling bed should be poured once before the seedlings, and the seedlings should be finely ground and fertilized as well as the seedlings. The seedlings were transplanted to the seedlings according to the seedling distance of 6 to 8 cm, and then watered immediately after the seedlings, and the covering was covered. After slow seedlings, proper water control is beneficial to hair roots and seedlings.
3.3.6 Colonization
When the seedlings have 5 true leaves, they can be planted. Before planting, the soil is fertilized, and the farmer's fertilizer is 3,500 kg and the phosphoric acid is two kilograms. The planting density is increased after spreading and the planting distance of the early maturing varieties is 25×. 3O cm, the mid-late maturity variety line spacing is 30 × 35 cm. It should not be too deep when planting, and it is better to not bury the leaves. When planting, try to protect the seedling roots to improve the survival rate. Spring, summer and autumn open field cultivation can be carried out by hollowing out seedlings and post-irrigation methods. In winter and spring, the cultivation of protected areas can take the method of water-stable seedlings, that is, first planting seedlings in rows within the raft, and shallow-covering soil after seedlings. Stabilize the seedlings, fill the water in the ditch, and then cover the soil to cover the soil. This can avoid adverse effects on the slow seedling due to the lowering of the ground temperature after irrigation.
4. Field management
4.1 dimming temperature control
1 light. Lettuce is a hi-light crop that requires plenty of sunlight for normal growth. In the cultivation of protected areas, attention should be paid to heat preservation and cold ventilation. The indoor temperature of the temperature (shed) should be controlled at 15-20 °C. When the temperature is high at noon on sunny days, the wind should be released in time, and the grass cover should be kept at night to make the temperature inside the shed not lower than 5 °C. The fog and snow should also uncover the straw curtains, let the plants receive the scattered light, carry out the light and action, and carry out short-term ventilation to prevent the occurrence of pests and diseases caused by excessive humidity, and also prevent the generation of harmful gases in the warm (shed) room.
2 temperature. Lettuce is semi-hardy-tolerant. The temperature of the vegetables is controlled at 18~20°C. The suitable temperature for seedling growth is 16～0°C. The suitable temperature for growing the outer leaves of lettuce is 18～23°C. The suitable temperature for product formation is 15～. At 20 ° C, low temperature is conducive to the formation of assimilation products, which is not conducive to the normal growth of lettuce.
4.2 watering
Watering is a key link in the cultivation of lettuce. The watering time and watering amount should be flexibly controlled according to the temperature and ground temperature of different growth periods. In greenhouse or greenhouse cultivation, watering is usually carried out 5 to 6 times throughout the growth period. Planting 3~5d for 1 time to slow down the seedling water, promote its slow growth, and tie new roots; after the first top dressing, it should be poured once, and the water should be poured once in the seedling stage, the fourth watering combined with the third top dressing In the middle of the ball, combined with the third top dressing and then watering once, generally do not top dressing watering in the later stage, so as not to cause decay and splitting balls, stop watering before harvesting.
4.3 cultivating and weeding
After planting and slowing down the seedlings, weeding and weeding should be carried out to enhance soil permeability and promote root development. It can also be used for weeding by the post-emergence selective herbicide "Gaisiling" chemical.
4.4 top dressing
Mainly based on the base fertilizer, the bottom fertilizer can not be topdressed in the early stage of growth. After the colonization, the lettuce is chased 3 times in the whole growth period. The first time is carried out about 15 days after the slow seedling, the urea is 10kg/667m, and the second top dressing is in the ball. In the early stage or during the rapid growth of the rosette period, the urea is 10kg/667m, and the second time in the middle of the yield formation, the urea is 8~10kg/667m, and the phosphorus and potassium leaf fertilizer can be sprayed.
5 pest control
The main diseases of lettuce are downy mildew, soft rot, viral disease, powdery mildew, etc.; insect pests mainly include leaf miners, aphids, and thrips. Most of the lettuce is used for raw food, and pests and diseases should be based on prevention. Comprehensive measures such as field management should be strengthened, and low-toxic, high-efficiency and low-residue pesticides should be selected for chemical control.
5.1 Disease prevention
5.1.1 nucleus pathogen, also known as sclerotium disease, occurs mostly at the base of the lettuce. Most of the susceptible parts were brown water-stained spots. Under high-humidity conditions, the diseased stem is softly rotted, and the surface is densely white with cotton-like hyphae. The pith is destroyed and rotted, or the longitudinal crack is dry. When the white mycelium grows vigorously, the black sclerotia of the mouse feces will be formed, and the infected leaves will wither, causing the whole plant to die. Control measures: Apply 50% of the WP 1500 times solution or 70% thiophanate-methyl WP 1O0o solution or 50% keering WP 1O0o solution at the initial stage of the disease. Once every 7 to 10 days, 2 to 3 times in a row. In the onset period, 70% pentachloronitrobenzene powder is used, and 0.25 kg of fine dry soil per acre is evenly spread on the inter-row floor.
5.1.2 Botrytis cinerea will be affected at the seedling stage and adult stage. In the seedling stage, the affected stems and leaves are watery and rot. Infected with adult plants, starting from the leaves near the ground, initially water-stained, then rapidly expanding, the stem base is rotted, and it is covered with taupe or gray-green mold layer. When the weather is dry, the diseased plants gradually die and die. White becomes gray and turns green. When the humidity is high, it festers upward from the base, and the petiole is dark brown. The disease is severe in warm, humid weather. Prevention and treatment methods: In the initial stage of the disease, use 50% more mildew 1000 times solution, or 50% speed Keling 1500 times solution, or 50% sponge antihypertensive powder 1500 times solution spray. According to the condition, spray once every 7 to 10 days, alternately use, and spray 2 to 3 times.
5.1.3 Soft rot mainly harms the soft and juicy tissues and leaves at the base or root of the stem, and the disease is serious. The diseased part is watery or translucent at first, and then becomes brown softened and rotted. Some occur from the base of the stem or the stem of the flesh, causing the whole plant to wilting. When the weather is dry, the decayed leaves are dehydrated and dried in a thin paper shape, tightly adhering to the leaf ball, and the diseased part seeps out the odorous mucus. Prevention and treatment methods: In the initial stage of the disease, 50% of the sensible ammonium wettable powder 1000 times solution, or agricultural streptomycin 4000 times solution spray. It can also be used to infuse the diseased plants and adjacent plants with 500 times of the original Kesong original powder, and the drug solution is 0.5 kg per plant. Alternate use, every 7 to 10 days, 2 to 3 times in a row.
5.1.4 brown spot disease mainly harms the leaves. Leaf spot shows two symptoms: one is water-stained at first, then gradually expands to round to irregular shape, brown to dark gray lesions, ranging from 2 to 10 mm in diameter; the other is dark brown lesion The edge is irregular, and the water-stained halo is seen on the periphery. When wet, the lesions are dark gray moldy, and in severe cases, the lesions melt together, causing the leaves to become brown and dry. Prevention and treatment methods: spraying 500 times of polysulfide suspension in the early stage of the disease, or 5o%~b hydantoic wettable powder 1500~ liquid, or 60% ethylphosphorus aluminum wettable powder 5oo times liquid, or 50% antibacterial 600 times Liquid, once every 10-15 days, 2 to 3 times in a row.
5.2 Pest Control
The main pests on lettuce are aphids, mites, Spodoptera litura, silver worms, and small tigers. Prevention and control of Spodoptera litura and Spodoptera litura can simultaneously treat both larvae and larvae. The small ground tiger can be sprayed with 2000 times liquid spray, or 50% phoxim with 0.20 to 0.25 kg per mu, and watered with 40 to 50 kg. Control aphids (mainly peach aphid and lettuce finger tube), you can choose 40% dimethoate emulsifiable oil 1000-2000 times liquid, or 50% dichlorvos EC oil spray control, pay attention to spray back when spraying; The control of aphids should be completed before the ball is formed, and it is difficult to control once the ball is formed.
6 Harvesting and storage
The harvesting standard of lettuce is not strict. It can be harvested at any time according to the needs of the market. The ripening period of the lettuce is very inconsistent. It should be dispersed and harvested. Generally, the ball in the outer edge of the ball is tight and the ball is relatively tight. Under pressure, the leaf ball can be harvested in time, and it is easy to rot or burst in the evening. It is generally harvested 40~60d after planting. At the time of harvest, cut off the ground and peel off the old leaves. Freshly harvested lettuce has high water content and is brittle. It can only be kept fresh for 1~2d at room temperature. It can be kept fresh for about 14d at a temperature of 0~3°C and relative humidity of 90%~95%, but the weight can be reduced by 15%. Precautions for harvesting: The maturity of lettuce is inconsistent and should be harvested in stages. Cut off from the ground with a knife, remove the old leaves, remove the soil, and keep the leaves clean. Harvesting quality: The body is neat, the leaves are fresh and tender, no disease spots, no insects, no dry leaves, no bad.
Specifications: (1) Chinese cabbage: no moss, no broken belly, single ball weighing more than 0.3 kg. (2) wrinkled leaf lettuce: no yellow leaves, rotten leaves, single weight 0.5 kg or more.
7 packaging
After trimming the ball, use a 0.03 ~ 0.05 mm low-density polyethylene film bag to wrap a single bag, 6 to 8 holes on the plastic bag to facilitate ventilation, the packaged leaf ball can be placed in a corrugated box, depending on the size of the carton Load and put in the cold stock. It can also be packed in bamboo baskets or plastic baskets. The product should be filled in the packaging container, but not too full or too tight to avoid crushing or bumping.
9 Breeding trends of lettuce varieties
Trends: 1. Mainly resistant to bacterial diseases. 2. With late twitch characteristics. 3. The direction of lettuce breeding. The qualitative nature of lettuce, the disease resistance to bacterial diseases such as spoilage diseases and spotted bacterial diseases, and the enhancement of late pumping are all major issues of breeding.
The above is all about today's lettuce cultivation technology. If you are planning to start growing lettuce, it is very important to choose the variety!
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