Detailed Explanation of Key Techniques for Autumn Cultivation and Management of Celtuce

Celtuce (scientific name: Lactuca sativa L. var. angustana Irish.), also known as lettuce, is a variety of the lettuce species in the Asteraceae family, Lactuca genus, that can form a fleshy tender stem. It is an annual or biennial herbaceous plant. Also known as stem lettuce, asparagus lettuce, green lettuce, and lettuce vegetable. Harvest period: January to April. It originated in Central or North China. The aboveground stem is edible; the stem skin is white-green, and the stem flesh is crisp and tender. Young tender stems are emerald green, turning white-green after maturity. The main edible part is the fleshy tender stem, which can be eaten raw, in cold dishes, stir-fried, dried, or pickled; the tender leaves are also edible. The stems and leaves contain lactucin, which contains lactucin. It tastes bitter and has an analgesic effect. Celtuce has strong adaptability and can be cultivated in spring and autumn or overwintering, mainly in spring cultivation, harvested in summer.

Morphological Characteristics of Celtuce

Celtuce is an annual or biennial herb, 25-100 cm tall. The root extends vertically downward. The stem is erect, solitary, with paniculate inflorescence branching in the upper part; all stems and branches are white. The basal leaves and lower stem leaves are large, undivided, oblanceolate, elliptic, or elliptic-oblanceolate, 6-15 cm long, 1.5-6.5 cm wide, with acute, short-acuminate, or rounded apex, sessile, with cordate or sagittate semi-amplexicaul base, with wavy or finely serrate margins; upper leaves gradually smaller, same shape as basal and lower stem leaves or lanceolate; the leaves below the paniculate branching and on the paniculate branches are very small, ovate-cordate, sessile, with cordate or sagittate amplexicaul base, with entire margins; all leaves are glabrous on both surfaces. Capitula are numerous or very numerous, arranged in a panicle at the stem and branch tips.

The involucre is ovoid in fruiting stage, 1.1 cm long, 6 mm wide; involucral bracts in 5 layers, the outermost broadly triangular, about 1 mm long, about 2 mm wide; outer ones triangular or lanceolate, 5-7 mm long, about 2 mm wide; middle ones lanceolate to ovate-lanceolate, about 9 mm long, 2-3 mm wide; inner ones linear-oblong, 1 cm long, about 2 mm wide; all involucral bracts have acute apex, glabrous outside. Ligulate florets about 15. Achenes oblanceolate, 4 mm long, 1.3 mm wide, compressed, light brown, with 6-7 fine veins on each face, apex acute forming a fine beak; beak filiform, about 4 mm long, nearly equal to the achene in length. Pappus in 2 layers, slender, slightly scabrous. Flowering and fruiting period: February to September.

Celtuce has a taproot system; after transplanting, many lateral roots develop, shallow and dense, mainly distributed in the 20-30 cm soil layer. The stem is shortened. Leaves are alternate, lanceolate or long-ovate, etc., light green, green, dark green, or purplish-red; leaf surface flat or wrinkled, margins entire or notched. The shortened stem gradually elongates and thickens as the plant grows; after flower bud differentiation at the stem tip, the stem thickens while the flower stem elongates, forming a club-shaped fleshy tender stem. The flesh color is light green, emerald green, or yellow-green. Conical capitulate inflorescence, flowers light yellow, each inflorescence has about 20 flowers, self-pollinating, sometimes cross-pollination also occurs. Achenes, dark brown or silvery white, with pappus.

Autumn Cultivation and Management Techniques for Celtuce

I. Seedling Raising and Transplanting

1. Seed Treatment

Before sowing, seeds should undergo low-temperature treatment. First, use low-temperature germination promotion: use 1 kg of water for 100 g of seeds, then add 4 drops of Atonik solution per 1 kg of water, soak for 6-8 hours, then rinse with clean water and drain. First wrap the drained seeds in a wet cloth, then wrap a semi-dry wet towel around the outside of the cloth, and place in the refrigerator (temperature below 16°C) cold storage compartment for 2-3 days.

2. Seedling Raising and Seedbed Preparation

First level and finely crush the seedbed. Use 10 g of Dexon per sq m diluted in water to drench and soak the seedbed thoroughly. Then broadcast the seeds on the bed surface at 5-8 g per sq m. Maintain moisture, build an arched shed; the height of the arched shed is best at 1 m-1.2 m. Then cover the arch frame with plastic film, keeping the film 6 cun (about 20 cm) above the ground, not touching the ground, to facilitate ventilation. Cover the plastic film with a shade net.

3. Seedbed Management

In management, the key point is preventing and controlling damping-off disease. Use Dexon at 1:500 dilution for root drenching. Keep the seedbed constantly moist. When sprinkling with water, it is best to do so when the weather is cool and the soil is cool.

4. Cultivation Management

① Apply basal fertilizer per mu: apply 10,000 jin of pig manure water per mu, or broadcast 5,000 jin of fermented chicken and duck manure, then broadcast 50 kg of compound fertilizer with 45% content over the whole field, and also broadcast 50-100 kg of lime over the whole field. After deep plowing, level and finely crush the soil, make beds and dig holes (row spacing 1.5 chi × hole spacing 1.2 chi), plant 3,500-4,000 holes per mu. After planting, immediately irrigate with 10% dilute manure water.

② Seedling promotion fertilizer: Apply seedling promotion fertilizer immediately 5-7 days after planting, using 5 kg of urea per mu diluted in pig manure water.

③ Open-plant fertilizer: When seedlings grow to 5-6 cun (about 17-20 cm), apply 1.5 kg of urea per mu diluted in pig manure water as top dressing.

5. Pest and Disease Control

Celtuce mainly suffers from soft rot, downy mildew, brown spot, and sclerotinia. Use a combined spray method for control. Method: one bucket of water (30 jin) with 3 g of streptomycin plus 15 g of Sumilex, plus 20 g of chlorothalonil, 20 g of DuPont Curzate, plus 3 mL of Atonik. When the field closes in, spray once every 10 days, for 3 consecutive sprays. Special note: boron fertilizer should be sprayed on the leaves. When seedlings grow to 6 cun (about 20 cm) tall, use 15 g of boron fertilizer per bucket of water (strictly avoid overuse) for foliar spraying. Apply once more when the field closes in.

II. Broadcasting

1. Seed treatment (same as for seedling raising and transplanting)

2. Apply heavy basal fertilizer, maintain soil moisture, and pay attention to cooling, drought resistance, and seedling protection.

3. Seed rate: 0.75 kg per mu.

4. From sprouting to harvesting small plants: 25-30 days. (Cultivation management and pest and disease control are the same as for seedling raising and transplanting.)

III. Field Management

Transplant at the appropriate age: seedlings can be transplanted when they reach 25 days of age. Transplanting is best done after 5 PM on sunny days or on cloudy days. The plant and row spacing for transplanted celtuce is 35*35 cm. Water thoroughly at transplanting, then water again the next morning to help the plants establish, until they have taken root. Early top dressing and watering: After seedlings have established, apply seedling promotion fertilizer early, using 1,000 kg of clear manure water per mu; at the rosette stage, apply 20-30 kg of urea per mu; when the field closes in, apply heavy fertilizer for stem base expansion, using 25-30 kg of urea per mu. After seedlings have established, water once to help them recover, and combine with applying manure to achieve both drought resistance and nutrient supplementation; at the rosette stage, water thoroughly; if water is lacking, bolting is likely. After the field closes in, if drought occurs, irrigate promptly; after the bed surface is moist, drain; in rainy weather, clear ditches promptly so that the field is dry after rain stops. Stop watering one week before harvest.

Early prevention of pests, diseases, and weeds: Diseases affecting celtuce include aphids, downy mildew, gray mold, etc. For aphids, use 40% dimethoate at 800x dilution or trichlorfon at 1,000x dilution; for downy mildew, use Ridomil at 600-800x dilution or 40% phosethyl-Al at 300x dilution; for gray mold, use 50% Sumilex or 50% iprodione at 1,000x dilution, spraying once every 7 days, for 2-3 sprays total. First cultivation: shallow, light, and even; second cultivation: slightly deeper, and earth up around the plants along the row direction; third cultivation: before the field closes in, combined with top dressing and earthing up, forming a semi-high ridge, which helps root absorption. Harvest early: Early autumn celtuce comes to market early; it coincides with the autumn slack season, so as long as celtuce approaches harvest standard, it can be harvested in batches for market. The harvest standard is when the heart leaves are level with the outer leaves. If not harvested in time, celtuce tends to bolt; you can remove the growing point and flower buds on sunny days to control top growth, increase nutrient flow back to the stem, promote tender stem thickening, and achieve quality marketing.