Detailed Explanation of High-Yield Cultivation Techniques for Greenhouse Broccoli in Autumn and Winter
1. Variety Selection
Broccoli is a vegetable that prefers cool conditions, and generally any variety can be cultivated for the autumn-winter crop in a solar greenhouse. However, to improve economic returns, attention should be paid to combining early and mid-to-late maturing varieties, selecting varieties with strong plant growth vigor, dark green leaves with abundant wax, tight heads, small buds and large heads. According to trials: Dongfang Lubao, Yuguan, Lilu and Fanglu are early-maturing varieties, while Luling, Luxiu and Dongfang Luying are mid-to-late maturing varieties, and all can be cultivated for the autumn-winter crop in a solar greenhouse.
2. Raising Seedlings
Broccoli has a short seedling age (30-35 days), and depending on the specific situation, seedlings can be raised in mid-to-late October, with a large volume coming to market before Spring Festival. For raising seedlings, nutrient pots (10 cm × 10 cm) or the nutrient square method (8 cm × 8 cm) can be used. The nutrient soil is prepared with 8 parts fertile garden soil plus 2 parts fully decomposed chicken manure or sheep manure, sowing 2 seeds per hole, with a seeding rate of 20 grams per mu and a sowing depth of 0.5-1 cm. After sowing, water thoroughly once; after emergence in 2-3 days, remove weeds. The seedbed should be kept moist at all times. When 1-2 true leaves appear, thin the seedlings 1-2 times in good time, removing weak and overly dense seedlings. Keep the bed temperature at 20-30 degrees C; conversely, if the bed temperature is too low and the seedling age too long, small old seedlings will result, leading to short plants and reduced yield after planting. If the bed temperature is too high and humidity too great, the seedlings will become spindly and weak, leading to poor plant growth vigor and reduced yield. When the seedlings have grown to 5-7 true leaves at about 30-35 days, control fertilizer and water and ventilate to reduce humidity, hardening the seedlings for 3-5 days to improve the survival rate after transplanting.
3. Planting
Before planting, apply 4000 kg of high-quality farmyard manure, 15 kg of diammonium phosphate and 10 kg of ammonium nitrate per mu, mix evenly, plow, harrow finely and level, then form ridges for planting in wide and narrow rows of 70 plus 50 cm, that is, ridge surface width 70 cm, furrow width 50 cm, cover the ridge surface with 90 cm plastic film, plant spacing 40 cm, keeping 2750 plants per mu. After planting, apply fertilizer and water together, focusing on promoting growth, keeping the temperature at 8-24 degrees C to promote plant growth as quickly as possible and increase leaf area. After about 10 days, apply 15 kg of ammonium nitrate along with irrigation, and before the terminal head appears apply 6 kg of ammonium nitrate. After the head appears, keep the temperature at 15-18 degrees C; below 8 degrees C the head grows slowly, and above 24 degrees C the head becomes loose. During the entire plant growth period, the temperature should not exceed 32 degrees C.
4. Harvesting
When the head grows to 0.4-0.6 kg, with a diameter of 12-18 cm, dark green in color and tight and not loose, it can be harvested. Conversely, harvesting too early results in low yield and reduced quality, while harvesting too late causes bolting and flowering, losing edible value.
5. Pest and Disease Control.
Seedling damping-off. Treat seeds with 0.2% of 40% seed dressing dual powder or use it for soil treatment; when necessary, spray 25% metalaxyl wettable powder, or dress seeds with 0.2%-0.3% of 75% chlorothalonil wettable powder or 70% mancozeb powder.
Downy mildew. After finding the first infected plants, begin spraying 72% Kelu wettable powder at 800 times dilution, or 58% metalaxyl mancozeb wettable powder at 500 times dilution; where resistance has developed, switch to 69% Anke mancozeb at 1000 times dilution. Stop applying chemicals 7 days before harvest.
Soft rot. Avoid continuous cropping with Solanaceae and cucurbit crops and other cruciferous vegetables. Implement dark irrigation under film, control pests to reduce wounds. Dress seeds with Nongkang 751 at 1%-1.5% of the seed amount, spray streptomycin sulfate or 72% agricultural streptomycin soluble powder at 3000-4000 times dilution, once every 10 days, for 2-3 consecutive applications, and stop applying chemicals 3 days before harvest.
Cabbage caterpillars and aphids. Spray 50% pirimicarb wettable powder at 2000 times dilution and 25% omethoate fenvalerate at 1000 times dilution to control insects, applying 2-3 times during the whole growth period, with an interval of no less than 7 days between two applications. Stop applying chemicals 7 days before harvest.