Green Peak Broccoli is an exceptional early-maturing and heat-tolerant variety originally sourced from Jiangsu Zhengda Agronomy Seedling Co., Ltd. This premium-quality variety is particularly well-suited for fresh exports. Below is a detailed description of the cultivation methods for summer and autumn.
(I) Characteristics
Green broccoli belongs to the main spherical hybrid category, showcasing strong growth potential and excellent heat tolerance. Even when planted at temperatures exceeding 30°C, it can still yield tightly packed flower heads. During the summer and autumn seasons, the entire growth cycle spans approximately 80 days. The plant reaches a height of 65 cm with a spread of about 55 cm, making it ideal for dense planting. Each plant typically has 16-17 outer leaves, featuring a mix of light green, semi-silky, and lanceolate foliage. The primary flower head is almost hemispherical, with a diameter of roughly 13 cm and a weight of around 280 grams. The florets are coarse yet orderly, and the flower heads are a vibrant green, making them perfect for summer and autumn cultivation and fresh export. Flower heads develop rapidly and can be harvested within about 50 days post-planting. This variety demonstrates increased resistance to root rot and downy mildew.
(b) Cultivation Tips
1. Seedling Raising and Management
In the Yangtze River basin, green broccoli is predominantly grown during summer and autumn, with sowing typically occurring in mid to late July. This period is marked by high temperatures and rainfall, resulting in prolonged seedling growth and numerous pest issues. Therefore, all seedlings are cultivated, with robust seedlings being critical for successful cultivation.
(1) Nutrient Block Nursery: Choose a plot with loose soil, previously free of cruciferous crops, for the seedbed. For every 15 acres of land, prepare approximately 400 square meters of seedbed. Apply 500 kg of decomposed organic fertilizer prior to planting, mixing it with phoxim-treated soil. Construct raised beds that are 1.2 meters wide and 20 cm high. After leveling, create nutrient blocks with a diameter of 6-8 cm, followed by bottom watering. Place one seed in each block and cover it with 1 cm of finely sieved soil.
(2) Cooling and Protecting Seedlings: Immediately after sowing, cover the seedbed with a single layer of plastic film to retain moisture. Afterward, cover the film with a straw curtain or 90% shade netting (straw curtains provide better cooling). Maintain the temperature around 25°C to promote germination. After 2-3 days, inspect the seedlings. Once 80% of the seeds have sprouted, remove the mulch and shade nets in the evening. Additionally, set up a shaded structure 80 cm tall over the seedbed, using the shade net to cool the area from 10 am to 3 pm. On cloudy days, avoid covering the seedlings. Always cover the seedbed with plastic sheets before storms to shield against heavy rains.
(3) Seedling Care: Do not water broccoli before the heart breaks to prevent the formation of leggy seedlings. Water sparingly when the topsoil of the seedbed dries out, ensuring thorough hydration without overwatering. Typically, seedlings should receive 2-3 thorough waterings. Thin human manure can be applied as a foliar feed. Remove weeds manually as needed. Ensure the seedling period does not exceed 30 days, as longer durations can affect the size of the flower heads.
2. Base Fertilization and Proper Spacing
Select sandy loam soil with good drainage and irrigation for planting. Prior to planting, apply 2000-3000 kg of organic fertilizer and 30 kg of high-concentration compound fertilizer per mu, along with 1 kg of boron fertilizer (boron deficiency can lead to hollow bulbs, and 10-12 leaves may also be sprayed). After fertilizing, cultivate and till the soil, arranging plants in high ridges in double rows, spaced 1 meter apart. Plant density should be 3333 plants per acre, with a spacing of 40 cm between plants. Immediately after planting, water the roots to shorten the seedling adjustment period.
3. Field Management
(1) Fertilizer Management: Following base fertilization, apply three top-dressings. The first occurs 1-10 days after planting, using 5 kg of urea and diluted human manure. Around the 10-12 leaf stage, apply 15 kg of urea and 10 kg of high-concentration compound fertilizer. When the flower buds reach the size of a ping pong ball, apply another 5 kg of urea.
(2) Water Management: Monitor soil moisture levels regularly and irrigate promptly during dry spells. In summer and autumn, water should be applied in the evening when temperatures are cooler, and fields should remain free of standing water the following day. After rainfall, ensure proper drainage and cultivate the soil to enhance aeration and promote root development.
(3) Pest and Disease Control: Focus on preventive measures. Besides proper water management, remove diseased lower leaves in the later stages of growth to improve ventilation and light penetration. Starting 15 days after planting, alternate treatments such as 72.2% propineb at 600x dilution, 75% chlorothalonil at 500x, or 40% ethylphosphonate at 200x every 10-15 days to control downy mildew. Use 72% streptomycin sulfate at 3000x or 77% copper oxychloride WP at 1500x to prevent root rot. For pests like cabbage worms, diamondback moths, and aphids, apply 2.5% vegetable pyrethrum at 1000x, 5% fipronil at 1500x, or 0.3% matrine at 3000x to control Pieris rapae and Plutella xylostella. For aphids, use 2% imidacloprid at 2000x or 50% thiamethoxam at 2000-3000x.
4. Harvesting and Post-Harvest Handling
Harvest the flower heads in batches as they mature, completing the process before and after 9 am. Cut the heads along with tender stems measuring about 15 cm below the flower head, leaving 2-3 leaflets surrounding the head, and remove any remaining leaves. Place the heads in specialized boxes for transport and sale. Ensure proper packing to avoid compression. Avoid delays post-harvest to prevent flower yellowing and water loss. After harvesting, trim the product slightly, immediately pre-cool it (soak in 0°C water), and store it in a low-temperature, high-humidity environment at 0°C and 95%-100% relative humidity. This storage method allows the product to last for 8-10 days.
By adhering to these cultivation guidelines, growers can maximize yields and maintain the high quality required for fresh export markets.
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