Introduction to Key Techniques for High-Yield Broccoli Cultivation
The market structure of the agricultural industry has gradually shifted from the original single focus on grain crops toward the cultivation of specialty vegetables. Specialty agricultural products will become increasingly popular in the market. How should the specialty agricultural product broccoli be developed and cultivated?
The basic techniques for high-yield broccoli cultivation are briefly introduced as follows:
I. Preface
(1) Brief Introduction to Broccoli
Broccoli, also known as green cauliflower or green broccoli, belongs to the Brassica oleracea variant of the Brassica genus in the crucifer family. Its edible parts are the green young flower stems and flower buds. It is rich in nutrients, containing protein, sugar, fat, vitamins and carotene, and ranks first among vegetables of its kind in nutritional content, and is known as the crown of vegetables. The nutrients in broccoli are not only high in content but also very comprehensive, mainly including protein, carbohydrates, fat, minerals, vitamin C and carotene, etc. According to analysis, every 100 grams of fresh broccoli florets contains 3.5 g—4.5 g of protein, which is 3 times that of cauliflower and 4 times that of tomato.
(2) Botanical Characteristics
Broccoli is a herbaceous plant of the crucifer family, with a well-developed root system and a thick and large main root crown. During the vegetative growth period, the stem is shortened, and the axillary buds are in a dormant state. After completing stage development, it bolts flower stems, and the axillary buds also gradually germinate. The leaves are long ovate or lanceolate. The main stem forms the main flower head, which is about 20 cm in height, about 14 cm in diameter, and about 400 g in weight. The flowers are compound inflorescences, complete, with green calyxes, and cross-pollinated. Broccoli's morphology and growth habits are basically similar to cauliflower, but its growth vigor is strong, and it has strong heat tolerance and cold resistance. The plant is tall. After growing 17 leaves, it bolts flower stems, and at the top grows densely clustered flower buds forming a flower head. The flower buds are blue-green, hence it is also called green broccoli. The leaf color is blue-green, gradually turning to dark blue-green, with increased wax powder. The petioles are narrow and long. There are two leaf shapes: broad-leaf and long-leaf.
II. Key Techniques for High-Yield Broccoli Cultivation
(1) Variety Selection
Based on variety characteristics and local climate conditions, in practice, we selected medium-maturing varieties as the main varieties for side-shoot production. Such as Youxiu, Lüfeng, etc.
(2) Environmental Requirements for Growth and Development
1. Light Broccoli is not very strict in its light requirements, but during growth it prefers sufficient light. When light is sufficient, the plant grows robustly and can form a strong vegetative body, which is conducive to photosynthesis and nutrient accumulation, and makes the flower head compact and dense, with a fresh green color and good quality. Excessive sunlight in midsummer is also not conducive to the growth and development of broccoli.
2. Temperature Within the range of 5—20°C, the higher the temperature, the faster the growth and development of broccoli. The optimum germination temperature is 20—25°C, and the optimum growth temperature during the seedling stage is 15—20°C. Broccoli has strong cold tolerance and heat tolerance. The optimum growth temperature during the rosette stage is 20—22°C, and the optimum temperature for flower head development is 15—18°C. When the temperature is higher than 25°C, the quality of the flower head tends to deteriorate, but as long as it is not damaged by freezing, the flower head can still grow slowly at a low temperature of 5°C or even below. Different varieties and different seedling ages have relatively large differences in the temperature requirements needed to complete vernalization, so the selection of varieties is very important for year-round cultivation.
3. Water Broccoli requires a relatively large amount of water throughout its growth process, especially during the period of vigorous leaf growth and flower head formation, when water shortage must not occur. Even short-term drought will reduce yield. Excessive rain during the seedling stage or excessively high soil moisture can easily cause diseases such as black rot and black spot. During the flower head formation period, the soil moisture needs to be about 70—80% of field capacity to meet growth needs.
4. Soil Nutrients Broccoli does not have strict requirements for soil conditions, but if the soil is too barren, the plant will develop poorly, and yield and quality will be low; while excessively fertile soil will lead to loose flower buds and hollow flower stalks. Broccoli is suitable for planting on loam and sandy loam with good drainage and irrigation, deep plough layer, loose and fertile soil texture, and strong water and fertilizer retention capacity. It adapts to a soil pH range of 5.5—8, but 6 is the best. Broccoli requires sufficient fertilizer throughout its growth process, and its N, P, K ratio is 14:5:8. During the seedling stage, the demand for nitrogen is relatively greater. After flower bud differentiation begins, the demand for P and K relatively increases. Note that during the flower head development process, broccoli also requires a relatively large amount of trace elements such as boron, molybdenum and magnesium. Therefore, applying an appropriate trace element foliar fertilizer before budding will significantly increase yield and quality.
(3) Land Preparation, Fertilization and Planting
Broccoli has strong growth vigor and a high fertilizer requirement, so sufficient base fertilizer must be applied in combination with land preparation. Generally, apply 5000 kg of high-quality barnyard manure per mu, 500 to 1000 kg of decomposed dried night soil, 30 to 40 kg of superphosphate, and 50 kg of plant ash. After spreading the base fertilizer, plough deeply and harrow finely, then level the land and make flat beds 1.3 to 1.5 m wide. Plant when broccoli seedlings have grown 5 to 6 true leaves. Generally, plant 2 rows per bed, with a plant spacing of 30 to 40 cm, and a planting density of about 2500 plants per mu. When planting, carry as much soil as possible and damage the roots as little as possible to reduce the seedling recovery period.
(4) Field Management
1. Intertillage and Weeding Before the plants close the rows, generally carry out intertillage 1—2 times, combined with clearing weeds, which is beneficial to growth.
2. Irrigation Broccoli has different water requirements at different growth stages. If drought or waterlogging occurs for a long time, it can lead to hollow flower stems, black hearts, cracked roots and other phenomena, affecting the product and quality. Generally, at planting time, water thoroughly to set the roots, and before survival, continuously water to help seedling recovery. After survival, appropriately reduce the number of waterings and combine with intertillage to promote root growth. During the vigorous leaf growth period and flower head formation period, increase the amount and frequency of irrigation. Prevent drought. In the rainy season, pay attention to drainage to prevent waterlogging.
3. Topdressing Broccoli requires a large amount of fertilizer and water. In addition to applying sufficient base fertilizer, timely topdressing should be carried out according to different growth periods. Topdressing should follow the principle of promoting at the early stage, controlling at the middle stage, and pushing at the late stage, that is, apply nitrogen fertilizer at the seedling stage to promote vegetative growth, control fertilization at the middle stage, and apply flower head fertilizer at the late stage. After planting and survival, use 1:5 diluted manure water to promote seedling growth, once a week. 25—30 days after planting, apply 20 kg per mu of urea or compound fertilizer in holes, and water after application to prevent drought and burning of seedlings. During the flower head formation period, apply a heavy topdressing once, that is, 25 kg of compound fertilizer and 20 kg of urea, to promote flower head enlargement.
(5) Pest and Disease Control
When broccoli flower heads begin to bud, spraying pesticides is prohibited. In the later stage of plant growth, there are more pests and diseases, and special attention should be paid to pest and disease control when harvesting side shoots. Main diseases in the later stage include black rot (for this disease, use 20% Dexon 1000-fold solution for control), root disease (use 50% chlorothalonil 1000-fold solution for control), and black fungus disease (use 58% black fungus clear 1000-fold solution for control). Main pests include diamondback moth (use 2.5% Decis 1500-fold solution for control) and cabbage caterpillar (controlled simultaneously when controlling diamondback moth).