What kind of environmental conditions does broccoli need for growth and development
Broccoli, also called green cauliflower, tender-stem cauliflower, or green broccoli, is eaten for its crisp green head made up of tender, fat flower shoots and buds. It is not only tender, delicious and nutritious, but also highly adaptable, though its growth and development have relatively strict environmental requirements.
1. Light: Broccoli is not very strict about light, but during growth it likes ample light. When light is sufficient, the plants grow robustly and can form a strong vegetative body, which favors photosynthesis and nutrient accumulation, and makes the head compact and dense with a fresh green color and good quality. Too strong midsummer sunlight is also unfavorable for broccoli growth and development.
2. Temperature: Within the range of 5~25°C, the higher the temperature, the faster broccoli grows and develops. The optimum germination temperature is 20~25°C, and the optimum growth temperature at the seedling stage is 15~20°C. Broccoli has strong cold and heat tolerance. The optimum growth temperature at the rosette stage is 20~22°C, and the optimum temperature for head development is 15~18°C. When the temperature is above 25°C, head quality tends to deteriorate, but as long as it is not damaged by freezing, the head can still grow slowly at low temperatures of 5°C or even below. Different varieties and different seedling ages differ considerably in their temperature requirements, so variety selection is very important when cultivating in the same year.
3. Water: Broccoli needs a relatively large amount of water throughout its growth process, especially during vigorous leaf growth and head formation, when it must not lack water. Even short-term drought will reduce yield. Abundant rain at the seedling stage or excessively high soil moisture can easily cause diseases such as black rot and black spot. During head formation, soil moisture at about 70%~80% of field capacity is needed to meet growth needs.
4. Soil nutrients: Broccoli is not strict about soil conditions, but overly barren soil leads to poor plant development and low yield and quality, while overly fertile soil causes loose buds and hollow flower stems. Broccoli is suitable for planting in soil with good drainage and irrigation, a deep plow layer, loose and fertile texture, and strong water- and fertilizer-holding capacity. It adapts to a soil pH range of 5.5-8, but 6 is best. Broccoli needs sufficient fertilizer throughout its growth process, with an N, P, K ratio of 14:5:8. At the seedling stage, the demand for nitrogen is relatively greater, and after flower bud differentiation begins, the demand for P and K increases relatively. Note that during head development, broccoli also needs relatively large amounts of trace elements such as boron, molybdenum and magnesium. When boron is deficient, the center of the flower stem often splits, the head turns rusty brown and tastes bitter; when magnesium is deficient, the leaves turn yellow; when molybdenum is deficient, new leaves become whip-shaped and the head expands poorly. Therefore, applying an appropriate trace-element foliar fertilizer before budding will significantly increase yield and quality.