Field management techniques for broccoli at each growth stage

Broccoli is an annual or biennial herbaceous plant native to the eastern Mediterranean coastal region. It is cultivated only in small amounts in China, mainly for use in Western cuisine. Broccoli is rich in nutrients, containing protein, sugars, fats, vitamins and carotene, and ranks first among vegetables of its kind in nutritional content, and is known as the crown of vegetables.

I. Management during the seedling recovery stage

Management during this stage mainly involves cooling and moisture retention to promote early seedling recovery. In addition to using shade nets to build shelters for shading and cooling, water must also be sprinkled once each in the morning and evening. To prevent underground pests from biting through the seedlings, Mireer is evenly scattered on the soil surface at transplanting. About 7 days after transplanting, a light application of human feces and urine or a 2%-3% urea water solution is applied to promote plant growth. To prevent and reduce the occurrence of diseases, about 10 days after transplanting, one spray application of 75% chlorothalonil 600-fold solution or 50% carbendazim 600-fold solution is made.

II. Management during the rosette stage

This stage is the period of vigorous vegetative growth for broccoli, and sufficient fertilizer and water must be provided so that stems and leaves grow quickly, laying a good nutritional foundation for achieving high yields. During this stage, topdressing is needed 2 times. The first topdressing is when the plants begin to grow rapidly (about 15 days after transplanting), using a small hoe to open holes between the plants and apply urea, about 15 kg per mu; the second topdressing is carried out before the plants close the rows, when the heart leaves begin to show a twisting-heart shape (about 30 days after transplanting), combining weeding with opening shallow furrows between the rows, applying fertilizer and then hilling soil, applying 20-25 kg of compound fertilizer per mu, or 25 kg of peanut bran. Where conditions permit, it is best to apply human feces and urine once every 7-10 days during this stage. In the early rosette stage, watering should be sufficient to meet the needs of rapid plant growth and development; after the plants have formed a full rosette, watering should be appropriately controlled to promote underground root development. Side branches that appear during this stage should be removed promptly to promote the formation of the main curd. At the same time, attention should be paid to the prevention and control of diseases and pests, especially the damage caused by diamondback moth (commonly known as hanging-silk worm), cabbage white butterfly (commonly known as cabbage caterpillar), black rot and soft rot. Diamondback moth can be controlled by spraying 5% fipronil 3000-fold solution or 1% insecticidal substance 3000-fold solution from the peak hatching period of eggs to the 2nd-instar larval stage; cabbage white butterfly can be controlled by spraying Bt emulsion 1000-fold solution, or fenvalerate 1500-4000-fold solution; in the early stage of black rot and soft rot, agricultural streptomycin at 200 mg/L, or chloramphenicol at 200 mg/L, or 75% chlorothalonil 600-fold solution, or 77% copper hydroxide 500-800-fold solution can be sprayed alternately for control.

III. Management during the curd-forming stage

To promote the transformation from vegetative growth to reproductive growth and facilitate curd formation, nitrogen fertilizer should be appropriately controlled during this stage, with combined application of phosphorus and potassium fertilizers and trace fertilizers such as boron and molybdenum. At the beginning of curd formation (40-50 days after transplanting), a heavy fertilizer application is made, applying 15 kg of potassium chloride and 15 kg of compound fertilizer per mu. To reduce yellowing of the curd surface and hollow stems, and to delay plant senescence, during the curd-forming stage a 0.5% borax and 0.5% ammonium molybdate solution is sprayed on the leaves, about once every 1 week, for 2-3 consecutive sprays. Throughout the curd-forming stage, field soil should be kept moist, and diseased leaves and old leaves should be removed promptly, with disease and pest control carried out. For cultivation that also harvests side curds, 3-4 healthy side flowering branches are retained per plant, and the remaining side flowering branches should be removed.

IV. Management during the peak harvest stage

During this stage, attention should be paid both to promptly removing diseased leaves and old leaves to facilitate ventilation and light penetration and promote nutrient accumulation in the curd, and to controlling moisture to prevent excessive humidity, which can cause disease and curd rot. In acid rain or heavy fog weather, water should be sprinkled promptly to wash away fog moisture and acid rain, so as to reduce curd decay. The suitable harvest period for broccoli is relatively short. If harvested too late, the curd becomes loose, the buds turn yellow, and quality declines; but if harvested too early, the curd is small and yield is low. Generally, the suitable harvest time is when the buds feel somewhat loose to the touch or the buds at the edge of the curd are slightly loose, and the curd surface is tight, flat and free of unevenness. Broccoli harvesting is best done in the early morning or evening on a sunny day. When harvesting, cut off the curd together with about 10 cm of tender fleshy stalk, place it in a shaded and cool place, and package it for market as soon as possible. If it cannot be marketed in time, it must be quickly stored at low temperature. For cultivation that also harvests side curds, topdressing should also be applied once after the main curd is harvested, about 15 kg of compound fertilizer per mu, and the side curds should be harvested when they grow to about 5 cm in diameter.