Botanical and biological features
Broccoli (Brassica oleracea var. botrytis cymosa) is an annual plant belonging to the Brassicaceae family.
Broccoli is 2–3 times as rich in nutrients and vitamins as cauliflower. The biochemical composition of broccoli is extremely diverse: vitamins, microelements, essential amino acids; anti-sclerotic substances (methionine, choline) are among the broccoli protein components. The edible portion of broccoli is the head or crown similar to cauliflower curd but variable in color, the color ranging from green to bluish to purple to white.
Broccoli grows well on light, water-rich, deep soils rich in humus and available nutrients. This crop responds very well to organic and mineral fertilizers.
The best preceding crops are annual legumes, cucurbits, winter cereals, and onion. Light-soil fields which readily warm up in spring are chosen for broccoli cultivation.
Healthy uniform transplants are a key to early harvest. These should be 25–45 days old, depending on the growing technique, and have 3–6 well-developed leaves. The planting pattern is 70 õ 35 cm, with a seed rate of 50–70 seeds per 10 m2 of open ground. Cassette or potted seedlings become more readily established because no root system injuries occur during transplanting and, consequently, there are no diseased plants.
With autumn plowing, 500 g of nitroammophoska per 10 m2 (N 80, P2O5 80, K2O 80 kg of active substance per hectare) is applied to the crop. During the growing season, 2 to 3 supplemental fertilizer applications are made at a rate of 400 g of potassium nitrate and 150 g of ammonium nitrate per 10 m2 (N 100, K 180 kg of active substance per hectare). The fertilizer application rates are adjusted according to the soil nutrient status.
Systematic irrigation is a crucial factor in the cultivation cycle. During the growing season, 5–8 irrigations are given to the crop with a water application rate of 350–400 l per 10 m2 (350–400 m3/ha) per irrigation. Combining drip irrigation with application of water-soluble fertilizers through the drip irrigation system (fertigation) is a highly efficient technique resulting in a more uniform moisture and fertilizer distribution in the root zone, more efficient water use, less soil compaction, and no soil crust formed. Readily soluble mineral fertilizers are given with each water application.
Broccoli can be grown from early spring till late autumn. It can also be used as a second double crop after early-harvested preceding crops.
Nicely shaped and well-domed heads of broccoli do not shade the frame. The plant shows excellent side shoot development after the main head is cut, giving an additional yield of small heads.
Harvesting is normally begun prior to bead opening (while the beads are still tightly closed). The head is cut along with a portion of stem 10–20 cm long which is also used for food.
Control measures: on discovering the first signs of infestation, sprays with insecticides such as Sumi-alpha, Zolone, Sherpa, Karate, Actellic, Volaton, etc. should be made systematically in cycles of 7-10 days. Considering that the cabbage leaf has a thick wax coating, it is advisable to admix adhesives (OP-7, skimmed milk or household soap in amounts of 30-50 g per 10 l of water) into the spray solution.
Among the diseases attacking brassicas, the most damaging are Black rot, Soft rot and Fusarium wilt. The control measures are similar to those used in white cabbage.