BROCCOLI PRODUCTION

BROCCOLI  (Brassica oleracea var Italica) 

Broccoli is a cool-season crop that, it is a member of the cabbage family.

Broccoli contains 60% vitamin C. Cooked broccoli has 125% vitamin C more than a fresh orange depending on preparation method. It also contains the yellow carotenoid, iron, vitamin E and K. It is a good source of calcium, having as much as milk, although the form found in broccoli is easier to digest. The dark green leaves attached to the heads are very nutritious and flavourful and can be used in stir-fry, soups, or in mixed vegetables. 

Marketing

The broccoli market has steadily grown in Kenya, mainly due to improved eating habits by the middle and upper income communities.  Consumption is also high in various institutions offering catering services and restaurants. It is sold in supermarkets, whole sale markets and retail venders
Ecological Requirements
Altitude

Broccoli is best suited to cool high altitudes regions.
Rainfall

A mean annual rainfall of 800-1000mm is required for broccoli production. The plants should be supplied with sufficient water without creating waterlogged soil. Stress from inadequate water decreases the quality and quantity of the broccoli harvest.
Soils

Broccoli can be grown on a wide range of well drained soils with high organic matter content. Sandy loams are preferable for early crop, while later crops are likely to give highest yields on silts, silt loams, or clay loams. Soil crusting can be a problem with broccoli on heavier soils. A pH of 5.5- 6.5 is ideal for optimal yields. 

Temperature

•  Broccoli grows best at temperature range of 16-18 ⁰ C. The upper limit for broccoli growth is 25-28 ⁰ C. The plant looses quality when the temperatures exceeds 28 ⁰ C.
• High temperature cause broccoli heads to become loose and branchy and may favor the development of bracts (leaf like structures) in the heads. 
•   Broccoli heads turn yellow and flowers rapidly in hot weather. Rapid growth at high temperatures results in leafy heads, loose clusters and premature opening of flower buds.

Categories of broccoli
Broccoli can come in a variety of colors- green, yellow-green and even purple. There are 3 categories of broccoli:
Sprouting broccoli

This is ready to harvest after producing the thick heads. It may have green, purple, yellow or white flower heads.
Romanesco

This matures later in the year and displays yellowish–green, with spirals that form multiple, pointed heads that group together.
Calabrese

An annual harvested in warm weather. The heads can be green or purple. It takes the name from the Italian meaning, “from Calabria”. Calabrese should be eaten before the buds turn yellow and flower emerges.

Some popular broccoli varieties in Kenya

1.   Green sprouting- Matures in 60 days, has with medium large sprouts. It produces compact heads with exquisite flavour and has an abundance of fleshy stalks with flowering shoots over a long period.

2.   Dandy Early No. 32 F1 Hybrid- Matures in 92 days, vigorous variety tolerant to black rot and downy mildew. The heads are firm, dome shaped, about 10 -12 cm wide and 6 cm high. It is solid and flattish when young with medium sized grains.

3.   Early Green F1 Hybrid- Matures in 85 days, has good quality heads. It has a typical single head and no side shoots. The heads are solid and regularly shaped. It is mushroom shaped with uniform bluish green colour.

4.   Stalto F1- Matures in 60 days, High producer with uniform coloured head 

5.   Ritardos- Matures in 65 days; it is tasty with unique dark foliage 

6.   Heritage- Matures in 60 days; it produces steady yield when using irrigation.

1. Skiff F1- Matures in 60 days has compact heads with a blue green colour.

Starting Broccoli farming

•  Plan well for the market requirement.

• It is very important to understand the growth requirements especially the required temperatures for production

• Select varieties suitable to your local conditions and market requirement.

Propagation

Broccoli can be established in the field by direct-seeding or by transplanting. Direct-seeding, however, holds a greater degree of risk because of possible crusting of the soil surface. This impedes seedling emergence.

Nursery Establishment

• The nursery beds should be raised. Beds should be made 1m wide for ease of operation and of convenient length depending on the area to be planted.

• Sterilize the beds before seeding to reduce the chance of disease transfer to the field. 

• During the preparation of nursery, addition of 100g/m² or TSP or DAP is necessary.

• The seeds should be drilled in the seedbed at a spacing of 10-15 cm between the rows.

• The seedbed should be covered with dry grass and watered immediately. Daily watering is necessary to keep the seedbed moist. After germination of the seeds, the grass cover should be removed and thinning done to leave a spacing of 2-3 cm between the plants.

• While in the nursery, about 60g/m² of CAN should be applied weekly in irrigation water (irrigation can be done using a watering can).

• Pests and diseases should be controlled as the need arises. Over shading and over watering should be avoided as it predisposes the seedlings to mildew attacks.

Transplanting

·         The seedlings should be transplanted when they are 15cm tall with at least 4 true leaves. Water the seedbed before uprooting the seedlings to reduce root damage.

·         During transplanting, phosphatic fertilizers e.g. DAP or TSP should be added into the soil at 20g per hole. Transplanting should be done early in the morning or on a cool afternoon.

Spacing

During field establishment, seedlings are spaced at 60cm between rows and 45 cm from plant to plant.

Seed rate- 120g/ha

Direct sowing

·         Plant rows should be spaced 60 - 90 cm apart, 8 cm between plants and 1.5cm deep. 

·         When seedlings are about 4 to 6 weeks old, thin seedlings to 45 - 60 cm apart in between plants. 

·         Thinned seedlings can be transplanted to another part of the garden. 

Manure Application

Prior to planting, up to 40tons/ha of manure should be applied depending on the soil organic matter content.

Fertilizer Application

1. 20g per hole of DAP or TSP added into the soil during transplanting.

1. Plants are Top dressed with 20g of CAN per plant 2 weeks after transplanting and another 20-40 g/plant 4 weeks after transplanting.

1. Micro elements should be applied according to soil tests to avoid toxicity. However magnesium and Boron are essential elements for broccoli growth. Deficiencies of magnesium and boron are shown by yellowing of leaves and hollow hearts respectively. 

Irrigation

Provide consistent soil moisture with regular watering, especially in dry conditions. Some varieties of broccoli are heat tolerant, but all need moisture. Keep soil moist but do not wet the developing heads. Reduce watering as the heads approach maturity and harvest.

Weeding

Broccoli roots are very shallow; hence care should be taken while weeding. Mulching can be done to suppress weeds and to keep soil temperatures down. Keep the field free of weeds until the crop covers the ground.

Pests and Diseases

The broccoli s attacked by pests that attack vegetables in the cabbage family.

Major pests include diamond back moth, cabbage looper, cabbage sawfly, cabbage aphids and cutworms.
Control

• Control using recommended insecticides

• Timely weeding to remove host plants

• Serious diseases which should be controlled include black rot, blackleg ring spot, downy mildew.

• Downy mildew is a severe problem in broccoli growing in Kenyan high altitudes. Yellow patches on leaves are usually caused by moist weather. Keep leaves as dry as possible

• Clubroot is a fungal disease in the soil that causes wilting of plants may be due to this fungus.  Roots are twisted and misshapen. Uproot the entire plant including all roots and root tendrils. Do not compost the plants.

Disease control

Crop rotation, use resistant varieties, nursery and field hygiene are the major control measures against diseases
 

Physical disorders

Broccoli are sensitive to environmental conditions. Any condition, which results in a prolonged reduction of vegetative growth during early stages of plants development, can trigger the onset of buttoning (premature formation of small head when the plant is immature).
 

Buttoning 

• Buttons can form when the plant are grown below 10 ⁰C in the bed and are exposed to periods of cool weather following field setting.

• Lack of nitrogen and other nutrient stresses as well as competition from weeds, insects or that slow vegetative growth can promote buttoning.

• Transplants that are older and less vigorous are more likely to button than young, fast growing plants.  
• Bare rooted plants, which have been exposed to drying or water stress immediately following transplanting, are also more likely to button.

Buttoning can be prevented by:

• Maintaining a steady, moderate rate of growth in the plant bed.

• Setting young, healthy transplant that have not initiated head formation

• Setting plants under favourable condition for growth and irrigating to relieve moisture stress.

• Maintaining rapid growth, particularly for the first few weeks after setting by using Nitrogenous topdressing fertilizer.

Premature flowering

• Premature flowering is usually attributed to periods of hot weather immediately before heads are harvested. However high temperatures more than30 ⁰C, 7-8 weeks after planting have a greater influence on tendency to flower than high temperatures the week before harvest.

• Irrigation during high temperatures could reduce potential loss.

Nutrient deficiency 

• Magnesium deficiency results in chlorotic marbling and tinting of leaves.

• Iron deficiency shows chlorosis of leaves beginning as a chlorotic mottling.

Nitrogen deficiency -bottom leaves turn yellow and the problem continues toward the top of the plant, (the plants need a high nitrogen but low phosphorus fertilizer).
 

Harvesting

• Broccoli is ready for harvesting 60-95 days from germination depending on variety. Harvest broccoli when the buds of the head are firm and tight before the heads flower.

• Mature broccoli heads are still compact (tight) and have no yellow buds.

• Over mature heads have a woody outer stem, may show yellow flower colour, and have looser flower cluster.

• The heads should be harvested when the flowers are deep green, fully grown but not over mature.

• For best taste, harvest in the morning before the soil heats up.

• When harvesting, cut heads with 8-10 cm of the stem.

• The plants should be harvested into clean containers.

• Cool broccoli as soon as possible after harvesting. The most feasible method of pre-cooling is to place the broccoli in ice water.

Yields

·        The yields range from 12-17 tons/ha depending on variety. Once the first head harvested other new ones start sprouting and unlike cabbages which are harvested once.

Post harvest

Broccoli is highly perishable. The respiration of freshly harvested broccoli is very high and it is therefore necessary to hydro-cool very soon after harvest and to keep it cool. Hydro-cooling is the process of spraying or immersing vegetable in chilled water.

Storage

• Broccoli should be stored unwashed, in loose perforated bags in the refrigerator. If left unrefrigerated, the heads quickly become woody and fibrous. Wet broccoli can become flaccid and soggy and also support the growth of microorganisms, so it is recommended to wash just before eating.

• If washed before storing, the heads should be thoroughly dried.

• Store broccoli heads at 0-4 ⁰C with relative humidity 95-100% to maintain its fresh green colour and vitamin C content. Broccoli can be stored for 10-14 days under the above conditions.

•  Broccoli should not be stored with fruits, such as apples, bananas and pineapples. Which produce substantial quantities of ethylene, because the gas accelerates yellowing of buds.

Packaging

Package broccoli flowers or leaves in firm cardboard boxes or plastic crates. The package should not exceed 20kg in weight.

Challenges in production

• Pest and disease management can be a challenge in production leading to poor quality produce, thus it requires adequate skills and timeliness in management.

• At room temperature, harvested broccoli converts its sugar into a fiber called lignin. 

• In the absence of cool storage leads to lose in quality and value of produce

Advice to potential growers

• Broccoli Market mainly in restaurants and the upper and middle income areas therefore, it is important to produce quality broccoli heads to maintain the special market segment. 

• Maintaining the right conditions for production and storage can enable growers to achieve the desired production standards