KILIMO SASA: Tomatoes production

Tomato is one of the most highly consumed vegetable in Kenya.
It is grown for fresh market, processing and export market.
The information covered here includes:

Ecological Requirements
Tomato Varieties
Husbandry practices
Pests and nutrients disorders
Diseases
Harvesting and Post Harvest Handling
Marketing, Gross margin and Value addition

Ecological Requirements

Tomato is fairly adaptable and grows well in warm conditions. It requires optimum temperatures of 20 -25 degrees C during the day and 15 -17 degrees C at night.
Requires moisture of about 600mm well distributed throughout the growing season.
Requires well drained soils, light loam with high organic matter content and pH of 5 -7.5.

Principles of Green House Technology:

A greenhouse (also called a glasshouse) is a building where plants are grown under controlled micro environment. These structures range in size from small sheds to very large buildings. A miniature greenhouse is known as a cold frame.
A greenhouse is a structure with different types of covering materials, such as a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming visible solar radiation (for which the glass is transparent) from the sun is absorbed by plants, soil, and other things inside the building. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall.

Purpose of the Green House

a) To promote tomato growing in the cooler areas
b) To promote the growing of tomatoes throughout the year in both cool and warm areas

Justification of the Green House Tomato Growing

a) Growing tomatoes in a green house reduces disease infection and also raises the temperature. Tomatoes require an optimum temperature range of 20-25 0C during the day and 15-17 0C at night.
b) In the green house, tomatoes may be fed with carbon dioxide easily. This increases yield and enhances quality.
c) Currently, most farmers grow tomatoes during the dry seasons, under irrigation.
In the green houses tomatoes can be grown all the year round

Advantages of a Green House

a)      Higher yields can be realized/intensive production per unit area
b)      High quality produce
c)      Minimized cases of diseases
d)     Market timing for optimum profit
e)      Production levels may be maintained all the year round
f)       Other warm season crops may be grown throughout the year

Other Crops Recommended in the Green House

a)      Coloured Capsicum varieties e.g. red, yellow etc.
b)      Cucumbit family e.g. Cucumbers, courgettes
c)      Onions e.g. bulb onions,
d)     Garlics
e)      Herbs and Spices e.g coriander, parsley, celery
f)       Brinjals (egg plants)

Green House Methodology:

Types of Green Houses

Classification According to Size

a) Cold frame (miniature) green house for subsistence (less than 15×7 m)
b) Economic unit - 15mx7m
c) Commercia l- more than 15×7m

Classification according to lifespan and materials used

Frames can be covered with glass, rigid fiberglass, rigid double-wall plastics, or plastic film
a)      Permanent green houses
Metal frame-work and covered with glass with automated cooling/heating systems e.g. in research stations
b)      Semi permanent green houses
Metal frame-work but covered with plastic film/paper
Recommended for established farmers
c)      Temporary green houses
Wooden frame-work covered with plastic film /paper.
This is recommended for small scale farmers.

Classification according to structural shape of frame

A greenhouse can be attached to a house or garage; it can be a freestanding structure or gutter connected

a) Attached Greenhouses

i) Lean-to. A lean-to greenhouse is a half greenhouse, split along the peak of the roof, or ridge line (Figure 2A), Lean-tos are useful where space is limited to a width of approximately seven to twelve feet, and they are the least expensive structures.
The disadvantages include some limitations on space, sunlight, ventilation, and temperature control. The height of the supporting wall limits the potential size of the lean-to. The wider the lean-to, the higher the supporting wall must be. Temperature control is more difficult because the wall that the greenhouse is built on may collect the sun’s heat while the translucent cover of the greenhouse may lose heat rapidly. The lean-to should face the best direction for adequate sun exposure.
Finally, consider the location of windows and doors on the supporting structure and remember that heavy rain might slide off the roof of the house onto the structure.

ii) Even-span. An even-span is a full-size structure that has one gable end attached to another building (Figure 2B). It is usually the largest and most costly option, but it provides more usable space and can be lengthened. The even-span has a better shape than a lean-to for air circulation to maintain uniform temperatures. An even-span can accommodate two to three benches for growing crops.

iii) Window-mounted. A window-mounted greenhouse can be attached on the south or east side of a house. This glass enclosure gives space for conveniently growing a few plants at relatively low cost (Figure 2D). The special window extends outward from the house a foot or so and can contain two or three shelves.

b) Freestanding (detached) Structures:

Freestanding greenhouses are separate structures; they can be set apart from other buildings to get more sun and can be made as large or small as desired (Figure 2C).
You can also access a multi-media information on growing of tomatoes within a greenhouse via this link Greenhouse tomatoes growing.

Shapes of Frames:

The following are several common shapes of frames;

Quonset- sidewall height is low, which restricts storage space and headroom.
Gothic: The gothic frame construction is similar to that of the Quonset but it has a gothic shape (Figure 3). Wooden arches may be used and joined at the ridge. The gothic shape allows more headroom at the sidewall than does the Quonset.
Rigid-frame: The rigid-frame structure has vertical sidewalls and rafters for a clear-span construction. There are no columns or trusses to support the roof. Glued or nailed plywood gussets connect the sidewall supports to the rafters to make one rigid frame. The conventional gable roof and sidewalls allow maximum interior space and air circulation. A good foundation is required to support the lateral load on the sidewalls.
Post and rafter and A-frame: The post and rafter is a simple construction of an embedded post and rafters, but it requires more wood or metal than some other designs. Strong sidewall posts and deep post embedment are required to withstand outward rafter forces and wind pressures. Like the rigid frame, the post and rafter design allows more space along the sidewalls and efficient air circulation. The A-frame is similar to the post and rafter construction except that a collar beam ties the upper parts of the rafters together.
Ridge and furrow (gutter connected) green houses:

A green house with more than three bays (multi gutter connected) is called a ‘range’

The lowest cost per square foot of growing space is generally available in a freestanding or even-span greenhouse that is 17 to 18 feet wide. It can house a central bench, two side benches, and two walkways. The ratio of cost to the usable growing space is good.
When deciding on the type of structure, be sure to plan for adequate bench space, storage space, and room for future expansion. Large greenhouses are easier to manage because temperatures in small greenhouses fluctuate more rapidly. Small greenhouses have a large exposed area through which heat is lost or gained, and the air volume inside is relatively small; therefore, the air temperature changes quickly in a small greenhouse.

Growing Media

Sawdust/Sand/Manure at the ratio of 3:1:1 Or
topsoil/sawdust/manure/sand/charcoal dust at the ratio of 10:10:6:5:3 Or
top soil/sand/manure at ratio of 3:1:1
Note: A lorry of each (7 tons) is required
Other materials used as growing media are: Peat, perlite,bark,vermiculite

Sterilization of Growing Media:

Water the media in the beds thoroughly and then cover with black polythene paper for three-four weeks to eliminate weed seed, disease pathogens and insect pests in the growing media. The media also becomes cured and compacted ready for planting.

Location of a Green House:

Factors to consider while locating green house;

a)      Sunlight direction: The greenhouse should be located where it gets maximum sunlight. The first choice of location is the south or southeast side of a building or shade trees. Sunlight all day is best, but morning sunlight on the east side is sufficient for plants. Morning sunlight is most desirable because it allows the plant’s food production process to begin early; thus growth is maximized. The next best sites are southwest and west of major structures, where plants receive sunlight later in the day. North of major structures is the least desirable location and is good only for plants that require little light.
b)      Light requirements of the plants to be grown;
c)      Shade: Evergreen trees that have foliage year round should not be located where they will shade the greenhouse because they will block the less intense sun.
d)     Drainage: Good drainage is another requirement for the site. When necessary, build the greenhouse above the surrounding ground so rainwater and irrigation water will drain away. Access to the greenhouse should be convenient for both people and utilities.
e)      A workplace for potting plants and a storage area for supplies should be nearby.
f)       Prevailing wind
g)      Topography of the area

Basic Structural component of a green house:

Framing materials:

Greenhouses may be constructed from several different materials. Among the most popular are aluminum, steel and wood. Of these three, aluminum is by far the most economical and longest lasting.

Covering materials:

Greenhouse coverings include long-life glass, fiberglass, rigid double-wall plastics, and film plastics with 1- to 3-year lifespan. The type of frame and cover must be matched correctly.

Size

(1 Bank/Bay/Unit Dimensions:- ( 15 m x 7 m (or 50 ft x 23 ft) = 105 m2 or 1150 ft2 ( minimum economic unit)
No. of Plants: -400-600 plants, depending on spacing.

Requirements:

(i) Polythene (Gauge 1000 Ultra Violet (U.V) treated).

Walls (sides) - 4m x 48m
Wider roof - 6m x 16m
Narrow roof - 5 m. x 16m.
gables - 6 m x 9m
Door shade - 4m X7m

(ii) Posts:

Side posts - 12 posts of 4m long
Mid posts - 6 posts of 5.5m

(iii) Rafters/timber

Trusses - 22 poles of 6m
Purlines - 9m x 6m
Wall plate - 30 x 6m
Wire supporters 6 x 6m
Side supporters 14 x 6m
Door shade posts 5 x 2.8m
Polythene fasteners 60 x 3m

(iv) Other requirements

Nails 30kgs
Smooth/barbed Wire- 1 roll
Hoop iron-10 kgs
black polythene sheet -65mx2m wide
Net 75 m x1m wide
Drip irrigation kit -1 drum kit
Crates-2
Nursery boxes/trays - (90×45x10) -2

Inputs

(i) Labour - for construction, digging trenches, mixing planting medium, leveling and crop management
(ii) Seeds - 5gms (1000 seeds)
(iii) Fertilizers - 10kgs DAP, 10kgs CAN and 10kgs CN for top dressing. Foliar feed - 2 litres or 2kgs
(iv) Insecticides and fungicides
- Insecticides - systemic (1 litre) and
- Contact (1 litre) at harvesting
Fungicides - Preventive (1kg) and
- Curative (1kg).
- Alternate preventive fungicides with curative fungicides for effective disease control and to avoid disease resistance.

Crop Management in the Greenhouse:

Nursery Establishment

a) Green house varieties:-
Anna, Arleta, Nemoneta, Monset, Monyala, Ken Tom etc
b) Construction of germination boxes

Measure boxes of 100cm (length) x 45cm (width) x 10cm (depth)
Fill the first 5cm of the box with small stones (2 inches) followed by 2cm of sand and then 2cm of forest soil mixed with well rotten manure or use the already mixed growing medium
Mix the forest soil/growing medium with a handful of DAP fertilizer and Nematicide to control nematodes.
Make drills of 8cm apart, leaving 5cm from both edges of the box. This gives 10 lines/box
Plant 50 seeds per line (to give 500 seeds/box). 2 boxes are required per green house unit.

c) Nursery Management

After sowing, cover the seeds with a thin layer of soil or sisal bag and water immediately

Water twice a day, early in the morning and late in the evening for the first 2 weeks Reduce watering in the third week to harden off the seedlings

Transplanting

Transplanted at 3 weeks.
Water the beds. Transplant late in the evening or early in the morning on a cloudy day
Dig holes at 50cm x 30cm in zigzag or alternate (in tandem)=400 plants or 33cm x 30cm= 600 plants per green house
Apply 20gms per hole (1 tablespoonful) of DAP/TSP/DSP and mix thoroughly with the planting medium to avoid direct contact with the seedlings. The fertilizer may be applied three days after transplanting. Water thoroughly after fertilizer application.

Note: When transplanting spray with Preventive fungicide such as Dithane M45, Milthane Super, Sancozeb, etc.
After transplanting, initial watering should be mixed with a curative fungicide to eradicate any fungal manifestation e.g. Ridomil, Equation Pro, Galben, Milraz, Acrobat etc.

Training/trellising

A strong wire 10-14 gauge is placed parallel to the row of plants from one end of the house to the other at the height of the posts (3 m) from the ground.
Sisal twine is tied around the stem base of the plant, which is then trained to achieve 8 - 12 trusses of tomatoes.

Dibudding/De-Suckering:

Done early to remove side suckers or branches to leave one stem only per plant.

Bud Nipping:-

To get healthy and uniform fruits remove apex or growing bud when plant achieves 8-12 trusses (to remove apical dominance)

Leaf Trimming and Defoliation

This is cutting of leaves and removal of excess leaves in order to avoid bushy plants, which reduce fruit growth.

Top Dressing:

Apply 20g of CAN per plant, 2 weeks after transplanting and 20g CN (Calcium Nitrate) 2 weeks later to encourage vigorous growth.
Thereafter apply foliar feed at 2 weeks interval to provide micronutrients.