Amaranth is an herbaceous annual plant belonging to the family Amaranthaceae, with green or red leaves.
It has branched flower stalks bearing small seeds that are variable in colour from cream to gold and pink to shiny black. Locally it is known as terere or mchicha.
Amaranth can be used as a high-protein grain when the seeds are eaten as a cereal or as a leafy vegetable.
The seeds can also be ground into flour, popped like popcorn or cooked into porridge.
The leaves are cooked alone or combined with other local vegetables such as spider plant, cowpea, nightshade and pumpkin leaves.
The leaves are rich in calcium, iron and vitamins A, B and C, but are fairly low in carbohydrates.
Health benefits of amaranth include:
i) It improves digestion due to its high dietary fibre content.
ii) Juice from the leaves is used to treat diarrhoea and haemorrhage conditions.
iii) It is gluten-free and therefore suitable for people who are gluten intolerant.
iv) Vitamin A in the leaves improves vision.
v) Both leaves and grain have high quality protein.
vi) It reduces bad cholesterol and lowers heart diseases.
vii) Has antioxidants which fight harmful radicals hence prevent cancer.
viii) It lowers blood sugar levels and is thus good for diabetics.
ix) It prevents anaemia due to high levels of iron.
x) It prevents hair loss and premature greying.
Amaranth has a large number of species and varieties.
There are different varieties in different regions.
The choice of variety is influenced by the species available, leaf colour, taste and personal preferences.
Leaf colour varies from light green, dark green, red, purple and variegated.
Altitude: It needs 0 to 2,400m above sea level.
Temperature:Grows well within temperature range of 22-30°C. For seed germination, a minimum temperature of 15 to17°C is required.
It can be grown during both wet and dry seasons.
Irrigation is practised if crop is grown during the dry season.
Frequent application of water is required based on the stage of growth of the crop and the moisture retaining capacity of the soil.
Once the crop is established, it can withstand drought.
It does well in loam or silty-loam soils with good water-holding capacity, but it can grow on a wide range of soil types and moisture levels. Soil pH 4.5 to 8.
Propagation and planting
Thorough land preparation is needed and a well-prepared bed for good growth.
Prepare beds which are 20cm high during the dry season and 30cm during the wet season using a plough.
The distance between centres of adjacent furrows should be about 150cm with a 90cm bed top.
Planting is either by direct seeding or transplanting.
Seeds are either broadcasted or sown in rows.
Broadcast seeds uniformly at the rate of 0.5 to 1.0g/m2 of bed.
The seeds are very small and are therefore mixed with sand at a ratio of 1g seed to 100g sand.
This makes it easier to sow the seed and to obtain a uniform stand.
The seeds are then covered lightly with a layer of compost manure after broadcasting.
For row planting, furrows which are 0.5 to 1cm deep are dug and spacing between the rows is 10cm
It is done late in the afternoon or on a cloudy day to minimise shock.
Dig holes 10cm deep and place each transplant in its hole and cover the roots with soil and lightly firm.
Irrigate immediately after transplanting to ensure good root-to-soil contact.
Application of organic fertiliser benefits amaranth and increases yields.
The crop is drought-tolerant but insufficient water will reduce yield.
Apply water just after sowing or transplanting to ensure a good crop stand.
Over irrigation should be avoided as it enhances disease development and nutrient leaching.
Weeds compete for light, water, and nutrients leading to reduced yield.
Thorough land preparation is effective in weed control.
Weeding is essential in the early stages of growth.
The first harvest is done when the plants are 30cm, about six weeks after transplanting.
Plants harvesting can be done by uprooting the entire plant at once or by picking leaves and tender shoots several times at an interval of 2-3 weeks.
Eventually, the plants begin to flower and develop fewer leaves.
Frequent harvesting of leaves and shoots delays the onset of flowering and thus prolongs the harvest period.
Aphids are a major pest, causing leaves to curl as they feed by sucking plant sap.
Small aphid populations may be relatively harmless, but heavily infested plants usually have wrinkled leaves and stunted growth.
Plants, in particular young ones, may dry up and die under heavy aphid attack.
Heavy attack on older plants may cause crop loss by decreasing flower and seed production.
Damage may also reduce seed viability.
Use bio-pesticides (neem, ashes, soapy water).
Neem products such as Neemroc® (1-3%) and Neemros® water extract (50g/l) controlled the black bean aphid on vegetables.
They attack young seedlings.
The caterpillar emerges from the soil at night and cuts through the stem of young plants just above the ground level.
(i) Remove and destroy cutworms.
(ii) Proper land preparation to expose caterpillars to predators and to desiccation by the sun.
c) Leaf miners
These are small insects whose maggot makes long, slender, white mines (tunnels) in leaves.
Severely mined leaves may turn yellow and drop. If seedlings are mined they become stunted and eventually die.
(i) Handpick and destroy mined leaves.
(ii) Whenever necessary spray the crop with neem products.
(a) Damping-off diseases
Seeds may rot in the soil before emergence.
They can also exhibit stem canker above the soil line or root necrosis.
Affected seedlings eventually wilt (post emergence damping-off).
The disease is favoured by high soil water content and low soil temperatures.
Dense planting leads to insufficient aeration and this encourages development of the disease.
(i) Use disease-free seeds.
(ii) Avoid over-watering.
(iii) Avoid dense planting.
(b) Choanephora fruit rot
It is a fungal disease which causes wet rot of stems and leaves.
Affected plant parts have hairy appearance consisting of fungal spores.
It can cause heavy defoliation especially during the rainy season.
Air currents and infected seeds spread the disease.
Warm, moist conditions also favour development of the disease.
(i) Use resistant varieties where available.
(ii) Plant certified disease-free seeds.
(iii) Avoid dense planting to allow sufficient aeration
(iv) Field hygiene
(v) Spray copper based fungicides.
Ms Mutua is based at the Department Of Crops, Horticulture and Soils, Egerton University.