Seed production basics for African indigenous vegetables
This informational brochure about African indigenous vegetable seed production was created by David Byrnes and Jim Simon of Rutgers, the State University of New Jersey for the Horticulture Innovation Lab project. "Improving Nutrition with African indigenous vegetables in Kenya and Zambia."
Introduction
Seed production is highly specialized. Seed production of certain crops may be easier than others depending on maturity period, mode of reproduction, susceptibility to seed-borne diseases and seed multiplication factor.
Amaranth (Amaranthus spp.) - Mchicha
Important species of amaranth are A. cruentus, A. caudatus, A. hypochondriacus. tricolor and A. dubius
Land selection
Amaranth is a predominantly self-pollinated crop. The isolation required to separate one variety from the other is 100 meters. The land selected should not have hosted any amaranth crops in the previous season so that contamination from previous crops can be prevented and the build up of soil-borne diseases, reduced.
Land preparation
Amaranth seeds are very small and therefore the soil should be very well prepared without clods or crusts.
Planting
Spacing is 25 cm within rows and 50 cm between rows. Seed rate is 1.5-2 kg kg/ha. You can conduct germination tests to determine the actual seed rate. Amaranth can be established by transplanting seedlings or sowing directly by drilling in rows and thinning after about three weeks.
Weed control
The seed plots should be kept free from weeds for high quality seed. Amaranth has wild types (A. viridis and A. spinosus) and seeds of the variety under production should not be allowed to mix with the wild type.
Fertilizer application
Incorporating 20-30 t/ha of manure into the soil during ploughing is recommended. Chemical fertilizer compound (10-20-20) may also be applied at planting and 40% N as topdressing.
Crop protection
To manage diseases, start with disease-free seeds and fields. Diseases can be transmitted by wind, insects or plant debris. Disease can be controlled by roguing and timely use of pesticides. Amaranth seed transmitted diseases like stem rot and leaf lot can be controlled by using healthy seeds.
Pests
Leaf eating caterpillars, beetles, nematodes
Roguing
Roguing ensures that the seed lot produced is of the highest genetic, sanitary and physiological quality possible. Roguing is done by regularly inspecting the seed field and removing any off-types or diseased plants. The entire plant should be removed by pulling or cutting before it flowers. Characteristics to consider when roguing are general appearance, leaf color and shape, the color of flowers in the spike, the physical characteristics of the spike, plant height, disease prevalence and maturity period.
Harvesting
Different varieties mature at different times. When the seed is mature, panicles of individual plants should be cut down and then laid on tarpaulins, polythene sheets or woven large mats (mkeka) and dried. The seed is then threshed, winnowed and collected in containers for storage. When one waits too long to harvest, seeds might shatter on the ground -- reducing the yield.
Expected seed yield
This will depend on the variety of Amaranth. This can be from 200-300 kg/ha for species like tricolor and 1-1.5M T/ha for A.cruentus
Storage can be improved by:
- Harvesting under dry conditions
- Drying immediately after harvesting
- Storing at low relative humidity
- Storing well-dried seeds in airtight packaging
Spiderplant (Cleome gynandra)- Mwangani
Land selection
Spider plant is a cross-pollinated crop. The isolation required to separate one variety from the other is a minimum of 200 m for certified seed and 400 m for high status seed (Breeders’-basic). Crop rotation is necessary to avoid pest build up and minimize infestation.
Land preparation
Spider plant seeds are very small and therefore the soil should be very well prepared without clods or crusts.
Planting
Spacing is 25-30 cm within rows and 50 cm between rows. Seed rate is 6 kg/ha. Spider plant is often directly sown by drilling. For even distribution while sowing, mix seed with sand in the ratio of one to ten. Plant seeds in soils with sufficient moisture to ensure good emergence.
Weed control
The initial growth of spider plant is slow and therefore early weeding is necessary. This encourages vigorous growth.
Thinning
Thinning should be done 3-4 weeks after sowing.
Fertilizer application
Well decomposed manure of humid state is recommended at 3 kg per sq. m. Compound fertilizer 10-10-20 is applied at a rate of 2 tablespoons in one meter. Basal application is important.
Crop protection
To manage diseases start with disease-free seeds and fields. Diseases can be transmitted by wind, insects or plant debris. Disease can be controlled by roguing and timely use of pesticides.
Pests
Flee beetles, aphids, nematodes, and harlequin (hurricane) bugs (Bagrada hilaris), stem borer, pod borer and cutworms are common pests in spider plant. These are controlled by using recommended pesticides, practicing crop rotation and the application of ash in African villages.
Roguing
Roguing ensures that the seed lot produced is of the highest genetic, sanitary and physiological quality possible. Roguing is done by regularly inspecting the seed field and removing any off-types or diseased plants. The entire plant should be removed by pulling or cutting before it flowers.
The plants of spider plant varieties show much variation and the varieties tend to be unstable because of the ease of crossing during breeding. Characteristics to consider when roguing are: general appearance, stem color, leaf color and shape, the color of flowers in spike, plant height, pest and diseases prevalence and maturity period.
Harvesting
Harvesting is done when seeds are mature by cutting panicles or the entire stem. This should be timed well to avoid loses due to shattering. The pods should be laid on tarpaulins, polythene sheets or woven large mats (mkeka) to dry. The seed is then threshed, winnowed and then collected in containers for storage. Spider plant seeds undergo a period of dormancy after harvesting.
Expected seed yield
Estimated seed yield is 500-1000 kg/ha
Postharvest handling
Factors that result in reduced seed viability are:
- Delay of seed drying
- Poor seed drying
- Poor storage conditions
Storage can be improved by:
- Harvesting under dry conditions
- Drying immediately after harvesting
- Storing at low relative humidity
- Storing well-dried seeds in airtight packages
African nightshade (Solanum spp.)- Mnavu
Introduction
Types of African nightshade commonly grown in western Kenya include S. vilosum, S.americanum, S.eldoretii and S. scrabrum
Land selection
African nightshade is a self-pollinated crop. The isolation required to separate one variety from the other is a minimum of 25 m for certified seed and 50 m for high status seed (Breeders’-basic). Crop rotation is necessary to avoid pest build up and minimize infestation.
Land preparation
African nightshade seeds are very small and therefore the soil should be very well prepared without clods or crusts.
Planting
African nightshade seeds may be sown directly or started in the nursery. Spacing is 30-40 cm within rows and 50 cm between rows. Seed rate is 6 kg/ha. Transplant when leaves are 10-15 cm tall. Thinning should be done four weeks after sowing in the case of direct planting.
Fertilizer Application
Combine farmyard manure and inorganic fertilizer for best results. Well decomposed cattle manure is applied at a rate of 2-6 kg per sq. m depending on soil type and quality of manure. Calcium ammonium nitrate can be applied at a rate of three teaspoons in one meter or row.
Crop protection
To manage diseases, start with disease-free seeds and fields. Diseases can be transmitted by wind, insects or plant debris. Disease can be controlled by roguing and timely use of pesticides. Birds are common pests in African nightshade at seedling and fruiting stages. Other major pests are flee beetles, aphids, and nematodes. The best way to avoid diseases like early blight, Anthracnose, wilt, canker and mosaic virus is to rogue crops that show symptoms and to only harvest plants if they do not show symptoms.
Roguing
Roguing ensures that the seed lot produced is of the highest genetic, sanitary and physiological quality possible. Roguing is done by regularly inspecting the seed field and removing any off-types or diseased plants. The entire plant should be removed by pulling or cutting before it flowers. Characteristics to consider when roguing are: the general appearance, leaf shape, stem color, the color of flowers, plant height and maturity period.
Harvesting and Processing
S.Villosum can be picked when berries turn yellow and S.eldoretii fruits fall down easily when fruits become ripe. Fruits of S. scrabrum remain on the plant when ready.
There are two methods of processing African Nightshade seed:
1. Collected fruits are squeezed in water, washed thoroughly and dried preferably in shade till properly dry.
2. Fruits are put in a polythene bag and kept there for three days to allow them to ripen and ferment. Next, they are removed, dried properly and rubbed to separate seed from chaff. Seeds are then stored in clean, sealed containers.
Postharvest handling
Factors that result in reduced seed viability are:
- Delay of seed drying
- Poor seed drying
- Poor storage conditions
Storage can be improved by:
- Harvesting under dry conditions.
- Drying immediately after harvesting
- Storing at low relative humidity
- Storing well-dried seeds in airtight packages
