Overview
Guizotia abyssinica (L.f.) Cass. var. angustior (DC.) Oliv. & Hiern, also commonly known as Noug or Niger, is a plant species in the Asteraceae family. It is an herbaceous annual plant that is native to Ethiopia and other parts of Africa.
Description
The Guizotia abyssinica plant grows up to a height of 1-2 meters with a width of nearly half a meter. The plant has a single erect stem that grows from a taproot and has many branches with light green leaves. The leaves are lanceolate, nearly 6-10 cm long, and 1-1.5 cm broad. The seeds are small, black, and have a white or gray spot, measuring about 2-3 mm long and 1.5-2 mm wide. The plant produces small yellow flowers that bloom from August to October.
Common Names
Guizotia abyssinica is commonly known as Niger, Noug, Ramtil, Nyger, Blackseed, Inga Seed, and Oil Seed.
Uses
The seeds of Guizotia abyssinica are nutritionally rich, containing essential amino acids, protein, and oil that is rich in Omega-3 fatty acids. The plant seeds are used in food and feed industries for the production of cooking oil, biodiesel, and as birdseed. The oil extracted from Guizotia abyssinica seeds is also used in traditional medicine as a remedy for fever, rheumatism, and intestinal inflammation.
Light Requirements
Guizotia abyssinica (L.f.) Cass. var. angustior (DC.) Oliv. & Hiern requires full sun exposure for optimum growth and development. It thrives well in regions with at least six to eight hours of sunlight per day. Insufficient light may result in stunted growth, reduced yield, and a weakened plant.
Temperature Requirements
Guizotia abyssinica (L.f.) Cass. var. angustior (DC.) Oliv. & Hiern requires warm temperatures to germinate and grow. It tolerates temperatures between 20°C to 27°C but grows optimally in temperatures ranging from 25°C to 35°C. Frost and extremely cold temperatures can damage the plant, so it is best to grow it in areas with minimal to no frost occurrence.
Soil Requirements
Guizotia abyssinica (L.f.) Cass. var. angustior (DC.) Oliv. & Hiern grows well in well-draining loamy soils with a pH range of 6.0 to 7.5. The soil should be rich in essential nutrients such as nitrogen, phosphorus, and potassium, which are essential for proper growth and development. Adequate soil moisture is necessary, but waterlogging should be avoided as it may lead to root rot and other fungal infections.
Cultivation Methods
Guizotia abyssinica (L.f.) Cass. var. angustior (DC.) Oliv. & Hiern is an annual plant that is usually cultivated in tropical and subtropical regions. It thrives in sandy loam soils, and planting should be done at the onset of the rainy season, preferably in well-prepared fields of about 1m x 1m. The seeds should be planted at a depth of 1-2cm.
Watering Needs
The plant requires moderate watering, especially during the early stages of growth. A well-balanced watering schedule helps the plant to grow strong roots and establish well. After the first few weeks of planting, the frequency of watering can be reduced if the rainfall is adequate.
Fertilization
Applying fertilizers to the soil helps to enhance yield and maintain healthy growth. It is recommended to add manure or compost to the soil before planting. About 20-30kg of manure can be applied per hectare. Additionally, a balanced compound fertilizer (NPK) can be given at a rate of about 50-70kg/ha during planting. A top dressing of Nitrogen fertilizers can be given at the beginning of flowering, which enhances seed yields.
Pruning
Pruning helps to promote good air circulation and sunlight penetration, which enhances plant development. The plant should be pruned before the start of flowering to remove any diseased or unhealthy growth. The branches that cross or rub against each other should be cut back to reduce the chances of infection. Pruning can also be done after the harvest to remove any dead or damaged growth.
Propagation of Guizotia abyssinica var. angustior
Guizotia abyssinica var. angustior is commonly propagated using three main methods - seed propagation, stem cuttings, and layering.
Seed propagation
Seed propagation is the most commonly used propagation method for Guizotia abyssinica var. angustior. It involves sowing good quality seeds in a suitable potting mix. The seeds are usually sown during the onset of the rainy season. It is necessary to prepare the soil before sowing the seeds by tilling and removing any weeds or debris. The seedlings are thinned out, and the healthiest specimens left to grow to maturity.
Stem cuttings
Propagation of Guizotia abyssinica var. angustior can also be achieved through the use of stem cuttings. Stem cuttings of about 10 cm are taken from mature plants during the vegetative growth phase and planted in prepared soil. The cuttings should be taken when the plant is actively growing and free from pests and diseases. Rooting hormone can be used to stimulate root growth. The cuttings are watered regularly, and after a few weeks, they develop roots and start to grow.
Layering
Layering is another propagation method that can be used for Guizotia abyssinica var. angustior. This method is suitable for plants that are in their vegetative phase. It involves bending and burying a low growing branch or stem in the soil. The portion of the stem in contact with the soil will develop roots, and new plants will start growing from the stem. After the new plant is rooted and established, it can then be separated from the parent plant and potted in a new location.
Disease and Pest Management of Guizotia abyssinica (L.f.) Cass. var. angustior (DC.) Oliv. & Hiern
Guizotia abyssinica, also known as Niger or Nyjer, is a plant commonly grown for its oil-rich seeds used in bird feed. However, like other plants, Guizotia abyssinica is susceptible to several diseases and pests that can reduce its yield and quality. Below are common diseases and pests affecting Guizotia abyssinica and ways to manage them.
Diseases
1. Stem Rot: Stem rot is a common disease in Guizotia abyssinica, caused by the fungus Sclerotinia sclerotiorum. Stem rot causes wilting, yellowing, and eventual death of the plant. To manage stem rot, avoid planting in areas with a history of the disease, and maintain proper crop rotation. Chemical control is also possible using fungicides such as carbendazim and thiophanate-methyl.
2. Leaf Spot: Leaf spot is caused by the fungus Alternaria alternata and is characterized by the appearance of yellow-brown spots on the leaves. The spots may unite, causing the leaves to wilt and drop prematurely. To manage leaf spot, maintain good field sanitation and avoid overhead watering. Chemical control can be achieved through the use of copper-containing fungicides.
3. Root Rot: Root rot is caused by soil-borne fungi of the genera Fusarium and Pythium. Root rot results in root decay, wilting, and yellowing of the plant. To manage root rot, avoid overwatering and ensure proper drainage. The application of biological control agents such as Trichoderma spp. and Pseudomonas fluorescens can also help reduce the severity of the disease.
Pests
1. Aphids: Aphids are small, sap-sucking insects that cause curling and distortion of the leaves. Aphids also excrete honeydew, which encourages the growth of sooty mold. To manage aphids, practice good field sanitation and remove infested plants. Chemical control can be achieved using insecticides such as imidacloprid, acetamiprid, and thiamethoxam.
2. Whiteflies: Whiteflies are tiny, sap-sucking insects that cause stunting, yellowing, and curling of the leaves. Whiteflies also excrete honeydew, leading to sooty mold growth. To manage whiteflies, practice good field sanitation and avoid overfertilization. Chemical control using insecticides such as neonicotinoids, pyrethroids, and insect growth regulators is also effective.
3. Thrips: Thrips are tiny, slender insects that cause silvering and distortion of the leaves. Thrips feed on plant sap, leading to stunted growth and reduced yields. To manage thrips, practice good field sanitation and avoid overfertilization. Chemical control can be achieved using insecticides such as spinosad and abamectin.
In conclusion, diseases and pests can pose a significant threat to the yield and quality of Guizotia abyssinica. Therefore, early detection and proper management are essential to minimize losses. Integrated pest management techniques, including cultural, biological, and chemical control, can help reduce the severity of the diseases and pests affecting Guizotia abyssinica.
