Origin and Common Names
Brassica campestris L. var. rapa (L.) Hartman, also known as turnip, belongs to the Cruciferae family. It is believed to have originated from Eurasia and has been cultivated for thousands of years. This plant is referred to as many names, including turnip-rooted cabbage, white turnip, and Chinese turnip. In some regions, it is also called neep or swede.
General Appearance
Turnips are biennial plants that grow 10 to 60 centimeters high. They have a taproot that can reach up to 25 centimeters in diameter. The leaves are lobed and can be smooth or hairy, measuring 5 to 20 centimeters long. In the first year of growth, the turnip produces leaves and stores nutrients in its swollen root. During the second year of growth, the plant produces a flowering stem that can reach up to 1 meter high and has yellow flowers.
Uses
Turnip roots are commonly eaten as a vegetable and can be cooked in various ways, including roasted, boiled, or mashed. The greens can also be cooked and eaten as a side dish or used in soups and stews. In traditional Chinese medicine, turnip seeds are used to treat respiratory problems, while the root is used to improve digestion and reduce inflammation. Turnip oil is also used to make soap and lubricate machinery.
Aside from its culinary and medicinal uses, turnips can also serve as a forage crop for grazing animals. Additionally, the plant can be used as a cover crop to prevent soil erosion and improve soil health by adding organic matter.
Light Requirements
Brassica campestris L. var. rapa (L.) Hartman, commonly known as turnip, has moderate shade tolerance, but it prefers to grow in full sun. Therefore, it requires at least six hours of direct sun exposure every day for optimal growth and development. Lack of sunlight can lead to weak stems, small and pale leaves, and delayed flowering.
Temperature Requirements
The ideal temperature range for the growth of Brassica campestris L. var. rapa (L.) Hartman is between 18°C and 24°C. This crop has moderate tolerance to frost, but it shows poor growth at temperatures above 30°C. High temperatures can cause wilting, premature flowering, and reduced fruit yield, while cold weather can result in stunted growth, delayed flowering, and poor root development.
Soil Requirements
Turnips prefer well-drained loamy soils with a pH range between 5.5 to 7.0. The soil should be rich in organic matter and free from heavy metals and salt content. The crop also prefers soil with high fertility levels and proper aeration. Compacted soils can lead to poor root development and limit the water and nutrient uptake by the plant. Moist and cool conditions are necessary for the proper establishment of the crop.
Cultivation
Brassica campestris L. var. rapa (L.) Hartman, also known as turnip, thrives in well-drained and fertile soil. The ideal soil pH for turnip cultivation ranges from 5.5 to 7.5. It is essential to prepare the soil adequately before planting by removing weeds, rocks and till the soil to a depth of at least 20 cm.
The optimal temperature range for turnip growth is between 13°C to 24°C, with a minimum of 7°C for germination. Planting turnip seeds in early spring or late summer will provide the best growing conditions for the plant.
Watering Needs
Turnip requires regular watering for healthy growth and good root development. It is essential to ensure consistent moisture levels in the soil, especially during the early stages after planting. Inadequate watering causes the roots to be woody and less flavorful. However, excessive watering results in poor root development and increased risk of diseases.
It is recommended to water the plants once a week, especially during hot and dry seasons. A sufficient amount of water for turnips to have a healthy growth is at least 1 inch of water every week.
Fertilization
Fertilization is necessary for the turnip plant to grow healthy and produce abundant yields. Before planting, it is recommended to add well-rotted manure or compost to the soil. Adding nitrogen-rich fertilizers also helps to improve the quality of the plants.
The frequency of fertilizer application depends on the soil nutrient levels and the growth stage of the plant. Applying fertilizer during the early stages of growth helps to promote healthy leaf development, while the application of phosphorous-rich fertilizer at a later stage boosts the root growth.
Pruning
Pruning turnip plants mainly involves thinning the seedlings, removing unwanted growth, and deadheading flowers.
Thinning the plants entails removing the extra seedlings to allow better spacing and air circulation. This process helps the plants grow lucidly and reduces the competition for nutrients and moisture in the soil.
Removing the unwanted growth involves cutting back the leaves and stems that are overcrowded or damaged. This helps prevent issues like mold, mildew, and other diseases.
Deadheading flowers is done to channel the plant's energy towards developing the roots and leaves. Turnips produce small yellow flowers that need pruning to ensure the plant focuses on healthy root development.
Propagation methods of Brassica campestris L. var. rapa (L.) Hartman
Brassica campestris L. var. rapa (L.) Hartman, also known as turnip, is a biennial plant that belongs to the Brassicaceae family. This plant is propagated both sexually and asexually.
Sexual propagation
The sexual propagation method involves the use of seeds. Turnip produces a large number of small seeds that can be sown directly into the soil or raised in seed beds. The best time to sow the seeds is in early spring or late summer. Before planting, the soil must be properly prepared by clearing the weeds and adding organic matter to improve its fertility and structure.
The seeds should be sown at a depth of 1-2 cm and spaced at an interval of 15-20 cm between rows. The seedlings will germinate within 5-10 days and can be thinned to maintain a distance of 10-15 cm between plants. Turnips grown from seeds take about 6-8 weeks to mature.
Asexual propagation
Asexual propagation of turnips involves the use of stem cuttings and root cuttings.
The stem cuttings are obtained by cutting a healthy stem from a mature turnip plant and planting it in a rooting medium under controlled conditions. The rooting medium could be a soilless mix of peat and perlite, or a mixture of sand and vermiculite. The cuttings should be planted deep enough to cover at least two nodes and placed in a shaded area to prevent excessive water loss.
Root cuttings, on the other hand, are obtained by cutting the roots of a mature turnip plant into small sections of about 5 cm long. The sections are then planted horizontally in a trench or a furrow, covered with soil, and watered well. The cuttings will develop new roots and shoots within a few weeks and can be transplanted after 6-8 weeks.
Overall, the choice of propagation method for Brassica campestris L. var. rapa (L.) Hartman depends on the purpose of the plantation and the availability of resources. Sexual propagation is more commonly used for large-scale farming, while asexual propagation is employed in small-scale gardening or for the propagation of specific varieties.
Disease Management for Brassica campestris L. var. rapa (L.) Hartman
Brassica campestris L. var. rapa (L.) Hartman is susceptible to various diseases that can result in significant yield loss and quality reduction. Effective management of these diseases is critical to ensure a profitable crop.
The most common diseases that affect Brassica campestris L. var. rapa (L.) Hartman are:
- Clubroot: This is a serious soil-borne disease that results in the deformation of the roots and stunting of the plant's growth. It can be managed by proper sanitation and crop rotation.
- Black rot: This bacterial disease affects the leaves and stems of the plant, causing V-shaped lesions. The best way to manage black rot is to plant disease-resistant cultivars and to practice good sanitation practices.
- Downy mildew: This fungal disease is characterized by yellow patches on the leaves, which then turn brown and die. Crop rotation and the use of fungicides can help manage downy mildew.
Pest Management for Brassica campestris L. var. rapa (L.) Hartman
In addition to diseases, Brassica campestris L. var. rapa (L.) Hartman is also susceptible to pests that can damage the crop. Some of the most common pests that affect this plant include:
- Aphids: These small insects feed on the plant's sap, causing the leaves to wilt and yellow. Aphids can be managed using insecticides or by introducing natural predators such as ladybugs or lacewings.
- Cabbage loopers: These are caterpillars that feed on the leaves of the plant, resulting in defoliation. They can be managed using insecticides or by introducing natural predators such as birds or parasitic wasps.
- Diamondback moths: These moths lay their eggs on the leaves of the plant, and the resulting larvae feed on the foliage. Diamondback moths can be managed using insecticides or by introducing natural predators such as parasitic wasps.
Integrated pest management (IPM) practices can be used to manage both diseases and pests in Brassica campestris L. var. rapa (L.) Hartman. This approach involves a combination of tactics, including cultural practices, biological control, and judicious use of pesticides, to minimize the impact of diseases and pests on the crop.
