/ Brassica Kholrabi / Cruciferaceae / German turnip/turnip cabbage is a variety of cabbage and is an annual vegetable crop. It can be eaten raw or cooked. In India, it is called Noolkol, Seema mullangi, Gaanth gobhi, Navalkole, Navil Kosu, Olkopi and so on.
Commercial cultivation of Kohlrabi is limited and is mostly grown in J&K, Assam, WB, Maharashtra, UP, Punjab and some parts of south India. It is mostly used as a vegetable. It is excellent if it used at an early stage. There are two varieties of Kohlrabi, namely the early and the late variety. Some popular varieties grown in India are Sutton’s Earliest Purple (Sutton), Golith White (Sadashiv), Early White Vienna, King of North, Large Green and Early Purple Vienna (Verma, Pocha).
Kohlrabi is a cool season crop and grows well in relatively cool moist climate. This is one vegetable crop, unlike most others that can easily tolerate frost conditions. Knolkol is good for the circulatory system, it helps fight cancer, promotes healthy digestion and boosts immunity among many other benefits. It is not as popular as the other vegetable crops but all the same, it used as food by many Indians.
The edible portion of the vegetable is globular. Knolkol is characterized by the formation of tuber or the knob which arises from the thickening of the stem tissue. The fleshy turnip-like enlargement of the stem develops entirely above the ground. This knob is harvested for human consumption mainly as mentioned above. It is eaten raw or cooked as a vegetable, though in some parts, young leaves and stem are also used. Knolkol can be grown in all types of soil.
King of North has a plant height of 20 – 30 cm foliage and is dark green, leaf sheath large and well-spread over the knob. It matures 60 – 65 days after transplanting. The Large Green variety has green, round, large-sized knobs with small tops. The knobs are tender, delicately flavored with white flesh. It is ready for harvesting in 76 days with an average yield potential of 225 – 250q/ha. It has been recommended for mid and high hills of the western Himalayas.
Purple Vienna has knobs that are purplish-blue with greenish-white flesh. It has purple leaves. It requires 55 – 65 days for knob formation with slightly better yield potential than White Vienna. White Vienna is an early variety with globular, light green, smooth, tender, medium-sized knobs having creamy-white tender flesh with a delicate flavor. Its plants are dwarf, leaves and stems are medium green. It has a yield potential of 150 –200q/ha. It matures 55 – 65 days after transplanting. Early White Vienna has dwarf plants, short tops and globular round knobs. It takes 50–60 days for knob formation.
As mentioned earlier, knoll khol is used as a vegetable in India. Some of the dishes made from Knol khol are Knol Khol Khalan curry, Kohlrabi chana dal sabzi, Noolkol Kootu, Kohlrabi Kurma, Noolkol masala, Monji Haakh, etc.
Image source – spiceflair.com
Image source – slideshare.net
As you can see above, they are available in colors such as purple, white and light green. The roundness also differs slightly. Some are round and some are oval in shape. But it is generally a stout, round, tuberous vegetable. It is closely related to cabbage, broccoli, cauliflower, kale, collard greens and Brussel sprouts and hence it is no wonder that its taste may remind you of one the related varieties mentioned here.
It basically looks and feels like a turnip and can be used raw in salads as well. It may be slightly sweeter than its close relatives, especially when it is cooked. It is usually cooked as gravy with a lot of flavoring and spices. It is rich in vitamins and has excellent dietary fiber and hence a favorite among weight watchers. The leaves are also considered very nutritious and are rich in carotenes, vitamin-A and vitamin-K.
Process of growing Kohlrabi
⦁ Time / Season / Climatic Conditions –
Kohlrabi is a cool season crop and thrives in cool, moist climate. It can withstand frost conditions without any problem. It grows well in temperatures of 15 – 30 °C.
In the plains of North India, planting is done in September
In the winter regions, planting is done in October
In the hills of North India, seeds are sown from March-August
⦁ Seed Rate / Spacing –
Knolkol is normally propagated by seeds or cuttings such as tip cutting and leaf cutting. The seeds are sown in lots from the end of August to the end of November for a continuous crop. Seeds are sown @ 1 – 1.5 kg/ha.
Seeds are given hot water treatment for half an hour to protect against black rot and Apron 35 @ 2g/kg seed against downy mildew. The seedlings are raised in nursery beds. 3 – 4-week old seedlings are transplanted using the ridges and furrow type of layout. The seedling is transplanted at a distance of about 30 cm row – row spacing and 20 cm. Plant – plant spacing. Closer spacing of this vegetable increases the yield. After transplanting, the seedlings should be watered and protection may be given from sun rays for 4 – 5 days.
Depending on the variety of seeds, sowing is done as follows –
The early variety – August – September
The main variety – September – October
The late variety – October – November
⦁ Soil type / Land preparation / Irrigation –
Sandy loam soils are best suited for Kohlrabi cultivation for an early variety. Clay or silt loam soils are used for higher yield and late variety crops. The soil must be tested before sowing seeds. A pH of 5.5 – 7.0 is considered best for sowing seeds.
Plough the field 3 – 4 times to get fine tilth stage. After plowing, planking is done to level the soil. Any harmful weeds present must be removed at this stage. Prepare beds and channels for irrigation. Transplanting is done on a cloudy day or in the evenings. Press the soil and give light irrigation. Add 20 – 25 tons of well-decomposed FYM and 70, 75 kg N, P and 50 kg P/ha. The second dose of 50 kg N is given a month later. Aldrin or Heftaf or Heptachlor 5 % or BEC 10 % should be applied @ 10 – 15 kg % with the last preparatory tillage to check the infestation of termites and cutworm. Hoeing and weeding are done after each irrigation and the plant should be earthen up after 25 – 30 days of transplantation.
On light and drought-sensitive soils, sunken nursery beds are preferred. Acidic soils should be limed. For minimizing the seedling damage, the nursery beds should be treated with formalin (40% formaldehyde diluted in 5–6 parts of water). The soil is saturated with this solution, requiring 5 liters/m2. Fumes are then confined by covering nursery beds with polythene for 2 days and then the soil is aerated well for at least 4 days before sowing. This treatment can be replaced by the use of Captan (0.3%) for soil drenching.
The nursery bed is covered with grass to conserve moisture for uniform germination. It is watered as and when required with a watering can. The mulch is removed just before the seed germination to control damping off, drenching with Dithane M-45 (0.2%) is recommended.
Kohlrabi requires adequate moisture for uniform growth and development of knobs. After transplanting, the seedlings should be watered for 4 – 5 days. Irrigation should be given an interval of 7 – 8 days. But the field may be irrigated when the soil is deficient in moisture. Heavy irrigation should be avoided in KnolKol cultivation. Irrigation should be done as when required or when the soil moisture goes below 50% of the field capacity. It is not an easy crop to grow as the others and requires a lot of care at each stage.
Regular intercultural operations are done to keep the plantation weed free. Different climatic conditions may yield different shaped Kohlrabi, for example, normally they are round and tuberous, but in hot weathers, they can become elongated too. Maintaining the farm after planting is very important in Kohlrabi cultivation. Please contact your local horticulturist for information regarding treatment of soil and usage of various fertilizers to keep a steady crop growth.
Ensure you perform timely hoeing and removing any visible weeds. This is very important and regular checks are required to discourage and remove weeds. Neglecting the crop can lead to well-developed weeds which will hamper the roots of the crop on removal. So do not allow them to grow at all. Once the soil is covered with foliage, hoeing operations can be stopped.
⦁ Weed Management / Pest control –
Intercultural operations help control weeds. Regular hoeing and weeding need to be done after irrigation. Manual removal of weeds can also be done if needed. As soon as weeds start appearing, ensure you perform shallow hoeing until the soil is covered in foliage. Manual removal should be avoided during the knob development stage. Black polythene mulch can also be used to control weeds.
Monocot and Dicot weeds can be controlled by spraying Treflan @ 0.5 liters/ha and Semeron @ 1kg/ha
Use of Stomp @ 1 – 2 kg/ha is found to be very effective in ridding weeds
Weedicide applications are supplemented with a couple of hoeing for better success and also prove to be more economical
Other existing weeds are Clubroot, Downy mildew, powdery mildew, leaf spot, black rot, cutworms, flea beetles, cabbage looper, Thrips, aphids, etc.
For more information on treating weeds, pests, and diseases in Kohlrabi, please contact your local horticulturist.
⦁ Harvesting –
The knobs are harvested by cutting the stem just below with a knife or sickle, whatever is available. For the market, the plant is harvested at the root portion. The yield of Kohlrabi depends on many factors such as variety, soil type, climate and so on. Usually, you can expect a yield of 300 quintals/ha.
The knobs of early varieties may have an average weight of 200 – 250g while the late ones weigh up to 1kg. Generally, the yield may vary from 12 – 30 tons/ha.
Kohlrabi is available from November – March. Once it chopped, it gets tough and woody. Also in the summers, it tends to get tough and not very enjoyable to eat. Hence ensure you pick the soft and tender ones while buying from the market. They are the ones that are a sweet and easy cook. Buy medium sized ones that are available in the market. Avoid the ones with cracks and cuts, lightweight, and the tough, woody ones.
Kohlrabi can be stored at room temperature for up to 5 days. If you wish to store is for a few more days, you can refrigerate it. But it could lose its sweetness and tenderness and may become harder to cook and not that great to taste. Ensure you wash well before use, as it is usually sprayed with a lot of fungicides and Weedicides.
⦁ Benefits of Kohlrabi –
⦁ KnolKol is mildly sweet, crispy textured and rich in vitamins and dietary fiber.
⦁ It contains 27 cal/100 g, a negligible amount of fat, and zero cholesterol and hence it is good for weight watchers
⦁ Fresh kohlrabi stem is a rich source of vitamin-C and provides 62 mg/100 g. Vitamin-C (ascorbic acid) is a water-soluble vitamin, and powerful antioxidant and helps maintain healthy connective tissue, teeth, and gum.
⦁ Its antioxidant property helps combat diseases and cancers by scavenging harmful free radicals from the body.
⦁ Kohlrabi contains health-promoting phytochemicals that protect against prostate and colon cancers.
⦁ It contains good amounts of many B-complex groups of vitamins such as niacin, vitamin B-6 (pyridoxine), thiamin, pantothenic acid, etc., that acts as co-factors to enzymes during various metabolic functions
⦁ Potassium is an important component of cell and body fluids that helps controlling heart rate and blood pressure by countering effects of sodium.
⦁ Kohlrabi leaves or tops, like turnip greens, are also very nutritious greens abundant in carotenes, vitamin-A, vitamin-K, minerals, and the B-complex group of vitamins.
Principle Nutrient Value
Energy 27 Kcal
Carbohydrates 6.20 g
Protein 1.70 g
Total Fat 0.10 g
Dietary Fiber 3.6 g
Folates 16 µg
Pantothenic acid 0.165 mg
Pyridoxine 0.150 mg
Riboflavin 0.020 mg
Thiamin 0.050 mg
Vitamin A 36 IU
Vitamin C 62 mg
Vitamin K 0.1 µg
Sodium 20 mg
Potassium 350 mg
Calcium 24 mg
Iron 0.40 mg
Carotene-ß 22 µg