INTRODUCTION
A hybrid of orange, Tangerine (Citrus reticulata), is a sweet citrus fruit in the same family as orange, grape, lemon, and lime (Family Rutaceae). It is a small thin-skinned variety of orange belonging to the mandarin orange species of the family Rutaceae.
It is probably indigenous to southern Asia. It has a tender, juicy and orange-colored pulp. It is commonly called mandarin, tangerine, temple orange, etc. Tangerines are smaller and less rounded than common oranges. The taste is considered less sour, as well as sweeter and stronger, than that of an orange.
Tangerine is a widely cultivated fruit tree in many warm temperate to tropical areas. It is small and evergreen and grows about 8m tall. It has an axillary thorns. The leaves are dark green, long, and narrow. This fruit has been cross-breed with the grapefruit (Citrus paradisi) to form the tangelos (Citrus tangelo).
Mandarins or tangerines are the second most important citrus type grown through the world with 17% of total production in 1998–99, after oranges (with 66%) but ahead of lemons and limes (11%), and grapefruit (6%). When in season, this fruit is readily available for purchase in markets, stores, and roadside sellers.
(Image source: www.mashed.com)
Importance
Tangerines are most commonly peeled and eaten out of hand. The fruit is known for its fresh and citrus taste with its low calorie and high nutrient content. The vitamin content in the fruit is the best in its class. Tangerines are also a rich source of vitamin C, foliate, and beta-carotene.
Rich in Vitamin C, it is the perfect antioxidant required by the body. These antioxidants prevent inflammation in the body. They are known to prevent the formation of free radicals that make unnecessary oxidation reactions possible which may not be beneficial for the body. Tangerine fruit has been used quite frequently in medical treatments as they fight effectively against skin diseases and arthritis. They help in healing minor cuts and wounds.
They also help to absorb iron from food very easily. Tangerine consists of fibers like pectin and hemicellulose that restrict the absorption of cholesterol in the gut which cuts the risk of obesity. The dietary fiber in this fruit also improves digestion that is good for the overall working of the body.
Tangerine is a very important source of folate for pregnant women. Folates are needed for amino acid metabolism, the formation of red and white blood cells, cell growth, and cell division in the fetus. It also contains potassium which plays a great role in the maintenance of blood pressure.
Tangerine essential oil is an effective depurative. The oil helps purge your body of excess uric acid, extra salt, pollutants, and water through the excretory system. This oil is a characteristic ingredient in several flavors and liqueur.
Nutritional value of 100g of tangerine
| Energy | 223 kJ (53 kcal) |
| Carbohydrates | 13.34 g |
| Sugars | 10.58 g |
| Dietary fiber | 1.8 g |
| Fat | 0.31 g |
| Protein | 0.81 g |
|
4% 34 μg 1% 155 μg |
|
| Thiamine (B1) | 5% 0.058 mg |
| Riboflavin (B2) | 3% 0.036 mg |
| Niacin (B3) | 3% 0.376 mg |
| Pantothenic acid (B5) | 4% 0.216 mg |
| Vitamin B6 | 6% 0.078 mg |
| Folate (B9) | 4% 16 μg |
| Choline | 2% 10.2 mg |
| Vitamin C | 32% 26.7 mg |
| Vitamin E | 1% 0.2 mg |
Source: USDA nutrient database
Cultivation
Citrus reticulata requires a rainfall of between 1500mm and 2500mm. It grows better in deep well-drained loamy soils with soil pH between 5.5 and 6.5 and optimal temperature ranges between 25 – 30°C. The seed is best sown in containers as soon as it is ripe, after thoroughly rinsing it. Always sow stored seed in containers as soon as possible.
Germination usually takes place within 2 – 3 weeks at 13°C. Seedlings are liable to damp off so they must be watered with care and kept well ventilated. The seed is usually poly-embryonic, two or more seedlings arise from each seed and they are genetically identical to the parent but they do not usually carry any virus that might be present in the parent plant. When large enough to handle, prick the seedlings out into individual pots and grow them on until they are 10cm or taller before planting out into their permanent positions.
Tangerine seedlings and budded plants are both suitable for field planting. Planting is done at a spacing of 6m by 6m. Planting should be done either between May and June or September and October. For optimal growth apply manure or fertilizer twice a year in June and October. Irrigate when there has been a dry spell because tangerines are very sensitive to waterlogged soil. The plants dislike root disturbance and so should be placed into their permanent positions when young. If growing them in pots, great care must be exercised when potting them into larger containers.
Cultivars
According to the National Horticultural Research Institute (NIHORT), there are 14 varieties of mandarin/tangerine. These are Dancy, Clementine, King, Algerine tangerine, Kinnow, Satsuma (Florida), Ortanique, Kara, King (Florida), Murcott (Florida), Tunis, Sun-shine, Ponkon, and Cleopatra (Florida). These varieties are all suitable for planting in Nigeria and the planting stock is available.
Diseases
• Alternaria Brown Spot: Alternaria brown spot infections cause brown spots surrounded by yellow borders to appear on leaves. Sunken dark brown to black spots, also surrounded by a yellow halo, may appear on fruit. The spots on infected fruit that remain on the tree become corky. Alternaria brown spot can cause serious leaf and fruit drop.
• Citrus Scab: Citrus scab (Elsinore Fawcett) causes corky growth to develop on the fruit and on leaves and shoots. Fruit lesions begin as pink to light brown pustules, and later resemble cracked warts, turning yellow-brown and then dark grey. The growths can become so numerous that the fruit is distorted. Control citrus scab with an application of fungicide when leaves are one-quarter expanded and again at petal fall. Apply a final application 3 weeks after petal fall.
• Greasy Spot: This is caused by the fungus Mycosphaerella citri, greasy spot spores germinate on the undersides of leaves. They then enter the leaf tissue, causing blisters to form on the undersides of the leaves. Yellow spots develop on the upper leaf surface, followed by brown blisters on the undersides that darken and become slightly raised with a greasy appearance. These greasy spots also appear on upper leaf surfaces as the infection progresses. Defoliation can occur before these symptoms fully develop.
To control greasy spot, apply copper fungicide plus oil when symptoms first appear, and repeat applications in 7 to 10-day intervals as needed, thoroughly covering the undersides of the leaves.
• Phytophthora Rot: Symptoms of phytophthora fungal infection begin showing as root rot, and peeling bark on crown roots and the trunk at the soil level. The reddish-brown resin may also be seen oozing from infection areas above ground, and girdling of the trunk often occurs. Phytophthora rot typically results in plant decline symptoms, such as yellow chlorosis of leaf veins, defoliation, fruit drop, branch or twig dieback, and even death.
Soil applications of fungicides containing mefenoxam can control infections if applied. Follow the first application with 1 to 2 more applications in 3-month intervals. Foliar applications of fungicides containing fosetyl-al can also help manage infections. (compare with pest and diseases of orange)
Brown rot in tangerine (Image source: wwwsciencesource.com)
Pests and control measures
| Pest | Control measures |
| Leaf miner | Spray Dichlorvos 76 WSC at the rate of 1 ml/lit or Dimethoate 30 EC 1 ml/lit |
| Fruit sucking moth | Destroy Tinospora weed host. Bait with fermented molasses combined with malathion 50 EC @ 1 ml/lit. Bag the fruits with polythene bags punctured at the bottom. Apply smoke and set up light traps or food lures (pieces of citrus fruits). |
| Shoot borer | Prune the withered shoots 4 cm below the dried portions and spray Monocrotophos 36 WSC @ 1 ml/lit |
| Stem borer | Prune the branches containing grubs. Plugging the fresh holes with cotton soaked in Monocrotophos solution mixed @ 5 ml/20 ml of water |
| Fruit fly |
Collect and destroy fallen fruits. Spray Malathion 50 EC @ 1 ml/lit with 1% crude sugar (10 g/lit). Make use of traps to capture the flies to reduce their infestation. Set up Methyl eugenol 0.1% solution mixed with Malathion 50 EC 0.05% between 6 a.m. and 8 a.m. Use polythene bags fish meal trap with 5 gm of wet fish meal + 1 ml. Dichlorvos in cotton. 50 traps are required/ha, fish meal + Dichlorvos soaked cotton are to be renewed once in 20 and 7 days respectively. |
Harvesting, handling, and storage
This budded plant starts bearing fruits from 3 – 5 years after planting, while in the case of seedlings, it takes about 5-7 years. The yield ranges between 15 – 20 t/ha/year. Harvesting tangerine is best done in the morning on a clear, sunny day using clear scissors with rounded ends without causing injury to the fruit.
After harvesting, initial sorting should be done on the field by discarding the overripe, damaged, and diseased fruits. The harvested fruits should be placed carefully in padded field crates or small picking bags to prevent bruising of the fruits. The harvested tangerine should be washed with warm water (40-45o C) containing hydrochloric acid (150ppm), fungicide of benomyl (5–ppm), and a small amount of detergent for 3-4 mins.
Grading is done according to fruit size, weight, color, and maturity. Grading and sorting should be done to meet the objective of production. In most cases, tangerine is often harvested at maturity but for some cultivars of tangerine, the skin will still be green even at maturity. For some consumers, the green skin is assumed to mean immaturity of the fruit. In order to meet such consumer’s preferences, degreening can be done.
Degreening can be done by flowing ethylene into the storage chamber or by treating the fruits with 0.4% w/w of calcium carbide for 72hrs. Another post-harvesting operation that can be done to prevent loss of moisture and shriveling and extend the shelf life of the fruits is waxing. Waxing is done by applying an emulsion of bee wax, triethanolamine, oleic acid, and water. This should be applied by manual rubbing. (Read post-harvest handling of orange)
Tangerine fruits may be packed using corrugated cardboard filled by paddy straw in between layers. Or in wooden boxes. Matured tangerine fruits may be kept for 4-10 days at room temperature or 26 days at cool temperature. Storing at 5oC will extend the shelf life.
Uses and by products
Tangerine can be consumed raw, juiced or candied. For a protein boost, tangerine is used in fruit salad. It is also used in noodles and pastas. It is used in the confectionery and culinary industries as flavoring and additives.
Mandarins or tangerines are used as commercial processed products, mainly as segments in syrup or natural juice. The rind oil or essence, as often used in aromatherapy. After the juice has been extracted, there remain residues that can be a source material from which over 300 valuable by-products can be produced. Some specialized types are also candied (the peel), dried, or used for marmalade and pectin manufacture.
By products include but not limited to: Tangerine juice, Tangerine concentrates, tangerine pulp, Tangerine juice concentrates, Tangerine oil, and other essential oils.
Available market
Currently in Nigeria, tangerines are mainly sold to middlemen and retailers who sell in the open market. You can also sell to juice and beverage companies. You may also process into juice, concentrates, jams, marmalades and sell directly to consumers or sell to supermarkets. If quality can be controlled, tangerines can be exported.
Financial implication
Similar to every other agricultural venture, land is an important capital. Land acquisition is the first expense to be incurred. The cost of land vary based on location. Due to the perennial nature of tangerine, leasing a land for tangerine production may be very difficult.
Land clearing and preparation is another source of expenses. Acquisition of planting stock is another important expenses. Purchase of pesticides and other agro chemicals needed to nurture the tangerine to maturity is also important. All this has financial implication therefore before you venture into the orchard business ensure you have the needed capital to ensure the success of the venture.
Challenges of tangerine production in Nigeria
Just like every other fruit production in Nigeria, the major challenge is post-harvest wastage and this is as a result of improper handling and harvesting techniques and lack of value addition.
Opportunities in this sector
There is immense opportunity for investment in the tangerine value chain. From the orchard to consumption. Investing in a tangerine orchard will yield continuous profit because tangerines are perennial and produces fruits annually.
With proper handling and good storage facility you can be guaranteed of a steady source of income all through the year. Also, the area of value addition is a neglected aspect of the tangerine value chain in Nigeria and opportunities abound in that area.
Written by Ifedapo Rukayat O.
References
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