Citrus sinensis (L. Osbeck) or oranges probably originated from South East Asia and were cultivated in China by 2500 BC, where it was referred to as ‘’Chinese’’ apple. Today, it is grown and consumed almost all over the world as a source of food for humans because of its high nutritional values. Citrus sinensis is a small evergreen tree 7.5 m high and in some cases up to 15 m. It is the most widely planted fruit tree in the world. According to FAO statistics in 2009, the global acreage for citrus was nine million hectares with production put at 122.3 million tonnes. Oranges are an all-season fruit that grows abundantly in late April and late May. Nigeria is one of the largest producers of citrus in Africa with about 14 states being major producers of this vitamin C-rich fruit.
Source: benuenews
Importance
It is an excellent source of vitamin C, a powerful natural antioxidant that builds the body’s immune system. Oranges contain important phytochemicals such as liminoid, synephrine, hesperidin flavonoid, polyphenols, pectin, and a sufficient amount of folacin, calcium, potassium, thiamine, niacin, and magnesium. It is also a major source of vitamins, especially vitamin C, a sufficient amount of folacin, calcium, potassium, thiamine, niacin, and magnesium.
It has recently been discovered that the biologically active, non-nutrient compounds found in oranges and other citrus fruits such as phytochemicals, soluble, and insoluble dietary fibers are known to be helpful in reducing the risks for cancers and other chronic diseases such as arthritis, obesity, and coronary heart diseases.
As an antioxidant: Oranges as an excellent source of vitamin C, contains natural antioxidants, folates, dietary fibers, carotenoids, and flavonoids that prevent cancer and degenerative diseases. Sweet orange also contains Naringenin which has a bioactive effect on human health as an antioxidant, free radical scavenger, anti-inflammatory, and immune system modulator. Thus, the consumption of oranges improves body immunity against infectious agents and scavenge harmful, pro-inflammatory free radicals from the blood.
Anti-inflammation: Citrus flavonoids contain compounds with anti-inflammatory activity due to the presence of regulatory enzymes (protein kinase C, phosphodiesterase, phospholipase, lipoxygenase, and cyclooxygenase) that control the formation of the biological mediators, responsible for the activation of endothelial cells and specialized cells involved in inflammation.
Anti-Cancer and anti-Arteriosclerosis: Citrus flavonoids can prevent cancer through selective cytotoxicity, anti-proliferative actions, and apoptosis. Flavonoids are anti-mutagenic, thus protects the DNA from damage by their ability to absorb ultraviolet light. They neutralize free radicals that promote mutations when they are generated near DNA. Oranges are also rich in iron, chlorine, manganese, zinc, sodium, phosphorous, iodine, calcium, folic acid, potassium, pectin, beta-carotene, and amino acids and fiber. A single orange is said to have about 170 phytonutrients and over 60 flavonoids with anti-tumor, anti-inflammatory, blood clot inhibiting, and antioxidant properties. All these properties help to promote overall health.
Anti-Obesity: Sweet oranges contain low calories and no saturated fats or cholesterol, but is rich in dietary fiber, pectin which is very effective in persons with obesity. Pectin as a bulk laxative protects the mucous membrane from exposure to toxic substances, as well as by binding to cancer-causing chemicals in the colon. Pectin has also been shown to reduce blood cholesterol levels by decreasing its re-absorption in the colon by binding to bile acids in the colon. Orange peels also contain synephrine, which reduces the production of cholesterol in the liver.
Nutrient composition of sweet oranges
| Nutrient composition of sweet orange | Composition Amount Energy 197 kJ (47 kcal) |
| Sugars | 9.35 g |
| Dietary fibre | 2.4 g |
| Fat | 0.12 g |
| Protein | 0.94 g |
| Water | 86.75 g |
| Vitamin A | equiv. 11 μg (1%) |
| Thiamine (vit. B1) | 0.087 mg (8%) |
| Riboflavin (vit. B2) | 0.04 mg (3%) |
| Niacin (vit. B3) | 0.282 mg (2%) |
| Pantothenic acid (B5) | 0.25 mg (5%) |
| Vitamin B6 | 0.06 mg (5%) |
| Folate (vit. B9) | 30 μg (8%) |
| Choline | 8.4 mg (2%) |
| Vitamin C | 53.2 mg (64%) |
| Vitamin E | 0.18 mg (1%) |
| Calcium | 40 mg (4%) |
| Iron | 0.1 mg (1%) |
| Magnesium | 10 mg (3%) |
| Manganese | 0.025 mg (1%) |
| Phosphorus | 14 mg (2%) |
| Potassium | 181 mg (4%) |
| Zinc | 0.07 mg (1%) |
Source: USDA Nutrient Database (2014)
Cultivation
Orange is a subtropical plant and the trees grow best in regions with a pronounced change in season. Trees will grow best when planted in a well-drained sandy loam with a pH between 6.0 and 7.5. The soil must be deep enough to permit adequate root development. Orange trees require full sun and should be protected from the wind which can cause damage to the trees. Orange seedlings are usually produced by grafting or budding to an appropriate rootstock as seeds will not produce fruit true to type. Orange trees can be purchased as seedlings that have already been grafted and only require planting in the garden or orchard. Standard sized trees should be spaced 3.7–7.6 m (12–25 ft) apart in an area that receives full sunlight but is protected from strong winds which can damage the trees. Newly planted trees require proper irrigation to ensure they become established. They should be watered 3-7 days interval. The young tree also requires a light application of fertilizer every month for the first year. It takes longer for an orange tree that was raised from seeds to mature and produce fruits (8-13years). However, vegetative propagation of seedlings takes between 2 and 3 years to produce fruits.
Cultivars or varieties of seed adapted to Nigeria
There are about 30 cultivars of sweet orange in Nigeria. They are Pineapple, Parson Brown, Washington navel, Carter Navel, Hamlin, Valencia late, Lue-gin-go, Agege 1, Etinan, Meran, Campbell- Valencia, Jaffa, Mid-sweet, Queen, Pope, Honiossa, Ruby-Blood, Pera, St Michael, Shamuti, Majorca, Sweet Seville, Boonis-Early-Or, Madam Vinous-Or, Ridge pineapple, Blood orange, and Natal. All these cultivars are adapted to Nigeria and the planting stock is available.
Pest and Diseases
- Pierce’s disease (PD): The disease is caused by Xylella fastidiosa, a xylem-limited bacterium, transmitted by sharp-shooter insects, contaminated bud wood, and natural root grafts. The insect vectors contact the bacterium through feeding on the xylem of infected plants and transmit the same to healthy plants. Disease symptom first begins as drying or “scorching” of leaves which become slightly yellowish (chlorotic) along the margins before drying out, or the outer leaf may dry suddenly while still green. The leaf dries progressively over a period of days to weeks, leaving a series of concentric zones of discolored and dead tissue. Other symptoms include premature leaf senescence, petiole ‘matchsticks’, incomplete periderm development, and eventually death.
- Citrus Variegated Chlorosis (CVC): This is also caused by Xylella fastidosa. The most prominent foliar symptoms of CVC are bright interveinal chlorosis and mottling resembling zinc deficiency, more pronounced on younger leaves, but may also be present on old leaves. In newly infected trees, the foliar symptoms are restricted to individual limbs, the underside of the leaf corresponding to the chlorotic area on the upper side becomes light to dark brown. Possible long-term management strategies in areas where the vector is present include: biological control of vectors, cultural methods, chemical control of vectors and pathogen, and eradication of infected citrus.
Source: etebu and Nwauzoma(2014)
- Citrus greening or Huanglongbing disease: Citrus greening also known as huanglongbing (HLB) disease is a very destructive disease of sweet orange. The disease has been associated with a phloem-limited fastidious, gram-negative bacterium of the Candidatus Liberibacter species. Symptoms include blotchy chlorosis and/or mottling of leaves, yellowish shoot, vein corking, stunted growth, poor root growth, small, greenish malformed fruits, and finally death. Other symptoms include twig dieback, poor flowering, and stunted growth. Fruits from diseased trees are small and distorted.
Rapid identification and culling of infected trees and bud woods in quarantine is the most important control measure. Early detection and removal of infected trees are presently encouraged to minimize damage and loss. And also the development of tolerant and resistant variety is a more effective alternative.
- Citrus Canker: Citrus canker is caused by Xanthomonas axonopodis. The disease starts as tiny blister-like lesions on the leaves and progresses to distinct necrotic-raised corky lesions that often have a yellow halo. The spots (technically called lesions) are usually surrounded by a yellow halo and can be observed on both the upper and lower sides of the leaf. The diseased stem and twig may appear scabby or corky, often surrounded by a water-soaked margin. The fruit shows dark brown to black lesions that are raised and often have a yellow halo.
Citrus canker in leaves. 
Citrus canker in fruit.
Source: Etebu and Nwauzoma (2014)
Harvesting and handling
The budded citrus plant may produce fruits within 3 years after transplant. The fruits stay on the tree for 6-9 months depending on the variety and climatic conditions. The fruits are ready for harvest when the color changes from green to yellow.
(To an earlier article on post harvest handling of oranges click here)
Storage
Fruits are better stored on the tree than in cold storage. Before placing into storage, fruit should be pre-cooled to slow respiration and treated with an approved fungicide to reduce decay. Oranges can be stored for up to 12 weeks under optimum storage conditions. During storage, fruit should be inspected often for signs of decay or disorders.
Uses and by-products
Oranges can be consumed as fresh fruit and are commonly pressed or squeezed to produce orange juice. The raw juice constitutes about 50% of the processed fruit, the peel residue, and the seeds are the major products or by-products and from these sources a lot of industrial products are derivable. For example, single strength (natural) fruit juice, concentrated juice, fruit powders, and orange flour are some of the major industrial products derived from the raw juice. Also, the pressed peel, citrus pulp and meal peel oil, citric and lactic acids, brandy spirit, feed yeast, vinegar, marmalade, candied peel, and citric pomade are products derivable from peel residue. Products derivable from the seeds are seed oil and meal
Opportunities for investment in Nigeria
Sweet orange is one of the most consumed fruit in Nigeria. Due to the rapid increase in population, there is an upsurge in demand for oranges. With the high consumption rate, there is an increased opportunity for investors and producers. You can make millions in the orange orchard business, with good planning and hard work. Decide on the variety to plant, but make sure they are disease resistant and fast growers and fruiters. Irrigate properly and maintain your orchard. Be prepared against diseases and harvest early.
Available market
You can sell your ripe fruits to middlemen or sell directly to the retailers. You can sell your quality fruits to beverage companies and grocery stores. You can also process into jams, candied oranges, marmalade, etc. You can also sell to animal feed production companies.
Financial implication
Orange farming requires significant investments. The land will take up a major part of your expenses. But if you have land to use, then you would have saved yourself a significant expenditure. For land located in the cities, you may have to spend between N2, 000,000.00 to N10, 000,000.00 per plot. Those located at the suburbs are significantly cheaper and may cost from N200, 000 to N2, 000,000.00 per plot. Fencing the farm and providing a source of water for irrigation are important expenses. Cost of labor to prepare your land. This varies depending on location.
The cost of seedlings is another very important expense. If you prefer to buy young trees, they can go from N800 to N1, 500 per stand. Multiplying these by the number of stands you need will give you a figure. The best part of this investment is that it is a one-time investment that needs not to be repeated unless you want to plant more citrus plantations.
Challenges of orange production in Nigeria
One of the major challenges of orange production is lack of value addition resulting in post-harvest wastage of these important fruits. Lack of infrastructure for storage and preservation, lack of improved varieties, poor R&D funding, and poor handling of the fruits during harvesting and transportation (link earlier article on post-harvest handling of oranges).
Opportunities in this sector
Great opportunities for investment abound in the orange production value chain. The area of post-harvest processing, packaging, and storage has not been fully explored. There are also other areas along the orange production value chain that one can invest in.
References
‘Orange’. Accessed from https://plantvillage.psu.edu/topics/orange/infos on 26th December 2019
Abah H. (2017) Juicy orange business in benue. Retrieved from https://www.benuenews.com.ng/2017/01/juicy-orange-business-in-benue.html on December 20, 2019.
Citrus production, Nigeria. retrieved from https://www.gistmania.com/talk/?action=gallery;sa=view;id=64243 on Decemeber 24, 2019.
Citrus programme. NIHORT. Retrieved from http://nihort.gov.ng/research.aspx?uid=001 on December 25, 2019.
Eno Johnson (2018) Lemon and Orange Farming in Nigeria. Retrieved on 26th December, 2019 from https://www.enibest.com.ng/all-posts/agriculture/orange-farming/
Etebu E and A. B. Nwauzoma (2014). A review on sweet orange (Citrus sinensis Osbeck): health, diseases, and management. American Journal of Research Communication, 2014, 2(2): 33-70} www.usa-journals.com, ISSN: 2325-4076.
Feng Choji. How to start lemon and orange farming in Nigeria. Retrieved from https://www.wealthresult.com/agriculture/orange-lemon-farming-nigeria on 26th December 2019.
Okaria Odili Frankline. How to start orange plantation in Nigeria: Step to Step guidelines. Retrieved from https://www.entorm.com/agriculture/orange/ on 27th December, 2019
Olife I.C, Ibeagha O.A., and Onwualu A.P. (2015). Citrus Fruit Value Chain Development in Nigeria. Journal of Biology, Agriculture and Healthcare Vol. 5, No. 4: 36-47
USDA Nutrient database (2014). United States department of agriculture, national nutrient database for standard reference release 26, Fruits and fruit juices.
Written by Olanrewaju Rukayat I.
