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| Thursday, 19 August 2004 |
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Resurrection of sweet orange industry in Sri Lanka by Dr. P. M. Wijeratne, Deputy Director (Research), Regional Agricultural Research and Development Centre, Bandarawela and M. G. B. Hemachandra, Research Officer-In-Charge, Agricultural Research Station, Rahangala Sweet orange cultivation in Sri Lanka is distributed over 20 districts with the majority of areas confined to rainfed areas predominantly in Moneragala, Badulla, Anuradhapura, Kurunegala and Kandy districts. In other areas of the country scattered trees are found in the home gardens. It is believed that sweet orange has been grown in Sri Lanka from time immemorial although the exact beginning cannot be traced back. The present global production of sweet orange is about 50 million tons and according to FAO (2001), world production of sweet orange has increased by 36-54% from 1975 to 2000. Unfortunately the sweet orange production in Sri Lanka has kept a low phase because the early agricultural policies in the country reflected more concern for peasant cultivation such as rice and other field crops without much attention for the development of fruit sector. In this scenario the current extent of sweet orange cultivation is about 3,500 ha with the annual average yield of about 1.7 mt/ha which is far below the average yield of 40 mt/ha in the major citrus growing countries. Currently Sri Lanka imports annually about 12,000 mt of sweet orange to meet the local demand. It may be observed here that more than 90% of the world sweet orange production is confined between latitudes 20 degrees and 40 degrees in both northern and southern hemispheres and only 10% between the latitudes 20 degrees north and south of the equator. Thus Sri Lanka being situated between 6 degrees to 10 degrees north of the equator, does not come within a normal orange growing belt and the success of any large scale cultivation within her latitude is problematical. However, there are certain factors which counteract this apparent disadvantage to a considerable degree as the country possesses in its highland areas the environmental conditions which approximate the temperate climate thereby providing suitable conditions for orange production. History There are reports to indicate that the cultivation of sweet orange has been attempted by the British residents in Sri Lanka as far back as 1850s during colonial times. During this period small quantities of budded or grafted seedlings of sweet orange, grapefruit and mandarin had been imported and tested for their adaptability with no success. However, by 1880 there has been a continuous supply of locally grown sweet orange fruits to the Colombo market which indicates that the subsequent efforts made for the expansion of sweet orange cultivation have been fruitful. We have a copy of an interesting article addressed by Mr. W. Ferguson to the editor of the Observer in 1881 which says that there has been a flourishing sweet orange plantations in certain areas in Galaha, Hatton and Maskeliya. It appears that during this period citrus cultivation has not been attempted as a monocrop under large scale cultivations but as isolated plants growing around houses and as avenue plants along the roadsides and borders of coffee and tea plantations. Unfortunately towards the end of the 18th century a disaster befell and all the trees destroyed by a disease unknown at that time. The Department of Agriculture was formed in 1912 and the first technical attempt on sweet orange cultivation was made in 1913 with the importation of seedlings which were subsequently tested for their adaptability in different locations in Colombo, Kandy and Kegalle districts. During the following years, the research attention has been focused on various aspects of production technologies including the identification of rootstock varieties suited for varying conditions of climate and soil types, insect pests and disease management and the tree management technology etc. Ultimately these efforts were paid back with flourishing sweet orange and lemon cultivations established in Badulla and Moneragala by the year 1940. The varieties planted include Kotte orange, Copai orange, Sathudi orange, Vavuniya orange, Omanthai orange and Bibile sweet. However, in 1950s all the trees began to become unhealthy and the yield began to decrease. Within a period of ten years all the plantations except for the few trees in the home gardens collapsed. This spelt a great disaster for the whole sweet orange cultivation in Sri Lanka. The government in power at that time obtained the services of the foreign experts to find out the root course of the problem and make recommendation for resurrection of the sweet orange industry. The experts, who investigated into the problem, were of the view that the collapse of citrus industry is not only due to tristeza virus (as it had been speculated at that time) but also due to unscientific site selection, negligence of after care operations and nutrient deficiencies etc. When considering the soil types, rainfall pattern and the temperature regime in the area, it is doubtful if the district of Moneragala is a suitable area for citrus cultivation. The soil in this area is comparatively shallow with the bedrock lying about one meter beneath the soil surface. Such a soil type would undoubtedly interfere with the normal growth of the root system. The high temperature during bloom could cause significant yield reductions; insufficient moisture could also have detrimental effect on yield. In this scenario the success of orange cultivation on any large scale in this area could be problematical. It is of course by chance that Sri Lanka once had a flourishing citrus cultivation in this areas. There are however highland areas in the country with optimal rainfall, temperature regimes and good soil types that can be utilized for the cultivation of high yielding sweet orange and mandarin varieties which are currently available with the Department of Agriculture. The resurrection of this industry would first of all require the development of cultivars that perform well in the local environment and the improved production technologies such as the site selection, water requirements, nutrient management, insect pests and disease management, tree management and the post harvest handling of the fruits. Sweet orange cultivars There are four major types of orange varieties in the world; round orange, navel orange, blood orange and acidless orange. Of these a navel orange cultivar namely Arogya which is suitable for the upcountry intermediate zone has been released by the Department of Agriculture in the year 2001. Fruits of this cultivar are seedless and are larger than those of other sweet orange cultivars (Bibile sweet and Bibile seedless) grown in Sri Lanka. The presence of limonin a compound that when oxidized impart bitterness to juice, generally limits the use of this cultivar for processing. This cultivar bear fruits after 3 years of planting and a single plant produces about 300 fruits per year. Round orange Under this category there are 2 cultivars namely, Bibile sweet and Bibile seedless that have been commonly grown in Sri Lanka. The Department of Agriculture, after long years of experimentation at the Regional Agricultural Centres at Bandarawela and Rahangala, is ready to release yet another cultivars of round orange which can be successfully grown in many parts in Sri Lanka. They are Hamli, Velancia and Pineapple orange. These cultivars are specially suited for the up country intermediate zones where temperature difference between day and night could activate the pigmentation on the peel giving it an attractive orange peel colour. The fruits of these cultivars are smaller than the navel cultivar Arogya and are suitable for processing industry. All the cultivars bear fruits after 3 years of planting and a single plant could yield 400 fruits per year. In order to retain the desired characters the budded or grafted seedlings should be used for cultivation. Thus the production of large scale disease free planting materials is the single most important step to lay the scientific foundation of the future citrus industry. It involves a number of steps such as potting mixture sterilization, budwood and rootstock selection and virus diagnosis etc. These methods of asexual propagation could upset the characters of the plant by the interaction of the scion and the stock plants and therefore, this problem has received much attention in the past. The most hardy and vigorous rootstock suited for our conditions and the cultivars mentioned above have been identified. For, example, Philippine red lime is the most suitable stock variety for Arogya and the rough lemon is the most suitable variety for the round orange cultivars mentioned above. There are trained registered nursery men capable of producing good quality planting materials. In addition the Regional Agricultural Research and development Centre, Bandarawela and its sub station located at Rahangala have already initiated a planting material production programme. Technical know-how Sweet orange unlike many other crops requires careful attention. Therefore, it is extremely important to educate the growers on all aspects of production technologies from the site selection up to harvesting and processing. It should be mentioned that Sri Lanka possesses all what is required to elevate the sweet orange industry to a level of commercial importance. There is no doubt that the Sri Lankans will be fortunate to see the market shelves full of yellow colour local sweet orange fruits the place now being occupied by the fruits imported from other countries. |
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