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| Wednesday, 16 June 2004 |
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Developments in rubber agronomy inadequate to meet challenges by Dr. N. Yogaratnam,
Although after privatisation of estates in 1993, there has been an upward trend in production, registering 112,600 MT in 1997, but with the South - East Asian financial crisis in July 1997, the rubber prices in the world market slumped by about 50 percent which again had a negative effect on rubber production in Sri Lanka. Over the past few months from about June 2003 prices began an upward movement which culminated in all - time high price last week at the Rubber Auctions in Colombo. The net sales average (NSA), per kilo now stands at around Rs. 120 and the cost of production (COP) at estate level is approximately Rs. 80 per kilo. This is indeed a happy position to be in and all indications are that these price levels would be sustained and perhaps improved in the weeks and months to come. Yield gaps Nevertheless, Sri Lanka had not been a major producer nor an important exporter of natural rubber. Production decreased to such an extent that our rubber hardly found an overseas market. To add to these woes, Thailand, Malaysia, Vietnam and India are the major production locations with yields of over 1,800 kilos per hectare annually. Sri Lanka's production stands at about 750 kilos per hectare. As of now, Sri Lanka occupies the eighth position in the world's NR supply, way behind the three South East Asian economies, Thailand, Indonesia and Malaysia and also India. Total NR Production in major rubber producing countries Country 'ooo tonnes/Yr. Thailand 2,346 Indonesia 1,556 India 629 Malaysia 615 China 445 Vietnam 269 Sri Lanka 92 Philippines 67 Nigeria 63 Rest of the world 733 Although significant progress has been made towards increasing rubber yields in Sri Lanka, there still exists wide yield gaps. Nevertheless, given the operational skills of estate personnel under private sector management, it will not be difficult to sustain a level of productivity which is in close approximation to the maximum attainable under experimental conditions. Rubber Breeding & Selection Several advances have been made in rubber breeding and selection in Sri Lanka. A large number of high yielding clones have been successfully developed over the years. Of those the most outstanding are the RRIC 100 series clones. This series has been developed with emphasis on higher yield as well as favourable secondary characters of economic importance such as vigour, resistance to leaf diseases and resistance to wind damage. The RRIC 100 series clones is known to reach the tappable girth 6 to 12 months earlier than the PB 86 which was the best primary clone grown traditionally in Sri Lanka. Among the RRIC 100 series clones, RRIC 100, RRIC 102 and RRIC 121 have now gained wide popularity in both estate and smallholder sectors. The average annual yield (first 8 - 10 year averages) that can be obtained from the above tree clones are around 1600 - 2500 kg/ha. Few other very promising clones from this series are the RRIC 117, RRIC 130, RRIC 131 and RRIC 133. RRIC 130 appears to be very high yielding clone, particularly in the initial years of tapping. At experimental level, it has given an annual yield of 4662 kg/ha of dry rubber in the initial two years of tapping. The new additions to the pool of genetically improved rubber planting material in Sri Lanka are the RRISL 200 series and RRISL 2000 series, the yield potential of which are expected to be approximately 25-30% higher than the RRIC 100 series clones. Although, the productivity potential of planting materials developed in from competing countries is of a much lower order, their national level production is much higher than in Sri Lanka, as reported earlier. Latex - Timber Clones There has been a great demand for rubber wood largely by furniture manufacturers. Rubber growers were, therefore, looking for clones that produce both high latex yield and timber yield. The need to produce latex - timber clones for a multifaceted rubber industry in the future has been recognized. Among the RRI clones, RRIC 133 and RRIC 121, RRISL 205 and RRISL 2000 and 2001 have been identified as good latex timber clones for planting. Both these clones possess a very vigorous growth with strong and straight trunk - characteristics that are ideal for timber production. In order to extend the range of clones under this category, two clones introduced from Malaysia, namely, PB 235 and PB 260, have also been tested under Sri Lankan conditions. Conservation and Evaluation of the Hevea Germplasm: Conservation of germplasm is integral to genetics improvement programme of any crop species. This has a particular importance to rubber breeders since available genetic base of rubber is very narrow as it originated from less than 2000 plants introduced in Sri Lanka in 1876. Extensive genetic advances made by directional selection for high yield and growth over last decades have caused a loss of other valuable genes which were available in the old clones as more productive clones take their place. In an effort to conserve genes present in the wild, RRISL has established Hevea germplasm collection comprising few genotypes collected from the Amazon basin. In the preliminary evaluation of this collection, two promising clones, GPS 1 and GPS 11 had already been identified. Nursery Techniques and Management One of the reason for the present low yield levels is the use of inferior planting materials. The aim should be to achieve 500 healthy and vigorously growing plants capable of giving high yields in every hectare. Moreover, the current COP and rubber prices demand a productivity of approximately, 2500 kg/ha. Therefore, all new clearings should be capable of giving such yield levels for the rubber industry to be viable. "Young Budding", a technique where planting materials are raised by green budding very young stocks grown in polybags is now popular in Sri Lanka. This technique is known to be effective in terms of cost and agronomic performance. Development of cost effective and efficient plant propagation and planting techniques and after care operations that are required to ensure vigorously growing uniform stand of plants that can reduce the immature period of rubber considerably should be given high priority. Integrated Soil and Plant Nutrition Management System Significant developments have been made since late 70s in improving soil fertility, increasing efficiency of nutrient uptake, economising on fertilizer use improving methods of soils, water and nutrient conservation and weed management. While fertilizer misuse can contribute to environmental contamination, it is often an indispensable source of the nutrients required for plant growth and production. Unless the soil nutrients removed with the harvest yield are replaced in proper amounts from both inorganic and organic sources, crop production cannot be sustained. Soils fertility will decline. In the past, the emphasis has been on increased use of fertilizer; the approach now shifts to educating growers to use inorganic, organic and biological fertilizers optimally. Many plantations have completed three planting cycles of approximately 30 years per cycle. During this period, the commercial yields have risen from about 350 kg/ha to about 2500 kg/ha. With stimulation, nutrient drainage has become a still more significant factor. Development of degraded soil is another crucial aspect. Rubber nutrition therefore requires the judicious and integrated management of all sources of nutrients in rubber plantations. Prevention of erosion is equally important for maintenance of soil fertility and environmental protection. Reduction in the frequency of application of fertilizers to save few rupees on labour would be detrimental to both the soil as well as the plants on the long run. It would result in the risk of waste through leaching erosion, surface-run off and even scorching of immature plants if the weather turns to be unfavourable and therefore should not be practised. It is advisable that the annual requirement of fertilizers to immature rubber be split and applied in as many doses as possible. The frequency of application may be reduced without harmful consequences, when weather conditions are expected to be favourable. Soil scientists should bridge the research gap that still exists by developing appropriate integrated soil, nutrient and moisture management technologies for rubber based mixed cropping systems. The indiscriminate removal of large amount of mineral elements with the harvested intercrop can pose the problem of a marked mineral deficiency, although mutual benefits are also known to exist for a short period. The developed package should include recommendations for rubber as well as for the intercrops under such cropping systems. Pioneering research rather than duplication should be encouraged. Mixed Cropping It is known and accepted that rubber could be intercropped to optimise land use and hence to enhance profitability. Both short-term and perennial crops could be planted in this regard. The spatial arrangements of rubber could be adjusted to suit the intercrop. Research has shown that it would be possible to interplant rubber with tea without any adverse effects on either plant, provided the recommended spatial arrangement and other agronomic practices are followed. The Benefit Cost Ratio, Net Benefit Investment Ratio and Internal Rate of Return, are expected to be in the region of 1, 2, 3.73 and 31% respectively. Pests & Diseases Rubber plantations in Sri Lanka are susceptible to incidence of more than 20 diseases of which 6 diseases, namely, White root disease, Black root disease, Colletotrichum leaf disease, Phytophthora leaf fall, Corynespora leaf fall and Black trips have been identified as potential threats. The management strategies developed involve integrated control programmes by cultural, biological and chemical means with high priority for prophylactic measures. The pre-disposing factors conclusive for the out break of each pest and disease should be identified and prophylactic treatments adopted. Harvesting Exploitation of rubber tree continues to be a crucial element governing the productivity of rubber lands. Unfortunately, there is not one tapping system that will give the best results on all cultivers and under all conditions. In time of low rubber prices and high wages, the yield per tapper is of greater importance than the yield per hectare. Hence, tapping systems which give a high yield per unit of labour are of considerable economic importance. The main goal in developing new technologies should be to lessen the number of tappers needed and boost the income of those who remain. That's a critical issue. Conventional systems should give way to innovative technologies that are in practice in competing countries. In conclusion, the sustainability of rubber industry should be assessed using the basic pillars, namely, productivity, protection (of natural resources and environment), stability, economic viability, social acceptability and political supportability. If any of these elements is lacking, sustainable development will not be achieved. Economic viability, is linked to prices. For a perennial crop like rubber, which has a long unproductive period, its supply cannot be regulated on an annual basis according to changing market conditions. The time lag between use of input materials and appearance of response is also long. Furthermore, the competition from substitutes, notably, synthetic, tend to aggravate the situation. In the strategy to increase production, all three aspects, increasing productivity, restoring productivity and preventing deterioration of productivity are important. |
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Produced by Lake House |
Rubber plantations still remain vital in the economy of Sri Lanka.
Rubber production in the country was at its maximum of nearly 155,000 MT
in 1978. The fragmentation of estates in 1975 and subsequent neglected
management however caused a steady decline in production, reaching a low
level of 105,000 MT in 1993.
