Since the introduction of Hevea brasiliensis (rubber) to Malaysia in 1877, there had been a rapid increase in the land under this crop. It reached a peak of over 2 million hectare at one time after which the area declined to the current figure of over 1.8 million hectares. Nevertheless, the yield per unit area increased considerably at the same time, it being more rapid in the last two to three decades. These increases in productivity are mainly the outcome of innovations emanating from RRIM, complemented by contributions from the private sector, and extension and development agencies. However, the industry experienced low total production in 1993 owing mainly to reduced tapping because of low prices.

In addition to increases in yield and productivity, research innovations also included issues of early returns to investments, reduced labour requirement, and conservation of the environment. Admittedly, agencies other than RRIM also contributed to the development in production research in rubber.

Through breeding and selection of new clones and improvements in agronomic practices, it has been possible to increase the yield over time. It has been observed that yield increase due to improved agronomic practices was as high as that obtained through breeding.

The yield increase obtained through breeding and selection is a high achievement considering that the current genetic potential of over 3500 kg/ha/year has been achieved by the use of only a very limited number (21) of seedlings originally introduced into the region.

In the earlier years of breeding, the emphasis was on total yield over the life of the planting. This approach continued into the 1960’s when the currently dominant clone, RRIM 600, was produced. With increasing concern for quicker returns to investments, selection criteria emphasised on precocity (early high yields) in addition to total high yield and related secondary characteristics. The precocity of yield of the newer clones in now reflected in a yield of about 9200 kg/ha in the first five years.

In the smallholder sector, RRIM clones account for a larger percentage of planted area. It is also a well accepted fact that in at least one neighbouring country, RRIM clones dominate their large planted areas of smallholdings. In the estate sector, clones produced by the private sector (e.g. PB clones) have dominated in the past.

Due to wide variability in management practices and, to a lesser extent, soil and climatic conditions, the genetic potential of the existing commercially planted clones is not fully achieved. For example, in 1985 the average yield per tapped hectare in selected estates was 1535 kg. Yet, these yields varied from a low of 1440 to a high of 1940 kg/ha. The data reflected that even in the mid- 1980’s there was a gap between the average yield in experimental plots (about 2500 kg/ha) and the best managed estates (about 1900 kg/ha); such differences exist in other crops too, as, understandably, scales of operations vary. However, the low national average yield of 1100 kg/ha in 1985., for example, reflects that the industry was short of the commercial potential of 1900 by about 800 kg/ha/year. In short, the research outputs on improved genetic material and agronomic practices have bot been fully utilised. Breeding for newer clones has progressed relatively fast, despite the fact that Hevea is a tree crop. In the earlier years, breeding for newer clones generally took 30-40 years from the production of hand-pollinated seeds to the evolution of the release of new clones for commercial planting. Newer approaches in breeding and selection programmes have now resulted in the cycle being shortened to one of 20 to 25 years. Efforts in hand aim at reducing the selection cycle even further.

Conventional breeding programmes involving cross-pollination of selected parents and ortet selection, especially from commercial plantings of seedlings obtained from natural pollination in polyclonal seed gardens, have been the main basis for obtaining new clones for many years. The recent developments of tissue culture techniques enabling the production of transgenic Hevea plants etc. have now opened up new potentials.

Whilst these developments were taking place, the need to widen the very narrow genetic base of Hevea for breeding from the limited 21 seedlings originally introduced to the region was realised. RRIM, subsequently, either on its own or jointly with others – nationally or internationally – mounted expeditions to collect new genetic materials from the Amazon Jungle of Brazil, the origin of natural rubber.

Various aspects of propagation have been addressed and many improvements introduced.

For a long time since the inception of using clonal materials, budding of field planted seedlings about 15 to 20 months after planting was the norm. Subsequently, in the early 1960’s budding of plants on about two to eight months old seedlings, known as "green budding," was introduced and this became the accepted practice. Later developments led to techniques for budding on seedlings of three to five months. Additionally, research findings led to field planting (field budding being changed to budding in the nursery, either in the ground nursery and transferred to polybags as budded stumps or by raising seedlings in the bags for budding) and transplanting in the field as one to two whorled plants.

The various techniques developed were implemented and effects evaluated by the commercial sector. Early results showed that the newer techniques of green buddings in intensively managed nurseries and transplanted as two whorled plants not only came into tapping earlier (in 59 months as opposed to 67 months) but also gave higher initial yield.

By early 1970’s, green budding gained dominance and by mid – 1970’s green budding in bags and transplanting as one to two-whorled plants became the norm. At the same time investigations on the use of more advanced materials were mounted. The initial results indicated that more advanced materials such as four to five-whorled plants raised in polybags gave better performance.

Though research showed that the use of a more advanced planting material, namely stumped budding, gave higher yield that the five-whorled plants used, the former has not gained acceptance owing to problems of logistics of field operations. Nevertheless, polybag-raised young buddings of two to five whorls are now a common feature.

The potential of a given clone is best realised with optimal agromanagement where soil management and fertiliser use are the important components. In Malaysia, even with an average of 20% yield increase to fertilisers alone (i.e. excluding other inputs and thus the additional yield from them) accounted for 50% of the increased net profits in the commercial estates evaluated. The approach to fertiliser use is on a discrimanatory basis and dependent on soil and foliar analysis interpolated with clone, yield and potential yield, and the knowledge of management practices. This approach is based on proven relationships between responses and nutrient contents of soil and plant.

In addition to fertilisers, the value of establishing and maintaining a legume cover has been shown to affect productivity. Legume covers not only allow increased growth, and subsequent productivity, and reduced requirement for nitrogen but also conservation of nutrients and physical properties of soil and reduced incidence of root disease. The importance and benefits of legume covers and manuring from early immaturity on initial as well as subsequent yields are generally accepted by the industry. The use of legume covers and proper fertiliser inputs in immaturity are well accepted in most rubber replantings on estates, schemes and group replantings where it is a common accepted practice.

The use of ethephon as a yield stimulant is undoubtedly a significant contribution to enhanced exploitation of Hevea. The use of ethephon has enabled early exploitation of trees (e.g. even trees with girth of 43 cm or more) and allowed the development of periodic system of tapping which enables reducing loss of crop due to loss of tapping days to rain, or even stop-page of tapping, say, during fruit season, etc. It also helps to earn higher yields from older trees.

The advent of ethephon has also enabled earlier exploitation of trees at girths smaller than conventional girths. A minimum of 50 cm was for long considered the norm before exploitation could commence. However, some commercial areas were exploited in the early 1960’s at girths of 45 cm. Subsequent investigations by RRIM confirmed that this was physiologically acceptable, provided adequate management inputs were supplied. In fact, with controlled use of low concentration of ethephon, trees of girth of 43 cm or over are being exploited economically.

INCREASED PROFITABILITY

Reduced Unproductive Phase

A number of practices have been introduced to reduce the unproductive phase of the trees and thus increase profitability. These include inherent properties of clones, planting materials, management practices and exploitation systems.

The newer clones are more vigorous and tappability (at 50cm girth) could be achieved in 4.5 to 5 years compared to a period of 5.5 to 6.0 years for older clones. A recent study showed that the newer clones now being made available are more profitable than the older clones.

The factors contributing to earlier monetary returns, and thus also higher economic returns, are however dependent not only on clonal vigour but also on precocity of yield, i.e. initial high yields.

With increasing labour wages and with lack of available labour for the plantation sector, the need for labour saving approaches were addressed. Many of the research findings of RRIM and others are now in use.

Shortage of labour, especially skillled tapping labour, became an increasing constraint from the early 1970’s. Thus, research on less labour-intensive systems of exploitation were intensified and new systems emerged. However, a major drawback is that the new clones do bot lend themselves to be exploited by any non-conventional systems.

Nevertheless the introduction of ethephon stimulation has enabled the development of lower intensity systems. With lower frequency of tapping, labour intensity is reduced and area covered per tapper increased.

Up to the early 1970’s almost all estates followed the d/2 frequency (once in two days) of tapping for buddings; but currently d/3 frequency (once in three days) is a common feature for tapping. The use of ethephon allows further reduction to d/4 (once in four days) or maybe even to d/6 (once in six days). However, to obtain acceptable yields, these low-frequency systems are introduced from the commencement of tapping.

The current investigations indicate some potential for the development of long flow systems, which, in addition to increased yield, could lead to less labour-intensive system, e.g through increased tapping task etc.

In addressing the issue of shortage of skilled tapping labour, RRIM has considered the use of mechanised tapping knives, auto-tap (using mechanised tapping knife attached to trees), collection of latex by pipe systems and many others. So far, the research has not provided a practical application system but such approaches may provide a solution by the turn of the century.

Crop protection is one aspect that includes control of both weeds and diseases.

Several diseases, often localised, are known to affect some clones more than the others. The most important diseases are Oidium hevea, Phytophthora botryosa and Colletotrichum gloeosporioides, with the first affecting not only growth but also yield. The type of control developed in RRIM and the economics are well documented.

Localised occurrences of these leaf diseases can be serious. Oidium, for example, affects yield. For long the conventional control measure was sulphur-dusting using a shoulder or tractor-mounted motorised duster. The duster could cover about 20 ha per day. Research led to the development of oil-based formulations for Oidium control, whereby, for example, fogging with tridomerph-in-oil at 5 kg per round per hectare was required. The mechanical fogging allowed a coverage of 100-150 ha per day. It requires not only less labour but also less chemical and the cost is about 30% of the conventional sulphur-dusting.

In addition to diseases, weed competition adversely affects growth and productivity of rubber. At the same time, control of weeds accounts for over 30% of upkeep costs of young rubber. Research has successfully addressed the issue of choice of chemicals and applicators to increase the effectiveness of weed control while at the same time reducing costs. The findings are now a common practice in the field.

Weed control especially during the immature phase of rubber in the 1970’s accounted for about 30% of total upkeep cost. Conventional knapsack spraying was bot only labour-intensive but also costly. Research and development work by RRIM, often jointly with the industry (including the rubber and chemical market industry), led initially to the use of the tractor-mounted motorised sprayer and later to the controlled droplet applicators. It has been shown that the newer systems reduced labour and chemical usage.

Research at RRIM has often consciously addressed the issue of safe-guarding the environment.

Large amounts of fund have been spent in expeditions to the Amazon basin to collect germplasm. The collections are now maintained in germplasm ‘gardens’ at a considerable cost.

Based on reasearch and demonstrations, from the early years of commercial cultivation of rubber, the use of terracing for conservation on sloping lands is an accepted practice both in the estate and smallholders sectors. In addition, the use of legume covers enhances soils physical properties, reduces erosion losses to almost nil on full establishment and reduces leaching of nutrients to lower depths.

For long, sodium arsenite was the main chemical used for weed control in rubber. An exception was water catchment areas where its use was banned. Realising the very harmful effects of sodium arsenite to both the handlers as well as the environment, RRIM mounted intensive efforts to find an economically and environmentally acceptable alternative. A combination of 2,4 D-amine and sodium chlorate with other chemicals in different rates was subsequently found to be a satisfactory alternative. Currently, non-toxic chemicals such as alachlor etc. dominate the chemicals used in the rubber industry.

In disease control, e.g for Oidium, sulphur-dusting was replaced by oil-based formulations, e.g. of tridomorph. However, this is more an emergency measure, as disease avoidance is the major approach which has been introduced. In this approach, based on climatic factors and study of disease outbreaks, the country has been categorised into planting regions for rubber. Additionally, all clones are screened for the major diseases. The final selection of clones for commercial planting therefore is based on avoiding susceptible clones in areas where the disease outbreak is likely. Similarly, an environmental approach is being considered for resistance to South American leaf Blight. Currently, in Brazil to combat the disease, regular spraying is needed. Breeding for full resistance is not possible as the pathogen mutates. Thus, an approach of field resistance is used, and most of RRIM and other Malaysian clones have been screened for such resistance. In addition, nutrition of trees as a means of overcoming severity of infestation, e.g. due to Oidium etc. is practised.

Large quantities of effluents (process waste) emanate in the processing of rubber. In the earlier years, these effluents used to be discharged indiscriminately into water ways. In the 1970’s biological treatment of effluent (through anaerobic and aerobic digestion) was developed. The treatment of effluents before discharge is now an accepted practice and is governed by clear guidelines from the Department of Environment. At times the effluent is recycled and used as source of nutrients for crops.

The confirmation by RRIM on the need for early treatment of the felled rubber trees to convert the trunks into valuable medium hardwood timber opened up a huge potential. Currently, in Malaysia alone there is over 1.8 million hectare of rubber which forms large planted plantation forests. In addition to contributing to reduction in CO₂ build-up, rubber plantings also reduce pressure on natural forests.

Continued and enhanced progress in all facets of production in crucial to a viable rubber industry, at least in meeting Malaysia’s own needs for NR in the manufacturing sector.

Of crucial importance is less labour-intensive systems, particularly in tapping. A system amenable to, say, exploitation once a week on a simple puncture(s) system, appears to mind. Can such a system work on existing clones selected on responsiveness to a 1/2S system? Will a clone produced from the 1981 germplasm collection come with a winner by the year 2020?

Mechanisation appears to be also an important component. This holds promise in areas of land preparation (already in vogue) and, more importantly, in transplanting of more and more advanced materials. In addition, mechanisation including robotics has a key role in tapping and collection and this is being pursued with vigour.

Concurrently, the approach to rubber as a monocrop, solely for latex, is slowly phasing out. It appears that rubber trees will be planted for the timber as a primary product and latex will only be an important byproduct which will pay for the upkeep of the stands until they are harvested for timber.

Breeding and selection may also address rubber trees as a source of components other than rubber hydrocarbons or timber. Hevea may be grown solely for the rubber clones, which have a higher hydrocarbon, in dense stands for mechanical harvesting of shoots followed by chemical extraction. In the smallholder sector, integration of other tree crops with rubber, possibly in avenue planting, may be of common occurrence by the 2020.