Para Rubber Research Articles

Soil characteristics under cash crop farming in upland areas of Sarawak, Malaysia

This study discusses soil fertility under perennial cash crop farming (para rubber, Hevea brasiliensis; black pepper, Piper nigrum; oil palm, Elaeis guineensis) conducted by local farmers and an oil palm estate in an upland area of Sarawak, Malaysia, in comparison with the surrounding secondary forests. In the farmlands of the local farmers, rubber farming was conducted without fertilizer application, while 2–5 t ha −1 of NPK compounds were applied annually on pepper farms. Soils under rubber farming were acidic with poor nutrient contents, resembling soils in secondary forests. In pepper farms, soils were less acidic and showed high nutrient contents, especially with respect to available P and exchangeable Ca. This trend became stronger with increasing farming duration. Fertilizers applied around pepper vines appeared to migrate and spread across the fields. Bulk density and hardness of surface soils were higher in pepper farms than in secondary forests, indicating soil compaction due to field works. In the oil palm estate, annual fertilizer application rates were moderate at 0.4–0.8 t ha −1 of NPK compound fertilizers. However, the soil properties in the oil palm estate were similar to those of the small-scale pepper farms. Close to the bases of the palms where fertilizers usually are applied, the contents of exchangeable Ca and available P were high. Nutrient uptake by the dense root systems of the palms seemed to prevent excessive loss of nutrients through leaching. Loss of soil organic matter and deterioration of soil physical properties were brought about by terrace bench construction, but the soils seemed to recover to some extent over time. In conclusion, technologies such as intercropping and the appropriate allocation of different crops to specific locations as well as the proper selection and dosage of fertilizers should be developed and adopted to improve fertilizer efficiency and prevent water pollution due to fertilizer wash-off from farmlands.

Carbon stock assessment and soil carbon management in agricultural land‐uses in Thailand

AbstractThe organic carbon pool in agricultural land‐uses is capable of enhancing agricultural sustainability and serving as a potential sink of atmospheric carbon dioxide. A study was carried out to estimate and map carbon stock of different agricultural land‐uses in a sub‐watershed of Thailand and to assess the land‐use sustainability with respect to carbon management. A quadrat sampling methodology was adopted to estimate the biomass and its carbon content of 11 different land‐uses in the study area. Existing soil data were used to calculate the soil carbon. GIS was used for integrating biomass carbon, soil carbon and carbon stock mapping. Roth carbon model was used to project the soil carbon of present land‐uses in the coming 10 years and based on which the sustainability of land‐uses was predicted. The total carbon stock of agricultural land‐uses was estimated to be 20·5 Tg, of which 41·49 per cent was biomass carbon and 58·51 per cent was soil carbon. Among the land‐uses, para rubber had the highest average biomass C (136·34 Mg C ha−1) while paddy had the lowest (7·08 Mg C ha−1). About four‐fifths of agricultural land‐uses in the watershed are sustainable in maintaining the desired level of soil carbon in coming 10 years while one‐fifths are unstable. Such information on carbon stock could be valuable to develop viable land‐use options for agricultural sustainability and carbon sequestration. Copyright © 2007 John Wiley & Sons, Ltd.

A convenient and efficient protocol for isolating high-quality RNA from latex of Hevea brasiliensis (para rubber tree)

Isolating high-quality RNA from latex of H. brasiliensis is a prerequisite to elucidating the molecular mechanisms of rubber biosynthesis and its regulation. Here, an improved protocol was developed for latex collection, transportation, storage, and RNA isolation. Compared with existing ones, our protocol eliminated liquid nitrogen for latex collection and subsequent low-temperature (− 70 °C) condition for latex storage, making it more convenient and feasible when latex was collected in remote sampling sites, and latex storage and RNA isolation were conducted in poorly-equipped laboratories. Different methods (UV absorbance scans, denaturing gel electrophoresis, autoradiograph monitoring of cDNA synthesis) were used to confirm the high quality of the RNA prepared with this protocol, whose usefulness was further verified by several practical applications, including construction of one high-quality cDNA library, cloning of the full-length cDNAs of 3 novel Hevea sucrose transporter genes, and semi-quantitative RT-PCR analysis of two rubber-biosynthesis essential genes and one sucrose transporter gene.

Guayule and Russian Dandelion as Alternative Sources of Natural Rubber

ABSTRACTNatural rubber, obtained almost exclusively from the Para rubber tree (Hevea brasiliensis), is a unique biopolymer of strategic importance that, in many of its most significant applications, cannot be replaced by synthetic rubber alternatives. Several pressing motives lead to the search for alternative sources of natural rubber. These include increased evidence of allergenic reactions to Hevea rubber, the danger that the fungal pathogen Microcyclus ulei, causative agent of South American Leaf Blight (SALB), might spread to Southeast Asia, which would severely disrupt rubber production, potential shortages of supply due to increasing demand and changes in land use, and a general trend towards the replacement of petroleum-derived chemicals with renewables. Two plant species have received considerable attention as potential alternative sources of natural rubber: the Mexican shrub Guayule (Parthenium argentatum Gray) and the Russian dandelion (Taraxacum koksaghyz). This review will summarize the current production methods and applications of natural rubber (dry rubber and latex), the threats to the production of natural rubber from the rubber tree, and describe the current knowledge of the production of natural rubber from guayule and Russian dandelion.

Inhibition of Colletotrichum gloeosporioides (Penz) Sac. causal organism of rubber ( Hevea brasiliensis Muell. Arg.) leaf spot using plant extracts

In vitro and in vivo antifungal evaluations were carried out on twenty-one plants selected from fourteen families on a folial pathogen of para rubber, Colletotrichum gloeosporioides (Penz). Sac. Extracts of Ocimum basilicum L. and Allium sativum L. exhibited total inhibitory effects on the mycelial growth of C. Gloeosporioides. An evaluation of concentration effects was carried out using four concentrations of five selected plants: A. sativum, Jatropha curcas, O. Basilicum, Vernonia amygdalina and Ageratum conyzoides. A. sativum and O. basilicum totally inhibited conidial germination 24 h after inoculation, and conidial germination in liquid amended media was recorded only in the A. conyzoides amended liquid media. An in vivo evaluation showed that treatment with 100% O. basilicum resulted in disease index (D.I) of 31.7% which was significantly lower than the control 65% D.I at 5% level of probability.

BOD5 Estimation by Using UV Absorption and COD for Rapid Industrial Effluent Monitoring

The study dealt with the method to predict the BOD(5) in effluent from industrial wastewater by using the UV absorption from two wavelengths, 260 and 550 nm. The interference from suspended solids was reduced. In the same time, COD was used as the secure value to calculate BOD(5). From the representative wastewater treatment plants, the estimated effluent BOD(5) of wastewater from the Para rubber industry showed an average error at +/-2.97 mg/l. While it was at +/-3.31 mg/l, for frozen seafood industry. The simple mathematic equations in this study gave the assuring method for BOD(5) estimation without time consuming.

Molecular phylogenetic analyses reveal a close relationship between powdery mildew fungi on some tropical trees and Erysiphe alphitoides, an oak powdery mildew

To investigate the phylogenetic relationships among the powdery mildew fungi of some economically important tropical trees belonging to Oidium subgenus Pseudoidium, we conducted molecular phylogenetic analyses using 30 DNA sequences of the rDNA internal transcribed spacer (ITS) regions and 26 sequences of the domains D1 and D2 of the 28S rDNA obtained from the powdery mildews on Hevea brasiliensis (para rubber tree), Anacardium occidentale (cashew), Bixa orellana, Citrus spp., Mangifera indica (mango), and Acacia spp. The results indicate that the powdery mildew fungi isolated from these tropical trees are closely related to one another. These powdery mildews are also closely related to E. alphitoides (including Erysiphe sp. on Quercus phillyraeoides). Because of the obligate biotrophic nature of the powdery mildew fungi, the relationship between powdery mildews and their host plants is conservative. However, the present study suggests that a particular powdery mildew species has expanded its host ranges on a wide range of the tropical trees. This article also suggests that a powdery mildew fungus distributed in temperate regions of the Northern Hemisphere expanded its host ranges onto tropical plants and may be a good example of how geographical and host range expansion has occurred in the Erysiphales.

Inhibition of Colletotrichum gloeosporioides (Penz) Sac. causal organism of rubber ( Hevea brasiliensis Muell. Arg.) leaf spot using plant extracts

In vitro and in vivo antifungal evaluations were carried out on twenty-one plants selected from fourteen families on a folial pathogen of para rubber, Colletotrichum gloeosporioides (Penz). Sac. Extracts of Ocimum basilicum L. and Allium sativum L. exhibited total inhibitory effects on the mycelial growth of C. Gloeosporioides. An evaluation of concentration effects was carried out using four concentrations of five selected plants: A. sativum, Jatropha curcas, O. Basilicum, Vernonia amygdalina and Ageratum conyzoides. A. sativum and O. basilicum totally inhibited conidial germination 24 h after inoculation, and conidial germination in liquid amended media was recorded only in the A. conyzoides amended liquid media. An in vivo evaluation showed that treatment with 100% O. basilicum resulted in disease index (D.I) of 31.7% which was significantly lower than the control 65% D.I at 5% level of probability.

Initiator-independent and initiator-dependent rubber biosynthesis in Ficus elastica

The rubber-producing tree, Ficus elastica (the Indian rubber tree), requires the same substrates for rubber production as other rubber-producing plants, such as Hevea brasiliensis (the Brazilian or Para rubber tree), the major source of commercial natural rubber in the world, and Parthenium argentatum (guayule), a widely studied alternative for natural rubber production currently under commercial development. Rubber biosynthesis can be studied, in vitro, using purified, enzymatically active rubber particles, an initiator such as FPP, IPP as the source of monomer, and a metal cofactor such as Mg 2+. However, unlike H. brasiliensis and P. argentatum, we show that enzymatically active rubber particles purified from F. elastica are able to synthesize rubber, in vitro, in the absence of added initiator. In this paper, we characterize, for the first time, the kinetic differences between initiator-dependent rubber biosynthesis, and initiator-independent rubber biosynthesis, and the effect of cofactor concentration on both of these processes.

Depolymerization of β-chitin to mono- and disaccharides by the serum fraction from the para rubber tree, Hevea brasiliensis

The serum fraction of latex from Hevea brasiliensis, the para rubber tree, is known to contain an endo-chitinolytic enzyme, hevamine. Herein the activity of the rubber serum towards β-chitin is investigated. The serum contained 6 mg/mL of protein and a chitinolytic activity of 18 mU per mg of protein. The optimum ratio of enzyme to chitin was 0.22 mU/mg, and the optimum substrate concentration was 60 mg/mL. The optimum pH range was pH 2–4, and the optimum temperature was 45 °C. At these conditions both (GlcNAc) 2 and GlcNAc were produced in a molar ratio of approximately 2:1. The hydrolysis of 300 mg of chitin with 64 mU of the rubber serum for 8 days under the optimum conditions gave 39 mg of GlcNAc and 108 mg of (GlcNAc) 2 as determined by HPLC. Mixing the rubber serum preparation with an Aspergillus niger pectinase preparation containing β- N-acetylhexosaminidase can be used to produce almost exclusively the GlcNAc monomer in about 50% yield.

Relationships among secondary forests and resource use and agriculture, as practiced by the Iban of Sarawak, East Malaysia

Previous research has dealt with the relationships between forests and the people living in and around forests practicing swidden farming, in tropical rain forest climates in insular Southeast Asia. It was pointed out that hill swidden farming with a long enough fallow period has been considered to be in harmony with the forest environment. However, there have been few studies on the relationships between forests, and resource use and agriculture as a whole. This paper, as a result of a case study in an Iban village in Sarawak, demonstrates that the Iban allow all their agricultural lands (swamp paddy fields, Para rubber gardens, fruit gardens, pepper gardens, and, of course, hill swiddens) to return to natural forests, or construct man-made forests that are similar to natural forests. In addition, considering other activities such as fishing, hunting and collection of forest products, it can be seen that the resource use and agriculture practices of the Iban are based on secondary forests. In resource use and agriculture, the natural, social and economic environments play important roles. One important natural factor is strong vegetation recovery. As the villagers recognized, when forests recover, thick weeds on agricultural lands disappear and the fertility and structure of soils are improved. After the return to secondary forest with a strong recovery of vegetation, agricultural land is opened again. The villagers benefit with less labor and capital, as tillage work and fertilizer application are not necessary. Large fluctuations in social and economic conditions outside the village affected the villagers’ attitudes toward resource use and agriculture. Within this setting, the Iban in Nakat have survived by rapidly changing activities regarding resource use and agriculture, adapting to the social and economic conditions of their surroundings. For the Iban, secondary forests have a high potential value. The secondary forests house plants and animals that are current and potential resources. These forests can also be easily converted to other kinds of agricultural use at a low cost. These are the reasons for the Iban’s secondary forest based resource use and agriculture.

Latex quantification in homogenate and purified latex samples from various plant species using near infrared reflectance spectroscopy

Parthenium argentatum (guayule) is under commercial development as a source of hypoallergenic latex, which is suitable for the manufacture of latex medical devices safe for use by people suffering from Type I latex protein allergy. Improving agronomic practices, post-harvest shrub handling, and optimizing latex extraction and purification protocols during bioprocessing are hampered by the relatively cumbersome latex quantification methods currently employed. Current methods require several hours before analytical results can be obtained. The object of our study was to develop and test a near infrared (NIR) spectroscopic method for rapid quantification of latex in both wet and dried P. argentatum homogenate and purified latex samples. The procedure was tested on latex samples from Ficus elastica (Indian rubber tree), Helianthus annuus (sunflower), Hevea brasiliensis (Brazilian or para rubber tree) and Taraxacum kok-saghyz (Russian dandelion). P. argentatum latex could be accurately quantified, over a wide concentration range of 0 to 25 mg/ml. The correlations between the measured rubber content and the rubber content predicted by NIR were 0.96 and 0.91 for dry and wet samples, respectively. The presence of homogenate components unrelated to the latex fraction did not perturb the correlations obtained. Similar predictive models could be used to measure the rubber content in F. elastica, H. annuus, H. brasilensis and T. kok-saghyz.

Transcriptome analysis reveals novel features of the molecular events occurring in the laticifers of Hevea brasiliensis (para rubber tree).

Latex of Hevea brasiliensis (Willd. ex A, Juss.) Mull. Arg. (Brazilian rubber tree) contains 30-50% (w/w) of natural rubber (cis-1,4-polyisoprene), which is an important raw material for many industrial uses. In order to gain insights into the molecular events occurring in latex, we analyzed more than 20,000 cDNA-AFLP-based TDFs (transcription-derived fragments) and 1176 ESTs. The results revealed several novel features of the latex transcriptome. First, the repertoire of the genes expressed in latex is unique. Only seven gene families accounted for more than 51% of the latex transcriptome. Among them, two of the most abundant ESTs were the genes encoding rubber particle proteins REF (rubber elongation factor) and SRPP (small rubber particle protein), comprising 29% of the total ESTs. Unexpectedly, several genes involved in the rubber biosynthesis were expressed at low levels in the latex. In fact, genes encoding cis -prenyltransferase (CPT), a potential candidate for rubber polymerase, were not present in the EST pool because of their low expression level. However, we were able to clone four full-length cDNAs by screening the same latex cDNA library used in the EST analysis and confirmed their enzyme activity in vitro. The second most abundant transcripts were defense- or stress-related genes, suggesting that defense is one of the functions of laticifers. Finally, the presence of the non-mevalonate DXP/MEP pathway for IPP synthesis in latex was noted by up-regulation of the 1-deoxy-D-xylulose 5-phosphate synthase gene.

サラワク州イバン村落の世帯にみられる生業選択

This paper examines livelihood diversity and flexibility in a village located near Miri, Sarawak, Malaysia. At present, a single typical livelihood of the Iban or an Iban village no longer exists, because the Iban easily adapted their livelihood in accordance with the local socio-economic changes. Even within a village, there are occupational options and periodic changes for each household. Studies on the Iban:zs livelihood have so far focused on the individual household (bilek farnily) unit This paper extends those analyses to stress the importance of the functions of household members, with respect to the conditions of labor, such as a number of household members capable of working and their ages and sex, character and work and activity preference, and individual skills. Individual members who have different characteristics and abilities contribute to a diverse and flexible way of livelihood characteristic of the Iban. In this study, it is found that the present livelihood and the periodic livelihood changes were brought about through the activities of individual members of households. Presently, in the village studied, various kinds of livelihood activities are practiced, including: planting wet paddy, pepper cultivation, rattan basketry, logging, and waged work outside the village. Preference for these activities by each household is different. Some households engage in all of the above-mentioned activities, while others only work for a wage. Waged work outside the village seems important, but some households make a living without it. Periodic changes in livelihood relate to changes in socio-economic conditions. Major changes occurred before the 19405 (the main activities were hill and wet paddy cultivation and wild rubber tapping), from the 1950s to the 1970s (main occupations were wet paddy cultivation and Para rubber tapping), and after the mid-l980s (various kinds of activities as mentioned above).

Some Rheological Properties of Latex from Parthenium argentatum Gray Compared with Latex from Hevea brasiliensis and Ficus elastica

Latex was purified from Parthenium argentatum Gray (guayule), Hevea brasiliensis Mull. Arg. (the Brazilian or para rubber tree), and Ficus elastica Roxb. (the Indian rubber tree) in ammonium alginate at pH 10. The rheological properties of the different latices (rubber particle suspensions) were determined and compared using flow temperature ramps. Latex from all three species became more viscous with increasing rubber particle concentration and decreasing temperature. At any particular temperature and concentration, latex from F. elastica was by far the most viscous, whereas the H. brasiliensis latex was the least viscous. In addition, the tendency for the latex to coagulate increased with increasing temperature and increasing particle concentration. F. elastica latex was highly sensitive to temperature, H. brasiliensis latex was the least sensitive, and P. argentatum latex demonstrated intermediate properties. The underlying causes of these differences in latex rheology are not clear but may partially relate to the particle size (largest in F. elastica and smallest in H. brasiliensis), the particle size distribution, and/or to the considerable differences in the biochemical components of the monolayer biomembrane that surrounds the various rubber particles. Differences in the molecular weight of the rubber contained within the rubber particles seem less likely to play a role because the particles remain intact in this study.

Measurement of lipase activity in rubber (Hevea brasiliensis) seed

AbstractLipase activity in para rubber (Hevea brasiliensis) seed was measured by monitoring the release of free fatty acid by lipolysis of the endogenous lipid in a crushed sample of seed incubated at 37.5°C for 30 min. Free fatty acid was determined colorimetrically by a modified copper soap method. Fresh seeds showed the highest lipase activity. Drying the seeds at 60°C inactivated the enzyme. Drying of the seed at this temperature may be useful as a pretreatment for extraction of oil from the seed.

Political versus techno‐economic factors in the development of non‐timber forest products: Lessons from a comparison of natural and cultivated rubbers in Southeast Asia (and South America)

An outstanding historic example of development of non‐timber forest products (NTFPs) involves the transition among the forest dwellers of Indonesia early this century, from gathering native forest rubbers to cultivating Para rubber fHevea brasilien‐sis), introduced from South America. The dynamics of this transition bring into question one of the key premises of current research on NTFPs, that the challenges to this development are largely technical and economic. Analysis of this transition and comparative data from South America suggest that the most important issue in NTFP development is not the size or efficiency of the return but rather who receives it. This analysis can contribute to a politically more informed analysis of the contemporary development of NTFPs and to improved understanding of relations between forest‐dwelling peoples and the broader societies in which they live.

Transition from native forest rubbers toHevea Brasiliensis (Euphorbiaceae) among tribal smallholders in Borneo

This is a study of the historic transition in Southeast Asia, in particular Borneo, from the exploitation of native forest rubbers to Para rubber (Hevea brasiliensis, Euphorbiaceae). During the second half of the nineteenth century, booming international markets subjected forest rubbers to more intensive and competitive exploitation. At the same time, the settlement patterns of tribal rubber gatherers were becoming more sedentary and their agriculture more intensive. Hevea spp. was better suited to these changed circumstances than the native forest rubbers, largely because it was cultivated not naturally grown. The status of Hevea spp. tn Southeast Asia as a cultigen, as opposed to a natural forest product, and the political-economic implications of this helps to explain the contrasting histories of smallholder rubber producers in the New and OM Worlds. This study offers an historical perspective on current debates regarding relations between forest resources, forest peoples, and the state.

Smallholder rubber and swidden agriculture in Borneo: A sustainable adaptation to the ecology and economy of the tropical forest

This is a study of the role of Para rubber cultivation in a system of swidden agriculture in Indonesian Borneo. Such smallholdings produce most of Indonesia’s rubber, which is the country’s largest agricultural generator of foreign exchange. Rubber integrates well into Bornean systems of swidden agriculture: the comparative ecology and economy of Para rubber and upland swidden rice result in minimal competition in the use of land and labor — and even in mutual enhancement — between the two systems. Rubber occupies a distinct niche in the farm economy: it meets the need for market goods, while the swiddens meet subsistence needs. The intensity of production on these smallholdings is, as a result, characteristically low (and may even vary inversely with market prices). This reflects the independence of these smallholders from external economic and political influences, which has been the key to their historical success. The special virtues of such “composite systems” merit greater attention by development planners.

A Revisionist View of Tropical Deforestation and Development

This study critiques one of the prevailing theories of tropical deforestation, namely that the forest is being cleared because its riches have been overlooked (the purported solution to which is the marketing of ‘rainforest crunch’). Edelman's work on the language of ‘helping’ is drawn on to suggest that a focus on the microeconomics of forest dwellers diverts attention from macro-economic and political issues whose impact on the forest is far more serious.The study begins with a parable from Kalimantan, relating how the discovery of a big diamond can bring misfortune to a poor miner. It is suggested that this parable applies more generally to resource development in tropical forests, and that the major challenge is not to give more development opportunities to forest peoples but to take fewer away.This principal is illustrated with respect to gold mining, rattan gathering, and truck-farming, in Indonesia. In each case, when a forest resource acquires greater value in the broader society, it is appropriated by external entrepreneurs at the expense of local communities. A detailed case-study is presented of the development of Para Rubber cultivation. Smallholders currently dominate this cultivation, despite steadfast opposition by both contemporary and colonial governments, whose self-interests are better served by the cultivation of the Rubber on large estates.Each of these cases illustrates the predisposition of political and economic forces in the broader society to take over successful resource development in the tropical forest. Contemporary efforts to develop ‘non-timber forest products’ are reinterpreted, in this light, as attempts to allocate to the forest dwellers the resources of least interest to the broader society. The absence of research in this area is attributed not to academic oversight but to conflicting political-economic interests.This thesis of resource exploitation is at variance with the ‘rain-forest crunch’ premise: namely that forest reserves are being overexploited by forest dwellers, that this is due to the absence of other sources of income, and that the solution is to help forest dwellers to find such sources. It is suggested that there has been no lack of such sources in the past, and that the problem has been in maintaining the forest peoples' control of them. The lesson of this analysis is not to ignore minor forest products, but to place them — and their potential development value for indigenous forest peoples — clearly within their proper political-economic context.Any resolution of the problems of tropical forest development and conservation must begin, not by searching for resources that forest dwellers do not already have, but byfirstsearching for the institutional forces which restrict the forest dwellers' ownership and productive use ofexistingresources. One of these institutional forces is discourse. It is widely understood that state elites seek to control valuable forest resources; it is less widely understood that an important means to this end is the control of resource-related discourse. De-mystification of the current debate over tropical deforestation and development is thus sorely needed.