Rubber Cultivation Research Articles

Carbon Stock Dynamics in Rubber Plantations Along an Elevational Gradient in Tropical China

Carbon (C) losses due to the conversion of natural forests adversely affect the biotic and abiotic components of terrestrial ecosystems. In tropical China, rubber cultivation often extends from its traditional range to elevations of up to 1400 m. However, C stock in rubber plantations along elevation gradients is poorly understood. In this study, we investigated biomass and C stock along elevation gradients in two age groups (8- and 12-year-old) of rubber monoculture plantations in Xishuangbanna, Southwest China. The C distribution across various tree sections, ranging from aboveground biomass (AGB) to belowground biomass (BGB), including litter, big dead branches, and different soil depths were measured. A significant negative correlation was observed between AGB, BGB, litter, and total ecosystem C stocks and elevation gradients in both age groups. However, no correlation was observed between the total soil C stock and elevation gradients in 8-year-old rubber plantations, while significant decline was detected in 12-year-old rubber plantations. The highest ecosystem C stock of 197.90 Mg C ha−1 was recorded at 900 m in 8-year-old plantations; whereas, in 12-year-old rubber plantations, the highest value of 183.12 Mg C ha−1 was found at 700 m. The total ecosystem C stock decreased to their lowest level at 1000 m in both the 8-year-old and 12-year-old plantations, ranging between 113.05 Mg C ha−1 and 125.75 Mg C ha−1, respectively. Moreover, total ecosystem C stock significantly decreased from 51.55% to 8.05% and from 42.96% to 11.46% between 700 m and 1100 m, in both 8-year-old and 12-year-old plantations, respectively. Regardless of elevation gradients, the total ecosystem C stock of 12-year-old rubber plantations was 1.98% greater than that of 8-year-old rubber plantations. Biomass was the second largest contributor, while soil accounted for 82% to 90%, and the other components contributed less than 2% of the total ecosystem C stock in both age groups. These fluctuations in C stock along elevation gradients in both 8- and 12-year-old plantations suggested that rubber growth, biomass, and C stock capacity decreased above 900 m, and that age and elevation are key factors for biomass and C stock in rubber monoculture plantations.

Integrated Assessment and Agricultural Planning in Selenium-Rich Hilly Soils: A Case Study on Land Use, Heavy Metal Contamination, and Nutrient Element Distribution

The strategic development of selenium-enriched soil cultivation is essential for effective agricultural land management. This research explores the sustainable utilization of selenium-rich soils in Qiongzhong County, Hainan Island. An extensive evaluation was conducted on 7266 surface soil samples, assessing the selenium concentrations, nutrient levels, heavy metals, pH values, and soil organic matter (SOM). In addition, analyses of 70 samples for organochlorine compounds and PAHs were performed. The results indicated average selenium content of 0.46 mg/kg, with 55.2% of the samples surpassing the selenium enrichment threshold of 0.4 mg/kg. According to the GB15618-2018 standards, 127 samples (1.75%) showed medium or high chromium-associated risks. No contamination from organochlorine compounds or PAHs was found, including the 16 priority-controlled PAHs with an average concentration of 30.3 µg/kg, confirming the soil’s high quality. The correlation and factor analysis identified surface enrichment as the main factor influencing selenium accumulation, presenting minimal environmental risks. Consequently, three categories of selenium-rich soil were defined: selenium-rich, pollution-free, and high-nutrient selenium-rich soil. Recommendations based on the soil characteristics and existing agricultural practices were made for the cultivation of selenium-rich vegetables, rubber, and nuts. This study lays a foundation for the sustainable management of selenium-rich soils, providing insights for further research and decision-making to optimize these resources, thus promoting environmental protection and agricultural sustainability.

Effect of dietary supplementation of rubber seed kernel pellet on feed utilization, rumen fermentation, fatty acid profiles and health status in swamp buffalo.

Rubber seed kernel is a by-product of rubber cultivation and are high in oil and protein. This study was conducted to evaluate the effect of supplementing rubber seed kernel pellet (RUSKEP) on feed intake, nutrient digestibility, rumen fermentation, rumen fatty acid profiles, blood parameters, and immune response in swamp buffalo. Four male swamp buffalo with an initial body weight (BW) of 254 ± 10 kg and 26 months of age were used in this research. The experimental design was a 4  4 Latin squared design with RUSKEP supplementation at 0, 4, 6, and 8% of dry matter intake (DMI). Animals were fed concentrate at 1.0% BW, while rice straw was fed ad libitum. Supplementation with RUSKEP did not change DMI or nutrient digestibility (p>0.05), while ether extract (EE) digestibility increased cubically with the addition of RUSKEP (p<0.01). The ruminal pH, ammonia-nitrogen (NH3-N), and the proportion of acetate (C2) were similar among treatments (p>0.05). The proportion of propionate (C3) increased linearly (p≤0.04), leading to a decrease in the acetate to propionate ratio (C2:C3) (p≤0.04) with the addition of RUSKEP. Furthermore, the butyrate (C4) proportion decreased linearly with RUSKEP supplementation (p=0.03). The addition of RUSKEP did not affect on linoleic acid (LA; C18:2 cis-9,12 + trans-9,12), or α-linolenic acid (ALA; C18:3 cis-9,12,15) (p>0.05). With RUSKEP supplementation, the stearic acid (C18:0) content increased quadratically (p<0.01). The increasing level of RUSKEP was higher in cholesterol and eosinophils (p≤0.03). The immune function (IgA, IgM, and IgG) was similar among treatments (p>0.05). Supplementing RUSKEP with up to 8% of DMI could improve rumen fermentation efficiency without affecting feed utilization, rumen PUFA profile, or immune response in swamp buffalo.

Patterns and Drivers of Greenhouse Gas Emissions in a Tropical Rubber Plantation from Hainan, Danzhou

The intensification of global climate change has made the study of greenhouse gas (GHG) emissions increasingly important. To gain a deeper understanding of the emission characteristics and driving factors of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) from rubber plantation soils, this study conducted a 16-month continuous observation in a rubber plantation in Danzhou, Hainan, employing the static chamber method for the monthly sampling and measurement of GHG emissions while analyzing the soil’s physical and chemical properties. The results indicated that the N2O flux exhibited no significant diurnal variation between the dry and rainy seasons, with an average emission rate of 0.03 ± 0.002 mg·m−2·h−1. A clear seasonal trend was observed, with higher emissions in summer than in winter, resulting in an annual flux of 3 kg·hm−2·a−1 (equivalent to 1.9 kg N·hm−2·a−1). N2O emissions were significantly correlated with soil temperature and moisture, explaining 46% and 40% of the variations, respectively, while soil ammonium nitrogen content also significantly influenced N2O and CO2 emissions. The rubber plantation soil acted as a source of N2O and CO2 emissions and a sink for CH2, with lower emissions of N2O and CO2 during the daytime compared to nighttime, and higher CH4 uptake during the daytime. In the dry season, there was a significant positive correlation between N2O and CO2 emissions (R2 = 0.74, p &lt; 0.001). This study reveals the diurnal and seasonal patterns of GHG emissions from rubber plantation soils in Hainan and their interrelationships, providing a scientific basis for the low-carbon management of rubber plantations and GHG mitigation strategies, thereby contributing to attempts to reduce the impact of rubber cultivation on climate change.

Enhanced Rubber Yield Prediction in High-Density Plantation Areas Using a GIS and Machine Learning-Based Forest Classification and Regression Model

Rubber is a perennial plant grown for natural rubber production, which is used in various global products. Ensuring the sustainability of rubber cultivation is crucial for smallholder farmers and economic development. Accurately predicting rubber yields is necessary to maintain price stability. Remote sensing technology is a valuable tool for collecting spatial data on a large scale. However, for smaller plots of land owned by smallholder farmers, it is necessary to process productivity estimates from high-resolution satellite data that are accurate and reliable. This study examines the impact of spatial factors on rubber yield and evaluates the technical suitability of using grouping analysis with the forest classification and regression (FCR) method. We developed a high-density variable using spatial data from rubber plots in close proximity to each other. Our approach incorporates eight environmental variables (proximity to streamlines, proximity to main river, soil drainage, slope, aspect, NDWI, NDVI, and precipitation) using an FCR model and GIS. We obtained a dataset of 1951 rubber yield locations, which we split into a training set (60%) for model development and a validation set (40%) for assessment using area under the curve (AUC) analysis. The results of the alternative FCR models indicate that Model 1 performs the best. It achieved the lowest root mean square error (RMSE) value of 19.15 kg/ha, the highest R-squared (R2) value (FCR) of 0.787, and also the highest R2 (OLS) value of 0.642. The AUC scores for Model 1, Model 2, and Model 3 were 0.792, 0.764, and 0.732, respectively. Overall, Model 4 exhibited the highest performance according to the AUC scores, while Model 3 performed the poorest with the lowest AUC score. Based on these findings, it can be concluded that Model 1 is the most effective in predicting FCR compared to the other alternative models.

Response of N, P, and metal ions in deep soil layers to long-term cultivation of rubber and rubber-based agroforestry systems

The growing demand for natural rubber products has driven the expansion of rubber plantations in recent decades. While much attention has been given to studying the long-term effects of rubber and rubber-based agroforestry systems on surface soil properties, there has been a tendency to overlook changes in soil properties in deeper layers. Our study addresses this gap by examining alterations in nitrogen (N), phosphorus (P), and metal ion levels in deep soil layers resulting from the prolonged cultivation of rubber and rubber-based agroforestry systems. We found notable shifts in soil NH4+ and NO3− concentrations within the 0–30 cm soil layer across different-aged rubber and rubber-based agroforestry systems. Particularly in mature systems, NO3− and available P levels were close to zero below 30 cm soil depth. Introducing Flemingia macrophylla into young rubber plantations increased soil NH4+ and NO3− in the 0–90 cm soil layer and available P in the 0–10 cm soil layer. Over the long term, cultivation of rubber plantations increased the depletion of total P in the 0–50 cm soil layer, available iron (Fe) and manganese (Mn) in the 30–90 cm soil layer, available copper (Cu) and zinc (Zn) in the 0–90 cm soil layer, accompanied by a decrease in soil pH and increase in exchangeable aluminum (Al) in the 0–90 cm soil layer. Notably, soil exchangeable Al levels exceeding 2.0 cmol kg−1 appeared to induce aluminum toxicity. Furthermore, soil pH below 5.2 triggered a sharp release of exchangeable Al within the 0–90 cm soil layer of rubber plantations, with soil available P nearing zero when exchangeable Al levels assed 7.3 cmol kg−1. Our findings underscore the profound impact of long-term rubber plantation cultivation on surface and deep soil properties. Addressing soil degradation in these deep soil layers poses significant challenges for future soil restoration efforts.

Exhaustive identification and characterization of Colletotrichum siamense and Colletotrichum fructicola as causative agents of circular leaf spot disease of rubber tree (Hevea brasiliensis) in India

The rubber tree (Hevea brasiliensis) is one of the major domesticated crops planted commercially for the production of natural rubber (NR) worldwide. In recent years, rubber trees in the Southern states of India and other rubber-producing countries have experienced a severe leaf spot disease, characterized by the appearance of several brown circular spots in the initial stage, which later spread all over the lamina of fully matured leaves, leading to yellowing and defoliation. The causal organism of this Circular Leaf Spot (CLS) disease has not been conclusively identified in any previous studies. In this study, we collected infected leaf samples from various locations in the South Indian states. We aimed to identify the actual fungal pathogen that causes the CLS disease on rubber trees. Based on the morphological and molecular analysis of the most frequently isolated fungi from infected leaf samples were identified as Colletotrichum siamense and Colletotrichum fructicola. Pathogenicity tests also confirmed the involvement of isolated Colletotrichum spp. in the development of CLS disease. These findings provide valuable insights into understanding the CLS disease and its impact on rubber cultivation. To our knowledge, it is the first report of C. siamense and C. fructicola associated with CLS disease of rubber trees in India.

Agricultural land use policies and landscape dynamics: Evidence from rainforest agroecological zone

Agricultural-land use policies play a crucial role in shaping agroecological landscapes globally. The evidence suggests that some of these policies tend to have undesired feedback/trade-offs, particularly about coastal resource use and conservation planning. The present study explores how agricultural policies influence land use/land cover (LULC) transition patterns in Ghana's Rain Forest Agroecological Zone (RFAZ). Landsat satellite images for 1991, 2008, and 2022 were acquired for the LULC mapping. Change detection and Intensity analysis were used to assess the pattern of land change. Also, documentary research processes were used to review and assess agricultural land use policies. The results showed that before rubber-related policy implementation, oil palm plantation was the dominant LULC type in the 1990 s. In the 1990 s and early 2000 s, there was a conscious government drive to leverage oil palm plantation development. This led to the growth in the size of oil palm plantations within the RFAZ landscape, considering the zone’s conducive natural environment. However, between 2008 and 2022, corresponding to the period of the increased promotion of rubber cultivation through the Outgrower project in the RFAZ, rubber plantations became the predominant land use, with an area of 11,763.81 ha in 2008 and 21,611.61 ha in 2022. The results from the LULC mapping and the intensity analysis showed that the Rubber Outgrowers Plantation Project (ROPP) and Norpalm Smallholder Scheme Project (NSSP) have degraded the natural cover through rubber and oil palm cultivation. The authors conclude that landscape dynamics, particularly in rainforest agroecological zones, represent a nexus challenge transforming policy adaptation's discursive context. The study recommends that agriculture and landscape policy/projects must have/take intermediary steps to address the feedback/trade-offs from well-intended initiatives. The study further suggests that management plans and strategies in the RFAZ should be consistent with the strict protection of forest reserves and water bodies.

Meteorological Impacts on Rubber Tree Powdery Mildew and Projections of Its Future Spatiotemporal Pattern

Meteorological conditions play a crucial role in driving outbreaks of rubber tree powdery mildew (RTPM). As the climate warms and techniques improve, rubber cultivation is expanding to higher latitudes, and the changing climate increases the RTPM risk. Rubber plantations on Hainan Island, situated on the northern margin of the tropics, have been selected as a case study to explore the meteorological mechanisms behind RTPM outbreaks quantitatively using a structural equation model, and project current and future RTPM outbreak patterns under different climate change scenarios by building predictive models based on data-driven algorithms. The following results were obtained: (1) days with an average temperature above 20 °C and days with light rain were identified as key meteorological drivers of RTPM using structural equation modeling (R2 = 0.63); (2) the Bayesian-optimized least-squares boosted trees ensemble model accurately predicted the interannual variability in the historical RTPM disease index (R2 = 0.79); (3) currently, due to the increased area of rubber plantations in the central region of Hainan, there is a higher risk of RTPM; and (4) under future climate scenarios, RTPM shows a decreasing trend (at a moderate level), with oscillating and sporadic outbreaks primarily observed in the central and northwest regions. We attribute this to the projected warming and drying trends that are unfavorable for RTPM. Our study is expected to enhance the understanding of the impact of climate change on RTPM, provide a prediction tool, and underscore the significance of the climate-aware production and management of rubber.

Spatial variation of soil organic carbon under major rubber planting regions in China

AbstractUnderstanding the dynamic relationships between soil organic carbon (SOC) and stand age are essential to quantify and predict the terrestrial carbon sequestration potential. However, the spatial patterns in the response of rubber plantation SOC to stand age and their driving factors remain unclear. Based on SOC and its components measurement at different soil depths (0–40 cm) in rubber plantations under five different age classes (0–5, 5–10, 10–20, 20–30, and &gt;30 years) in three major rubber cultivation regions in China, distribution pattern and controlling factors of SOC were investigated. We found that SOC and its components showed significant spatial variability vertically with soil depth and laterally across sampling sites. SOC contents in three major rubber cultivation regions range from 4.48 to 20.13 g kg−1 at a depth of 0–40 cm. Among the sampling sites, Jinghong had the highest SOC content at a depth of 0–10 cm (20.13 g kg−1). On a large‐scale, the relationship between SOC and stand age in rubber plantations did not show a consistent pattern among different sampling sites. Additionally, annual rainfall, soil moisture content, and soil pH had a stronger impact on SOC in rubber plantations compared to stand age. The results indicated that the spatial variability of SOC in rubber plantations with stand age could be influenced by specific soil properties and climate‐related variables at each sampling site. This study emphasized the significance of conducting multi‐site, multi‐scale studies to enhance our understanding of SOC dynamics and its influencing factors, and help to more accurately predict the dynamic changes of soil carbon storage in rubber plantations.

The large-scale expansion of rubber plantations in southern India: major impacts and the changing nature of drivers

This study investigates the major environmental and socio-economic impacts of an increase in the area of rubber plantations and the changing patterns of drivers of land use changes. Using a combination of geospatial techniques and socio-economic methods, we mainly analyzed the rate of increase in area under rubber plantations, the major impacts of land use changes, and the changing drivers of land use changes. Our results show that the area under rubber plantations has increased significantly within the study area, with the area under rubber plantations increasing from 30 to 74% of the total area within five decades. Impact assessment of land use changes based on household surveys showed significant improvement in the socio-economic conditions of the farmers, however, at the expense of severe environmental degradation. Our results also indicate that while areas under rubber plantations continue to increase, the drivers of land use changes have changed over time. Furthermore, it has been observed that in the past, many interventions prioritized social and economic development and placed less emphasis on the ecological stability of the region. Perceptions of farmers revealed that the effects of ecological fragility already affected the economic robustness of the whole area. Therefore, we conclude that government interventions to support additional rubber cultivation should also focus on ecosystem stabilization in order to minimize the risk of an ecological catastrophe that would significantly affect the economic prosperity of the region.

Rubber plantation size and global rubber price are linked to forest loss and degradation in Jambi, Sumatra

AbstractNatural rubber cultivation is one of the main drivers of tropical deforestation and biodiversity loss. This study examines regulatory and socio‐economic conditions that increase the susceptibility of rubber plantations to deforestation and degradation, aiming to support zero‐deforestation pledges and sustainability commitments made by the natural rubber industry. By combining bottom‐up socio‐economic survey data from rubber smallholder farmers in Indonesia with top‐down spatial datasets on forest loss and degradation, this study identifies factors associated with deforestation, tree cover loss, and degradation of high‐risk plantations. In Jambi Province, Indonesia, from 1991 to 2018, the overall tree cover loss in areas adjacent to rubber plantations was positively correlated to plantation size, remoteness (travel time to cities), and distance to the nearest protected areas, indicating that larger, remotely located plantations likely expanded more into forests between 2000 and 2018. Similarly, tropical forest degradation was positively associated with plantation size, travel time to cities, and distance to protected areas. A higher rubber price in the preceding year correlated with increased annual deforestation and forest degradation, whereas lower prices had the opposite effect. These results suggest that monitoring price changes and identifying plantations that are near non‐protected forest frontiers could enable early detection and potential mitigation of deforestation threats.

Faunal Diversity and the Ecological Aspects of a Community-Based Fragmented Lowland Rainforest Patch in Western Province, Sri Lanka

Wawekale Rainforest Reserve (WRR) is a primary lowland tropical rainforest area in the Western Province of Sri Lanka, established with diversity, but disturbed by human activities such as rubber cultivation, logging, poaching, chemical release, and the collection of firewood. Visual Encounter Surveys (VES) were conducted for 100 hours in the year 2022, which covered wide habitat distribution. The herpetofaunal diversity was measured in the WRR which can indicate broader ecological shifts, environmental changes, or habitat degradation. Water quality was measured in the WRR area to determine the ecosystem health and human impact. The study reports 171 species in 73 families, including two Critically Endangered (1.17%), six Endangered (3.51%), 16 Vulnerable (9.36%), and 14 Near Threatened (8.19%) species according to the IUCN Red List. The study area showed 51 endemic faunal species in Sri Lanka, which represented 29.83% of endemism. Based on the observations conducted on the herpetofauna diversity, the Shannon-Wiener diversity index (H) was calculated and the overall herpetofauna (H’H) showed high diversity within the forest premises. The water quality of the forest fragment had an influence from anthropogenic activities such as removing forest cover, bathing, washing vehicles, and releasing agro-chemical compounds resulting in high water temperature, basic pH level, high electrical conductivity, and high total dissolved solid conditions. The WRR, designated under protection, exhibits the need for immediate remedial actions to mitigate human-induced pollution and deforestation, emphasizing the critical importance of implementing proactive conservation measures to sustain ecological integrity and preserve biodiversity.

Efisiensi Alokatif Budidaya Karet di Kecamatan Sungai Ambawang Kabupaten Kuburaya

This study aims to analyze the factors that influence rubber production and to analyze the efficiency of the price of rubber production. The variables examined in this study include the efficiency of the use of rubber production factors, the Cobb-Dounglas production function is unsed, Classic Assumption Test, Statistical Test and Allocative Efficiency. The test results on the production factors show that the variable area of land.Labor, fungicide had a significant effect on production. NPK fertilizer and length of farming had no significant effect on rubber production. The results of the allocative efficiency analysis showed that the use of land area, labor and fungicides was inefficient in rubber cultivation in Ambawang district, Kubu Raya Regency.

Isu dan Impak Perkembangan Penanaman Getah di Perak, 1958-1984

This research is to see to what extent the development of commercial plantations, in particular rubber plants in Perak between 1958 and 1984 has had a positive impact on the socioeconomic progress of the population in this state. The elemental of this rubber plant development is seen through the development of this plant in the state of Perak, the challenges faced by the people in rubber cultivation activities, especially in facing the problem of South American Leaf Blight (SALB) disease and how they resolved it during the period studied. This research adopted historical qualitative method on sources and materials obtained from the National Archives of Malaysia Kuala Lumpur, National Archives of Malaysia Perak State Branch, Hamzah Sendut Library 1, Universiti Sains Malaysia in the Malaysiana and Archives section, Kuala Kangsar Public Library, Perak, and the library at the National Archives of Malaysia Perak State Branch.This study has found that the rapid development of rubber plantations in Perak has left a significant impact on socioeconomic aspects among residents in the state of Perak. For example, the rate for employment opportunities and generated income had increased especially for women, as well as there were improvements in infrastructure, education, and health. This matter shows that the progressiveness of the economic sector in Perak is not solely contributed by tin mining activities as widely discussed by previous studies. It turns out that economic activities based on rubber cultivation have also had a positive impact on the progress of the lives of residents in the state of Perak.

Isu dan Impak Perkembangan Penanaman Getah di Perak, 1958-1984

This research is to see to what extent the development of commercial plantations, in particular rubber plants in Perak between 1958 and 1984 has had a positive impact on the socioeconomic progress of the population in this state. The elemental of this rubber plant development is seen through the development of this plant in the state of Perak, the challenges faced by the people in rubber cultivation activities, especially in facing the problem of South American Leaf Blight (SALB) disease and how they resolved it during the period studied. This research adopted historical qualitative method on sources and materials obtained from the National Archives of Malaysia Kuala Lumpur, National Archives of Malaysia Perak State Branch, Hamzah Sendut Library 1, Universiti Sains Malaysia in the Malaysiana and Archives section, Kuala Kangsar Public Library, Perak, and the library at the National Archives of Malaysia Perak State Branch.This study has found that the rapid development of rubber plantations in Perak has left a significant impact on socioeconomic aspects among residents in the state of Perak. For example, the rate for employment opportunities and generated income had increased especially for women, as well as there were improvements in infrastructure, education, and health. This matter shows that the progressiveness of the economic sector in Perak is not solely contributed by tin mining activities as widely discussed by previous studies. It turns out that economic activities based on rubber cultivation have also had a positive impact on the progress of the lives of residents in the state of Perak.

Soil Acidification Vulnerability and Long-term Trace Metal Depletion Under Rubber Tree Plantations in the Semi-mountainous Region of West Côte d'Ivoire

The objective of this study was to assess the impacts of rubber cultivation on soil properties in the Tonkpi region, western Côte d’Ivoire. The study proceeded by comparing soils under rubber tree cultivation of different ages to those under other crops or fallow. The soils were sampled from a depth of 0 to 25 cm. The samples were dried and then sent to the central laboratory of the University of Man for physical and chemical analyses. Soil pH was measured with the multiparameter HANNA HI9829. Soil potentially toxic elements like As, Zn, Cu, Ni, Co, Cr, Mo, Fe, Se, Ca, Pb, K, Mn and V were analyzed, at the geological laboratory of the University Felix Houphouet-Boigny with a handheld NITON XL3t X-ray fluorescence analyzer. The results showed that soils from rubber-cultivated areas had a sandy loamy-clay texture, while those from the control area had a sandy-loamy texture. The soil pH was strongly to slightly acidic, with pH varying from 4.86 to 6.34, while the bulk densities varied from 0.51/g cm3 to 0.62 g/cm3. The redox potential of the soils was inferior to 400 mV (Eh ˂ 400 mV). This study also revealed a general decrease in the potentially toxic element content of soils under rubber cultivation. The soil contents of Cr, Co and Cu were inferior to the limit of detection. The Pb, Mn and Ca concentrations were 4.81, 194.2 and 2140 µg g-1, respectively, and these were significantly different from those of the other soils. This study provided a major insight into the effect of rubber cultivation in western Côte d'Ivoire.

Yield Performance of Intercropped Marantha arundinacea L. (Arrowroot) in Two Rubber Plantation Designs

Developing rubber agroforestry systems is crucial to ensure the sustainable development of natural rubber cultivation. This study focuses on the starch crop Maranta arundinacea (arrowroot) and assesses its productivity and influencing factors when intercropped in 6–7-year-old conventional single-row and double-row rubber plantations. We analyze various aspects, including light resources, root distribution, soil nutrients, arrowroot growth characteristics, and product quality. The results indicate that the daily average photosynthetically active radiation (PAR) in the double-row rubber agroforestry system intercropping area ranges from 896.4 to 940.2 μmol·m−2·s−1. Additionally, the rubber tree roots near the intercropping area are less dense (107.0 g cm−3). In contrast, the conventional single-row rubber agroforestry system has a significantly lower daily average PAR of only 145.7 μmol·m−2·s−1, and the nearby rubber tree roots are more abundant (616.2 g cm−3). Although soil nutrient levels were slightly lower in the intercropping area on the double-row treatment compared to the single-row treatment, there was no statistical difference (p &lt; 0.05). Arrowroot’s photosynthetic capacity in the double-row rubber agroforestry system intercropping area is significantly greater than in the single-row rubber agroforestry system intercropping area. The yield per unit area in the former (23.46–27.47 t·ha−1) is also significantly higher than in the latter (2.87–4.75 t·ha−1, p &lt; 0.05), with higher starch content. Therefore, arrowroot exhibits higher productivity when intercropped in double-row rubber agroforestry systems, making it suitable for establishing a “rubber–arrowroot” agroforestry model to enhance the yield per unit area of rubber plantations.

EVALUATION OF THE BEHAVIOR OF RUBBER TEAS IN THE MARGINAL ZONE OF COTE DIVOIRE: CASE OF THE LOCALITIES OF MAN, TOUMODI AND PRIKRO

For a better orientation of Ivorian rubber cultivation in new areas of occupation, a study with the main objective of evaluating the behavior of rubber trees, with a view to better orientation of the extension of this culture was undertaken in the localities of Man, Toumodi and Prikro. The plant material used was rubber tree clones. During this study, the methodology consisted of evaluatingthe evolution of trees at 1.7m from the ground for mature plants and 1m from the ground for immature plants by measuring the circumference of the trees planted with a tape measure on different biotopes and soil textures previously defined. Production, dry notch rate and dry notch length of mature trees was also measured on the same parameters of the previous crop and texture. The results revealed thatthe previous cultivation of the rubber plots influences the mortality rate of the plants with a low rate observed in Man (17.30%) on the previous forest, also the trees had good growth on this previous one in Man (8.5cm.year-1) and Prikro (9cm.year-1). At ground level, the plants had a better level of radial growth in the localities of Man (8.30 and 9.06 cm.year-1) and Prikro (8.01 cm.year-1) with a more texture clayey (25% &lt; clay &lt; 50%). The average rubber production was also better in Man on the previous forest crop (63.85 ± 15.1 g.a-1s-1) similarly for the more clayey texture (25% &lt; clay &lt; 50%) with 63.27 ± 6 .1 g.a-1s-1. Rubber production from these new localities was generally good. So, through the results of this investigation, it should be noted that new rubber growing areas could be an asset for rubber production in Côte dIvoire. As a result, this culture can be encouraged in these areas, but with monitoring and supervision of producers on good agricultural practices.

Growth, Structural Change and Plantation Crops: A Brief History of Rubber Cultivation in Travancore

Plantation crops are commodities worthy of serious attention because of the central and longstanding place it has held in the world economy and in the lives of millions of people. The introduction of it marked a distinct departure from the peasant agriculture of Travancore. Large scale mono-culture of these crops for the export market introduced certain new features of structure and pattern. In this chapter a product-oriented approach has been chosen and attention has been focused on a limited number of crops (Coffee, Tea, Rubber) which account for a major share in the plantation economy .One of the few holdovers from the era of the spice trade and colonialism, these crops had been a major traded commodity since the second half of the nineteenth century. Colonial plantations in Travancore had three phases. The first period started in the 1850s, and the first plantation crop was coffee. During the first thirty years after the planting of coffee, the principal form of ownership was proprietary. From the eighties, the ownership structure began to change and partnership firms became common. The main plantation crop of this period was Tea. The rise of rubber cultivation in 1900 introduced changes in the structure of ownership. Before going to the details it would be apt to discuss about the cultivation of these particular crops.