Rubber Plantations Research Articles

Anthropogenic restoration exhibits more complex and stable microbial co-occurrence patterns than natural restoration in rubber plantations

Forest restoration is an effective method for restoring degraded soil ecosystems (e.g., converting primary tropical forests into rubber monoculture plantations; RM). The effects of forest restoration on microbial community diversity and composition have been extensively studied. However, how rubber plantation-based forest restoration reshapes soil microbial communities, networks, and inner assembly mechanisms remains unclear. Here, we explored the effects of jungle rubber mixed (JRM; secondary succession and natural restoration of RM) plantation and introduction of rainforest species (AR; anthropogenic restoration established by mimicking the understory and overstory tree species of native rainforests) to RM stands on soil physico-chemical properties and microbial communities. We found that converting tropical rainforest (RF) to RM decreased soil fertility and simplified microbial composition and co-occurrence patterns, whereas the conversion of RM to JRM and AR exhibited opposite results. These changes were significantly correlated with pH, soil moisture content (SMC), and soil nutrients, suggesting that vegetation restoration can provide a favorable soil microenvironment that promotes the development of soil microorganisms. The complexity and stability of the bacterial-fungal cross-kingdom, bacterial, and fungal networks increased with JRM and AR. Bacterial community assembly was primarily governed by stochastic (78.79 %) and deterministic (59.09 %) processes in JRM and AR, respectively, whereas stochastic processes (limited dispersion) predominantly shaped fungal assembly across all forest stands. AR has more significant benefits than JRM, such as a relatively slower and natural vegetation succession with more nutritive soil conditions, microbial diversity, and complex and stable microbial networks. These results highlight the importance of sustainable forest management to restore soil biodiversity and ecosystem functions after extensive soil degradation and suggest that anthropogenic restoration can more effectively improve soil quality and microbial communities than natural restoration in degraded rubber plantations.

Sustainable integration of rubber plantations within agroforestry systems in China: current research and future directions

The integration of rubber plantations with agroforestry systems, or the under-forest economy, represents a pivotal shift towards sustainable agriculture in China. This paper reviews the latest research on agroforestry practices and innovations within China's rubber plantation under-forest economy, with a focus on the balance between economic productivity and environmental sustainability. We explore the adoption of diverse agroforestry models that incorporate rubber trees with other valuable plant species, aiming to enhance ecosystem services, biodiversity, and farmers' livelihoods. The review highlights significant advancements in sustainable management practices, including species selection, planting designs, and soil and water conservation techniques that contribute to the resilience of these systems against environmental stresses. Economic analyses underscore the potential for rubber agroforestry systems to improve income diversification and stability for rural communities while also navigating market challenges. Environmental assessments reveal the positive impacts of these practices on carbon sequestration, biodiversity preservation, and soil health, positioning rubber agroforestry as a beneficial strategy for mitigating climate change effects. However, the review also identifies challenges, including the need for supportive policy frameworks, access to knowledge and technology for smallholders, and further research on long-term sustainability outcomes. Future directions for research are proposed, emphasizing the integration of ecological, economic, and social dimensions to fully realize the potential of the rubber under-forest economy in China.

Adaptation of Latex Diagnosis Parameters Determination using Multiplate Reader and Freeze-Drying Conservation to Support Large-Scale Utilization in Rubber Plantations

Adaptation of Latex Diagnosis Parameters Determination using Multiplate Reader and Freeze-Drying Conservation to Support Large-Scale Utilization in Rubber Plantations

Integrative cultivation pattern, distribution, yield and potential benefit of rubber based agroforestry system in China

Rubber trees are the most widely cultivated natural rubber crops globally. Although commercial cultivation of rubber trees occurs in Hainan, Yunnan and Guangdong provinces in the tropical regions of southern China, adapting rubber plantations to global sustainable development remains a challenge. Particularly within rubber plantations, sustainability and efficiency in production and managements often suffer due to soil degradation resulting from monoculture land use and poor management practices. Rubber based agroforestry systems offer a sustainable approach to mimic natural ecosystem. This study aims to explore the patterns, distribution, yields and potential benefits of rubber agroforestry system. The results show that there were 15 types of rubber agroforestry patterns, including Rubber–Banana, Rubber–Pineapple, Rubber–Cassava, Rubber–Passionfruit, Rubber–Flower plants, Rubber–Ficus hirta, Rubber–Corn, Rubber–Edible fungus, Rubber–Alpinia oxyphylla, Rubber–coffee, Rubber–Phrynium hainanense, Rubber–Amomum villosum, Rubber–Amorphophallus, Rubber–Tea, Rubber–Pandanus amaryllifolius. These patterns are distributed across 17 counties in Hainan Province and 10 counties in Yunnan Province. The total area of rubber based agroforestry exceeds 79,520 ha, comprising 35,998 ha of young rubber agroforestry systems and 43,522 ha of mature ones. The total annual output value benefit of rubber agroforestry systems surpasses 834 million US dollars. Young agroforestry systems yield an annual output value of 269 million US dollars, while mature agroforestry systems contribute 110 billion US dollars from dry rubber and 455 million US dollars from integrative crops. Yunnan Province's economic output value for rubber agroforestry systems exceeds that of Hainan Province due to higher output values of passionfruit from young rubber plantations and Amorphophallus from mature ones. These results indicate the widespread acceptance of rubber agroforestry systems in China's rubber planting practices and their significant potential for output benefits. As environmentally friendly and sustainable production patterns, rubber agroforestry systems have the potential to enhance the sustainable livelihood capacity of smallholders and contribute to poverty alleviation efforts in China and globally. These findings enrich agroforestry systems science and provide valuable insights for optimizing industrial policies and technology transfer.

Utilizing rubber plant leaf petioles derived activated carbon for high-performance supercapacitor electrodes

This research introduces a novel and sustainable method that exploits the untapped potential of waste biomass, specifically converting dead leaf petioles from Ficus elastica, an industrial crop commonly known as rubber plants, into high-performance activated carbon (AC) for supercapacitor electrodes through a straightforward pyrolysis process. The prepared AC is used as an electrode substance to construct symmetrical supercapacitors. It underwent detailed morphological and structural analyses through various analytical instruments to assess the AC's performance and quality. Electrochemical assessments using a two-electrode configuration with 1 M KOH as the electrolyte revealed that the AC electrodes display exemplary characteristics of electric double-layer capacitance. This conclusion was drawn from observing cyclic voltammetry curves that were rectangular and symmetrical across scan rates ranging from 10 to 100 mV/s. Remarkably, at a scan rate of 10 mV/s, these AC electrodes achieved a specific capacitance of 128 F/g. The superior performance of the AC, when compared to other biomass-derived electrode materials, can be attributed to its extensive surface area and significant porosity. Moreover, electrodes crafted from AC derived from rubber plants showed remarkable durability over 10000 charge-discharge cycles, maintaining 89 % of their original capacitance and achieving a Coulombic efficiency of up to 87 %. During prolonged discharge periods, these electrodes exhibited a high specific capacitance, which contributed to achieving a power density of 200 W/kg and an energy density of 11.4 Wh/kg. This study highlights the viability of rubber plant waste in advanced energy storage systems and significantly contributes to sustainable material science. By offering an eco-friendly approach for supercapacitor electrode fabrication, this research aligns with global efforts towards sustainable energy storage technologies, demonstrating the practicality of environmentally benign materials in high-performance applications.

Sosialisasi Pengetahuan Jamur Akar Putih pada Tanaman Karet kepada Masyarakat Petani Karet di Banyuasin III, Sumatera Selatan

White root disease is a major disease threatening the productivity of rubber plants. The community’s knowledge about White root disease is still limited, especially in recognizing early symptoms and its impact on rubber plants. Therefore, this community service activity aims to socialize knowledge about White root disease to the rubber plantation community in Banyuasin III, South Sumatra. This activity involves a series of counseling and interactive discussions about White root disease, including the introduction of symptoms, impacts on plants and the environment, and the importance of early detection. In addition, this activity also involves field demonstrations on how to identify White root disease symptoms in rubber plants. The results of this activity show an increase in community knowledge and awareness about White root disease. The community has become more capable of recognizing the early symptoms of White root disease and understanding the importance of early detection to prevent further spread. This activity contributes positively to the efforts of sustainable rubber plant management in Banyuasin III, South Sumatra.

Assessing Borneo’s tropical forests and plantations: a multi-sensor remote sensing and geospatial MCDA approach to environmental sustainability

The assessment of environmental sustainability is of utmost importance for the forests and plantations in Borneo, given the critical need for environmental protection through the identification and mitigation of potential risks. This study was conducted to assess the environmental sustainability of tropical forest and plantations landscape, a case study in northern Sabah, Malaysian Borneo. Applications of the latest high-resolution multi-sensor remote sensing and geospatial MCDA are cost-effective and useful for large-scale environmental sustainability assessment. The land use land cover (LULC) of the study area was mapped with synergistic use of Sentinel-1 Synthetic Aperture Radar (SAR) and Sentinel-2 optical and high-resolution PlanetScope satellite imageries, resulting in overall accuracy of 87.24%. Five sustainability indicator layers: slope erosion protection, river buffer, landscape connectivity and quality, high conservation value (HCV), and water turbidity were developed from the LULC map, ancillary datasets of SRTM, and forest operation basemap with reference to standards from the Environment Protection Department (EPD), Roundtable on Sustainable Palm Oil (RSPO), and Forest Management Plan (FMP) for the analysis using multi-criteria decision analysis (MCDA) model. The results revealed that overall, the study areas are in the high sustainability category at 61%, medium at 31%, and low at only 8%. We analyzed the environmental sustainability of five land use boundaries, and the results showed that Industrial Tree Plantations (ITP) and Village Reserve are mostly in the high category. Meanwhile, oil palm plantations, rubber plantations, and forest reserve (FR) are the majority in the medium category. Both oil palm and rubber plantations are a majority in the medium class due to monocropping land use type having low landscape connectivity and quality individual sustainability indicator layer. The study presented the concept of use of multi-sensor remote sensing for LULC mapping with geospatial MCDA for environmental sustainability assessment useful to stakeholders for improving the management plan also contributing toward the progress of achieving UNSDGs and addressing REDD+.

Budidaya Tanaman Karet untuk Perekonomian yang Lebih Positif

Rubber plants are a type of medicinal plant that has many health benefits, including treating small wounds, as a medical device, preventing stomach acid, for clothing, treating body aches, and as a fever-reducing medicine. The purpose of this community service is to provide information on how to increase the potential of natural resources located in Lebak, which is an area that has quite high potential in the rubber plantation business in general, but currently it has not been utilized optimally by the local community at this time. Most of the rubber plants that are produced are sold individually without knowing the harvest that the accounting information system consumes. This is due to a lack of innovation from the local community. Therefore, cultivating rubber plants is one way that can be done by harvesting quite small or large areas of land that can be put to good use, maintaining nutritional value and increasing economic value. With this cultivation empowerment, it is hoped that it can help improve the economy of the Lebak community and take advantage of the harvest of rubber plants for social welfare which is more durable to give rise to various innovations in processing rubber itself in a sustainable manner.

Characteristics of antioxidant activity of functional drinks from kebo rubber leaf extract and lemongrass extract

Abstract The rubber plant (Ficus Elastica L.) is an ornamental plant that is rarely used for consumption. This research aims to determine the characteristics of the antioxidant activity of functional drinks from rubber leaf extract and lemongrass extract. The research method used the Randomized Complete Block with two factors i.e., the ratio of rubber leaf extract and lemongrass extract (70%:30% w/w; 50%:50% w/w; 30%:70% w/w), and the ratio of stevia solution and sugar solution (0:100%; 50%:50%; 100%:0), that had 2 repetitions and resulted in 18 samples of experimental. Then the results were tested its antioxidant activities using the DPPH method and tannin analysis. The best result for antioxidant activity was obtained by the H1T3 sample with an IC50 value is 12.41 ppm, flavonoid content is 10.99% and tannin content is 2.86%. From the parameter results, the functional drinks of rubber leaf extract and lemongrass extract have the potential to contain a very strong antioxidant activity.

Effects of Conversion of Rubber to Oil Palm Plantations on Soil Properties and Hydrological Dynamics in the Low Country Wet Zone of Sri Lanka

A study was conducted to investigate the impacts of converting rubber plantations into oil palm plantations on soil properties and soil hydrology. Soil organic carbon (SOC), bulk density (BD), aggregate stability (AS), saturated hydraulic conductivity (Ks), soil water retention, texture, thermal properties, and pH were determined using soil samples collected from different depths of a twelve-year-old oil palm and rubber cultivated fields located in low country wet zone of Sri Lanka. In each field, volumetric water content (VWC) of soil was continuously measured at four soil depths (0-25, 25-50, 50-75, and 75-100 cm) over a seven-month period. While the study revealed a 40% lower SOC in 0-25 cm soil layer of the oil palm field compared to the rubber field, no significant changes were observed in BD, porosity, pore size distribution, AS, and Ks for the two fields. However, the volumetric heat capacity of rubber grown soil was significantly higher than that of the oil palm grown soil. Oil palm utilized the most water from 25-75 cm soil layer; whereas, rubber extracted more water from deeper soil layers (75-100 cm). Soil water depletion in oil palm field was faster during dry periods than in rubber fields highlighting the need to examine the soil water extraction patterns of oil palm during extended dry spells in future studies. Overall, the conversion of rubber into oil palm plantations showed no significant impact on most of the soil properties and soil hydrology after twelve years of conversion.

ANALYSIS OF THE AVAILABILITY AND IDENTIFICATION OF PUBLIC GREEN OPEN SPACES IN GKU 1 AND GKU 2 AT INSTITUT TEKNOLOGI SUMATERA CAMPUS

Institut Teknologi Sumatera (ITERA) is a higher education institution located in the village of Way Huwi, South Lampung Regency. It was established to fulfill the educational needs centered on the island of Suamtera. ITERA campus was formerly a green area used for rubber plantations and forests which underwent transformation due to the demand for academic buildings. This transformations is ecidenced by the construction of the General Lecture Building (GKU) and Engineering Laboratory Building (Labtek) 1-4. This reserarch focuses on GKU 1 and 2, which serve as the central academic hubs for three faculties of ITERA. The aim is to identify issues related to the availability of public green open spaces in each building. Both GKU building have the potential to function as communal zones that can be utilized for discussions, relaxation, and studying due to their distinct characteristics in terms of green space forms and types. The research methodology employs both quantitative and qualitative methods, such as parameters of Responsive Environments, The Likert Scale, and interviews related to the questionnaire, with the primary target audience being ITERA’s students. The research results highlight various shortcomings and advantages in each GKU building. Recommendarions for improvemenr are expected to refine the research outcomes for ITERA.

Growth of Rubber Seeds (Hevea brasiliensis Muell.Arg) from Sleeping Eye Stum by Applying Organic Fertilizer Bulk and Liquid Herbal Waste

The organic fertilizer derived from herbal medicine waste in both bulk and liquid form is rich in macro and micro nutrients as well as decomposing microbes and probiotic bacteria needed to improve soil chemical properties. These fertilisers can be used to obtain better growth of rubber seedlings, especially rubber seedlings of sleeping eye origin. The objectives of this study was(1) to determine the effect of organic fertilizer and liquid bulk herbs Against Waste growth and (2) to know nutrient uptake of N, P, and K seedling stum Sleep eye. The study was conducted in a 4 x 3 factorial experiment arranged in a completely randomized design (CRD) with five replications. The first factor is the concentration of organic liquid fertilizer consisting of four in the standard: h0 = 0 ml L-1 of air (0%); h1 = 2 ml L-1 air (0.2%); h2 = 4ml L-1 air (0.4%); h3 = 6ml L-1 air (0.6%). The second factor is the dose of organic fertilizer consists of three levels: (b0 = 0 mg ha-1: b1 = 5 mg ha-1: b2 = 10 Mg ha-1). Data were analyzed with Analysis of Variant and continued with Duncan's Multiple Range Test 5% level. The results showed that the dosage of bulk organic fertilizers was significantly different at the level of 5% of the uptake of nitrogen, other observations were not significantly different. While the treatment of liquid organic fertilizer was highly significantly different at the level of 1% of nitrogen absorption, other observations were not significantly different. No real effect on their interaction in all observations. The treatment dose of organic fertilizer 5 Mg ha-1 and the treatment of liquid organic fertilizer 4 ml L-1 provided the highest results in leaf area of 586.46 cm2 per plant compared to the control treatment of 181.06 cm2 per plant. The treatment of bulk organic fertilizer dose and liquid organic fertilizer concentration predicted P2O5 nutrient uptake per rubber plant did not show significant differences. While the treatment of doses of bulk organic fertilizer and concentrations of liquid organic fertilizer is thought to be potassium nutrient uptake per rubber plant does not show significant differences, but can be seen from the growth of diameter, number of leaves, and leaf area.

A study on spatio-temporal trend of rubber leaf fall phenomenon using planetscope multi-index vegetation imagery in relations to climatological conditions

Background: Rubber plants are one of the most important plantation commodities in Indonesia. However, rubber production has declined due to leaf fall disease caused by the pathogen Pestalotiopsis sp. This study aims to analyze the spatial and temporal distribution of rubber plant leaf fall disease using multi-vegetation indices from PlanetScope imagery, as well as to analyze the influence of climatological conditions on the disease. Methods: The research was conducted at the Sembawa Rubber Research Center Garden, South Sumatra, using PlanetScope imagery data and climatological data in 2017 (before leaf fall) and 2023 (after leaf fall). Finding: Spatially, the 2023 leaf fall occurred in almost the entire garden area with poor to moderate levels. Blocks 2013D, 2012F, and 2009F experienced the most severe levels, with a total defoliated area reaching 396.76 ha. Analysis of monthly variations in vegetation index values revealed a decrease in values during leaf fall due to Pestalotiopsis sp., specifically in February, May, and September 2023. Statistical test results showed significant differences in vegetation index values between 2017 and 2023. Furthermore, based on Spearman's correlation analysis, there was a positive correlation between vegetation index values and humidity, but no significant correlation with rainfall and temperature. Conclusion: This research provides insights into mapping and monitoring rubber leaf fall disease using remote sensing data and climatological factors, which can be used for more effective rubber plantation management. However, the study has some limitations: monthly Planet data for 2017 is not fully available, several Planet image scenes from 2017 still have more than 50% cloud cover, and there may be biases as plants falling into the low health class are included in the high range of vegetation index values. Novelty/Originality of this Study: The study employs multi-vegetation indices derived from high-resolution PlanetScope imagery to detect and assess rubber leaf fall disease (LFD) within a plantation environment. By integrating spatial and temporal analyses with climatological data, the research provides a precise and comprehensive method for monitoring LFD and understanding its environmental determinants, thereby enhancing traditional rubber plantation management practices.

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.

Rubber Plantations as Mosquito Breeding Ecosystems: A Global Review

Rubber Plantations as Mosquito Breeding Ecosystems: A Global Review

Dari Petani Subsisten Ke Ekonomi Pasar

Independent oil palm plantations in the region are extensive compared to other local crop production. Oil palm has become an important plantation product for local communities. Oil palm plantations significantly change the socio-economic and environmental conditions of local communities. Oil palm plantations in the sub-district contribute significantly more to plantation production than other small-scale crops. The purpose of this study was to investigate and analyze the transition of small-scale agriculture to a market economy and to determine the factors driving this change. This research was conducted in Parindu sub-district, considering that oil palm plantations account for 61.33% of the area. This research uses a qualitative descriptive method. Sampling was done using target sampling. Data collection techniques were conducted through observation, in-depth interviews, and documentation. The triangulation technique was used to check the validity of the data. The data analysis method used the Miles and Hubermen analysis model (data reduction, presentation, and review). The informants in this study were independent oil palm farmers. The research found that before the introduction of market-oriented commercial farming systems, the Parindu community practiced subsistence farming, shifting cultivation and rubber plantations, and the results were sufficient to meet the needs of their families. They did not cultivate rubber as their main job, but as a side job in between their work as farmers. The desire to fulfill family needs became a strong foundation for the transformation of the agricultural economy from subsistence farming to the field of product marketing through the market economy. This change affected farmers' lifestyles, which were reflected in their possessions and assets. Property and wealth clearly increase honor and dignity as well as social status.

Pelestarian Pakaian Adat Melayu Riau Bagi Remaja di Provinsi Riau

Riau Province is an Indonesian province located on the east coast of the central island of Sumatra. Its coastal area borders the Strait of Malacca. Until 2004, the province also included the Riau Islands, a large group of small islands (the main islands include Batam Island and Bintan Island) located east of Sumatra and south of Singapore. The archipelago was split into its own province in July 2004. The capital and largest city in Riau province is Pekanbaru, and the other major city after Pekanbaru is Dumai. Riau is currently one of the richest provinces in Indonesia, and its resources are dominated by natural resources, especially petroleum, natural gas, rubber, oil palm and fiber plantations. along with the abundance of natural resources, Riau is also famous for its rich traditions and culture, both physical and non-physical that are inherent in the Riau people themselves. one of the physical cultures in Riau is Riau Malay traditional clothing. The people in Riau are dominated by the Malay tribe, where this tribe is also influenced by the Malay culture in Sumatra, Malaysia, Singapore. due to the close proximity of the region. characterized by similarities in dress or dress that has its own characteristics. the people of Riau usually wear their traditional clothes at major events, such as traditional ceremonies, holidays, official events.

Rubber-Based Agroforestry Systems Associated with Food Crops: A Solution for Sustainable Rubber and Food Production?

Agroforestry is often seen as a sustainable land-use system for agricultural production providing ecosystem services. Intercropping with food crops leads to equal or higher productivity than monoculture and results in food production for industry and subsistence. Low rubber price and low labor productivity in smallholdings have led to a dramatic conversion of rubber plantations to more profitable crops. The literature analysis performed in this paper aimed at better understanding the ins and outs that could make rubber-based agroforestry more attractive for farmers. A comprehensive search of references was conducted in March 2023 using several international databases and search engines. A Zotero library was set up consisting of 415 scientific references. Each reference was carefully read and tagged in several categories: cropping system, country, main tree species, intercrop type, intercrop product, level of product use, discipline of the study, research topic, and intercrop species. Of the 232 journal articles, 141 studies were carried out on rubber agroforestry. Since 2011, the number of studies per year has increased. Studies on rubber-based agroforestry systems are performed in most rubber-producing countries, in particular in Indonesia, Thailand, China, and Brazil. These studies focus more or less equally on perennials (forest species and fruit trees), annual intercrops, and mixed plantations. Of the 47 annual crops associated with rubber in the literature, 20 studies dealt with rice, maize, banana, and cassava. Agronomy is the main discipline in the literature followed by socio-economy and then ecology. Only four papers are devoted to plant physiology and breeding. The Discussion Section has attempted to analyze the evolution of rubber agroforestry research, progress in the selection of food crop varieties adapted to agroforestry systems, and to draw some recommendations for rubber-based agroforestry systems associated with food crops.

Design and experimental evaluation of a variable pesticide application control system for the air-assisted rubber tree powder sprayer.

In order to address the issues of uneven pesticide deposition and low pesticide utilization in rubber gardens caused by the traditional diffuse plant protection spraying method, this study focuses on the air-assisted powder sprayer and proposes a variable pesticide application control system. A variable pesticide application decision-making model integrating the leaf area index (LAI) was designed based on powdery mildew control standards and individual rubber tree information. According to the target powder spraying accuracy requirements, a control model of the air velocity adjustment device was established and a fuzzy proportional-integral-differential (PID) air velocity control system was developed. The simulation results indicate that the wind speed control system exhibits a maximum overshoot of 2.18% and an average response time of 1.48 s. The field experiment conducted in a rubber plantation revealed that when the air-assisted powder sprayer operates in the variable powder spraying mode, the average response time of the control system is 2.5 s. The control accuracy of each executive mechanism exceeded 95.9%. The deposition coefficient of variation (CV) at different canopy heights was relatively consistent, with values of 35.38%, 36.26% and 36.90%. In comparison to the quantitative mode, the variable mode showed a significant 20.03% increase in the effective utilization rate of sulfur powder. These research findings provide valuable technical support for the advancement of mechanized variable powder spraying equipment in rubber tree cultivation. © 2024 Society of Chemical Industry.

Reprogramming of DNA methylation and changes of gene expression in grafted Hevea brasiliensis.

Rubber tree (Hevea brasiliensis) is reproduced by bud grafting for commercial planting, but significant intraclonal variations exist in bud-grafted clones. DNA methylation changes related to grafting may be partly responsible for intraclonal variations. In the current study, whole-genome DNA methylation profiles of grafted rubber tree plants (GPs) and their donor plants (DPs) were evaluated by whole-genome bisulfite sequencing. Data showed that DNA methylation was downregulated and DNA methylations in CG, CHG, and CHH sequences were reprogrammed in GPs, suggesting that grafting induced the reprogramming of DNA methylation. A total of 5,939 differentially methylated genes (DMGs) were identified by comparing fractional methylation levels between GPs and DPs. Transcriptional analysis revealed that there were 9,798 differentially expressed genes (DEGs) in the DP and GP comparison. A total of 1,698 overlapping genes between DEGs and DMGs were identified. These overlapping genes were markedly enriched in the metabolic pathway and biosynthesis of secondary metabolites by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Global DNA methylation and transcriptional analyses revealed that reprogramming of DNA methylation is correlated with gene expression in grafted rubber trees. The study provides a whole-genome methylome of rubber trees and an insight into the molecular mechanisms underlying the intraclonal variations existing in the commercial planting of grafted rubber trees.