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Oil palm is presently the most important oil-producing crop worldwide in terms of oil production and consumption. However, oil palm cultivation faces important challenges such as adverse climatic conditions, expensive fertilization requirements, and fungal pathogens, including Ganoderma . Intense efforts in oil palm breeding are devoted to improving both oil production yield and resistance to environmental cues. Metabolomics can be of interest because it provides many quantitative traits and metabolic signatures that can be selected for to optimize oil palm performance. Here, we briefly review how metabolomics can help oil palm breeding, and to do so, we give examples of recent metabolomics analyses and provide a roadmap to use metabolomics-assisted breeding.

Agriculture is expanding rapidly across the tropics. While cultivation can boost socioeconomic conditions and food security, it also threatens native ecosystems. Oil palm (Elaeis guineensis), which is grown pantropically, is the most productive vegetable oil crop worldwide. The impacts of oil palm cultivation have been studied extensively in Southeast Asia and - to a lesser extent - in Latin America but, in comparison, very little is known about its impacts in Africa: oil palm's native range, and where cultivation is expanding rapidly. In this paper, we introduce a large-scale research programme - the Sustainable Oil Palm in West Africa (SOPWA) Project - that is evaluating the relative ecological impacts of oil palm cultivation under traditional (i.e., by local people) and industrial (i.e., by a large-scale corporation) management in Liberia. Our paper is twofold in focus. First, we use systematic mapping to appraise the literature on oil palm research in an African context, assessing the geographic and disciplinary focus of existing research. We found 757 publications occurring in 36 African countries. Studies tended to focus on the impacts of palm oil consumption on human health and wellbeing. We found no research that has evaluated the whole-ecosystem (i.e., multiple taxa and ecosystem functions) impacts of oil palm cultivation in Africa, a knowledge gap which the SOPWA Project directly addresses. Second, we describe the SOPWA Project's study design and-using canopy cover, ground vegetation cover, and soil temperature data as a case study-demonstrate its utility for assessing differences between areas of rainforest and oil palm agriculture. We outline the socioecological data collected by the SOPWA Project to date and describe the potential for future research, to encourage new collaborations and additional similar projects of its kind in West Africa. Increased research in Africa is needed urgently to understand the combined ecological and sociocultural impacts of oil palm and other agriculture in this unique region. This will help to ensure long-term sustainability of the oil palm industry-and, indeed, all tropical agricultural activity-in Africa., Competing Interests: Declaration of competing interest Co-authors with a Forestry Development Authority (FDA), Golden Veroleum Liberia (GVL), and Sinar Mas Agro Resources and Technology Research Institute (SMARTRI) affiliation were employed by their respective institutes while research was conducted. University of Cambridge retains all intellectual property rights and data-use for all researchers involved in this study. This research is therefore a collaboration between all affiliated parties., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Well-designed approaches to ecological restoration can benefit nature and society. This is particularly the case in tropical agroecosystems, where restoration can provide substantial socioecological benefits at relatively low costs. To successfully restore tropical agroecosystems and maximise benefits, initiatives must begin by considering 'who' should be involved in and benefit from restoration, and 'what', 'where', and 'how' restoration should occur. Based on collective experience of restoring tropical agroecosystems worldwide, we present nine actions to guide future restoration of these systems, supported by case studies that demonstrate our actions being used successfully in practice and highlighting cases where poorly designed restoration has been damaging. We call for increased restoration activity in tropical agroecosystems during the current UN Decade on Ecosystem Restoration., Competing Interests: Declaration of interests Authors are affiliated with the restoration projects that are outlined in the case studies in this manuscript: A.R. (Restoring the Madagascan Fandriana-Marolambo landscape); M.D.P., A.A.K.A., D.B., J.-P.C., P.H., H.K., M.N., E.C.T., D.C.Z., and S.H.L. (Restoring cultivated oil palm landscapes in Indonesia and Malaysia); F.A. and A.D.G.C. (Restoring the Brazilian Atlantic rainforest)., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Extensive oil palm plantations have often resulted in the decrease of soil organic carbon (SOC). Several options exist to counter this, such as recycling empty fruit bunches (EFB) as a soil amendment. However, the extent to which EFB increase SOC has been disputed. Since EFB could also be used as a climate change mitigation tool, it is necessary to truly understand their impact on SOC. The investigation of the impact of nine EFB treatments (differing in frequency and application rates) on a 27-year-old large-scale experiment (Lampung, Sumatra, Indonesia) revealed that, while EFB impacts are heterogeneous throughout the plantation, they can positively affect total SOC and permanganate oxidisable carbon (POX-C) both at shallow and deep depths (measured up to 100 cm). POX-C was closely correlated to SOC, but showed significant increases compared to the untreated control in all treatments, while total SOC was only increased in a few treatments with small and frequent rates of EFB application. Overall, between 12 (±16) and 56 (±12) t ha - 1 of carbon were sequestered under the harvesting path after 21 years. Focussing on the mineral nutrition value of the EFB, oil palm companies apply a rate of 60 t of EFB every second year for their commercial production, and the analysis of three commercial plots showed that the commercial rate only increased POX-C while it had no effect on the total SOC and SOC stocks. It seems obvious that a change of paradigm is necessary to consider EFB recycling as a new management perspective, where the potential for carbon sequestration becomes an important variable for climate change mitigation besides the initial objective of integrating EFB application into the fertiliser management plan of a plantation., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Asian weaver ants ( Oecophyllasmaragdina ) are an important biocontrol agent in agricultural habitats. We conducted surveys in oil palm plantations in Riau, Indonesia for an obligate myrmecophilous butterfly larvae, Liphyrabrassolis (Lepidoptera, Lycaenidae), that is known to consume weaver ant larvae in other habitat types. We found L.brassolis larvae in five of the twenty nests surveyed, with larval presence not being related to weaver ant nest size. We also observed L.brassolis larvae in a weaver ant mass rearing facility. This is the first report of L.brassolis from oil palm plantations and may have implications for the use of weaver ants as biological control agents., (Andreas Dwi Advento, Kalsum M Yusah, Hasber Salim, Mohammad Naim, Jean-Pierre Caliman, Tom Maurice Fayle.)

Expansion of oil palm has caused widespread declines in biodiversity and changes in ecosystem functioning across the tropics. A major driver of these changes is loss of habitat heterogeneity as forests are converted into oil palm plantations. Therefore, one strategy to help support biodiversity and functioning in oil palm is to increase habitat heterogeneity, for instance, by retaining forested buffers around rivers when new plantations are established, or maintaining buffers made of mature oil palms ("mature palm buffers") when old plantations are replanted. While forested buffers are known to benefit oil palm systems, the impacts of mature palm buffers are less certain. In this study, we assessed the benefits of mature palm buffers, which were being passively restored (in this case, meaning that buffers were treated with no herbicides, pesticides, or fertilizers) by sampling environmental conditions and arthropods within buffers and in surrounding non-buffer areas (i.e., areas that were 25 and 125 m from buffers, and receiving normal business-as-usual management) across an 8-year chronosequence in industrial oil palm plantations (Sumatra, Indonesia). We ask (1) Do environmental conditions and biodiversity differ between buffer and non-buffer areas? (2) Do buffers affect environmental conditions and biodiversity in adjacent non-buffer areas (i.e., areas that were 25 m from buffers)? (3) Do buffers become more environmentally complex and biodiverse over time? We found that buffers can have environmental conditions (canopy openness, variation in openness, vegetation height, ground cover, and soil temperature) and levels of arthropod biodiversity (total arthropod abundance and spider abundance in the understory and spider species-level community composition in all microhabitats) that are different from those in non-buffer areas, but that these differences are inconsistent across the oil palm commercial life cycle. We also found that buffers might contribute to small increases in vegetation height and changes in ground cover in adjacent non-buffer areas, but do not increase levels of arthropod biodiversity in these areas. Finally, we found that canopy openness, variation in openness, and ground cover, but no aspects of arthropod biodiversity, change within buffers over time. Collectively, our findings indicate that mature palm buffers that are being passively restored can have greater environmental complexity and higher levels of arthropod biodiversity than non-buffer areas, particularly in comparison to recently replanted oil palm, but these benefits are not consistent across the crop commercial life cycle. If the goal of maintaining riparian buffers is to consistently increase habitat heterogeneity and improve biodiversity, an alternative to mature palm buffers or a move toward more active restoration of these areas is, therefore, probably required., (© 2022 The Authors. Ecological Applications published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

To respect the Paris agreement targeting a limitation of global warming below 2°C by 2100, and possibly below 1.5°C, drastic reductions of greenhouse gas emissions are mandatory but not sufficient. Large-scale deployment of other climate mitigation strategies is also necessary. Among these, increasing soil organic carbon (SOC) stocks is an important lever because carbon in soils can be stored for long periods and land management options to achieve this already exist and have been widely tested. However, agricultural soils are also an important source of nitrous oxide (N 2 O), a powerful greenhouse gas, and increasing SOC may influence N 2 O emissions, likely causing an increase in many cases, thus tending to offset the climate change benefit from increased SOC storage. Here we review the main agricultural management options for increasing SOC stocks. We evaluate the amount of SOC that can be stored as well as resulting changes in N 2 O emissions to better estimate the climate benefits of these management options. Based on quantitative data obtained from published meta-analyses and from our current level of understanding, we conclude that the climate mitigation induced by increased SOC storage is generally overestimated if associated N 2 O emissions are not considered but, with the exception of reduced tillage, is never fully offset. Some options (e.g. biochar or non-pyrogenic C amendment application) may even decrease N 2 O emissions., (© 2020 John Wiley & Sons Ltd.)

The extraction of relevant wavelengths from a large dataset of Near Infrared Spectroscopy (NIRS) is a significant challenge in vibrational spectroscopy research. Nonetheless, this process allows the improvement in the chemical interpretability by emphasizing the chemical entities related to the chemical parameters of samples. With the complexity in the dataset, it may be possible that irrelevant wavelengths are still included in the multivariate calibration. This yields the computational process to become unnecessary complex and decreases the accuracy and robustness of the model. In multivariate analysis, Partial Least Square Regression (PLSR) is a method commonly used to build a predictive model from NIR spectral data. However, in the PLSR method and common commercial chemometrics software, there is no standard wavelength selection procedure applied to screen the irrelevant wavelengths. In this study, a new robust wavelength selection procedure called the modified VIP-MCUVE (mod-VIP-MCUVE) using Filter-Wrapper method and input scaling strategy is introduced. The proposed method combines the modified Variable Importance in Projection (VIP) and modified Monte Carlo Uninformative Variable Elimination (MCUVE) to calculate the scale matrix of the input variable. The modified VIP uses the orthogonal components of Partial Least Square (PLS) in investigating the informative variable in the model by applying the amount of variation both in X and y{SSX,SSY}, simultaneously. The modified MCUVE uses a robust reliability coefficient and a robust tolerance interval in the selection procedure. To evaluate the superiority of the proposed method, the classical VIP, MCUVE, and autoscaling procedure in classical PLSR were also included in the evaluation. Using artificial data with Monte Carlo simulation and NIR spectral data of oil palm ( Elaeis guineensis Jacq.) fruit mesocarp, the study shows that the proposed method offers advantages to improve model interpretability, to be computationally extensive, and to produce better model accuracy.

In practice, the collected spectra are very often composes of complex overtone and many overlapping peaks which may lead to misinterpretation because of its significant nonlinear characteristics. Using linear solution might not be appropriate. In addition, with a high-dimension of dataset due to large number of observations and data points the classical multiple regressions will neglect to fit. These complexities commonly will impact to multicollinearity problem, furthermore the risk of contamination of multiple outliers and high leverage points also increases. To address these problems, a new method called Kernel Partial Diagnostic Robust Potential (KPDRGP) is introduced. The method allows the nonlinear solution which maps nonlinearly the original input X matrix into higher dimensional feature mapping with corresponds to the Reproducing Kernel Hilbert Spaces (RKHS). In dimensional reduction, the method replaces the dot products calculation of elements in the mapped data to a nonlinear function in the original input space. To prevent the contamination of the multiple outlier and high leverage points the robust procedure using Diagnostic Robust Generalized Potentials (DRGP) algorithm was used. The results verified that using the simulation and real data, the proposed KPDRGP method was superior to the methods in the class of non-kernel and some other robust methods with kernel solution., (© 2020 The Author(s).)

Conversion of forest to oil palm plantations results in a significant loss of biodiversity. Despite this, first-cycle oil palm plantations can sustain relatively high biodiversity compared to other crops. However, the long-term effects of oil palm agriculture on flora and fauna are unknown. Oil palm has a 25-year commercial lifespan before it must be replanted, due to reduced productivity and difficulty of harvesting. Loss of the complex vegetation structure of oil palm plantations during the replanting process will likely have impacts on the ecosystem at a local and landscape scale. However, the effect of replanting on biodiversity is poorly understood.Here, we investigate the effects of replanting oil palm on soil macrofauna communities. We assessed ordinal richness, abundance, and community composition of soil macrofauna in first- (25- to 27-year-old) and second-cycle oil palm (freshly cleared, 1-year-old, 3-year-old, and 7-year-old mature).Macrofauna abundance and richness drastically declined immediately after replanting. Macrofauna richness showed some recovery 7 years after replanting, but was still 19% lower than first-cycle oil palm. Macrofauna abundance recovered to similar levels to that of first-cycle oil palm plantations, 1 year after replanting. This was mainly due to high ant abundance, possibly due to the increased understory vegetation as herbicides are not used at this age. However, there were subsequent declines in macrofauna abundance 3 and 7 years after replanting, resulting in a 59% drop in macrofauna abundance compared to first-cycle levels. Furthermore, soil macrofauna community composition in all ages of second-cycle oil palm was different to first-cycle plantations, with decomposers suffering particular declines.After considerable biodiversity loss due to forest conversion for oil palm, belowground invertebrate communities suffer a second wave of biodiversity loss due to replanting. This is likely to have serious implications for soil invertebrate diversity and agricultural sustainability in oil palm landscapes, due to the vital ecosystem functions that soil macrofauna provide., Competing Interests: None declared.

Background and Aims: Enhancement of light harvesting in annual crops has successfully led to yield increases since the green revolution. Such an improvement has mainly been achieved by selecting plants with optimal canopy architecture for specific agronomic practices. For perennials such as oil palm, breeding programmes were focused more on fruit yield, but now aim at exploring more complex traits. The aim of the present study is to investigate potential improvements in light interception and carbon assimilation in the study case of oil palm, by manipulating leaf traits and proposing architectural ideotypes., Methods: Sensitivity analyses (Morris method and metamodel) were performed on a functional-structural plant model recently developed for oil palm which takes into account genetic variability, in order to virtually assess the impact of plant architecture on light interception efficiency and potential carbon acquisition., Key Results: The most sensitive parameters found over plant development were those related to leaf area (rachis length, number of leaflets, leaflet morphology), although fine attributes related to leaf geometry showed increasing influence when the canopy became closed. In adult stands, optimized carbon assimilation was estimated on plants with a leaf area index between 3.2 and 5.5 m2 m-2 (corresponding to usual agronomic conditions), with erect leaves, short rachis and petiole, and high number of leaflets on the rachis. Four architectural ideotypes for carbon assimilation are proposed based on specific combinations of organ dimensions and arrangement that limit mutual shading and optimize light distribution within the plant crown., Conclusions: A rapid set-up of leaf area is critical at young age to optimize light interception and subsequently carbon acquisition. At the adult stage, optimization of carbon assimilation could be achieved through specific combinations of architectural traits. The proposition of multiple morphotypes with comparable level of carbon assimilation opens the way to further investigate ideotypes carrying an optimal trade-off between carbon assimilation, plant transpiration and biomass partitioning.

Expansion of oil palm agriculture is currently one of the main drivers of habitat modification in Southeast Asia. Habitat modification can have significant effects on biodiversity, ecosystem function, and interactions between species by altering species abundances or the available resources in an ecosystem. Increasing complexity within modified habitats has the potential to maintain biodiversity and preserve species interactions. We investigated trophic interactions between Argyrodes miniaceus, a cleptoparasitic spider, and its Nephila spp . spider hosts in mature oil palm plantations in Sumatra, Indonesia. A. miniaceus co-occupy the webs of Nephila spp . females and survive by stealing prey items caught in the web. We examined the effects of experimentally manipulated understory vegetation complexity on the density and abundance of A. miniaceus in Nephila spp . webs. Experimental understory treatments included enhanced complexity, standard complexity, and reduced complexity understory vegetation, which had been established as part of the ongoing Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Project. A. miniaceus density ranged from 14.4 to 31.4 spiders per square meter of web, with significantly lower densities found in reduced vegetation complexity treatments compared with both enhanced and standard treatment plots. A. miniaceus abundance per plot was also significantly lower in reduced complexity than in standard and enhanced complexity plots. Synthesis and applications : Maintenance of understory vegetation complexity contributes to the preservation of spider host-cleptoparasite relationships in oil palm plantations. Understory structural complexity in these simplified agroecosystems therefore helps to support abundant spider populations, a functionally important taxon in agricultural landscapes. In addition, management for more structurally complex agricultural habitats can support more complex trophic interactions in tropical agroecosystems.

Crop residue management is an important agricultural practice that has a high potential to improve soil health and optimize crop production. Compared to annual crops, relatively little is known about crop residue management effects on the yield and temporal stability of perennial crop production. This study focused on oil palm ( Elaeis guineensis ), an important tropical crop that had expanded rapidly over the past decades. We aimed to understand the effects of applying a major oil palm residue, the empty fruit bunch, on crop yield and temporal stability of production. We compared 15 years of crop yield performance from a field trial in Sumatra, Indonesia. The treatments included empty fruit bunch application of three application rates (30, 60, and 90 t ha -1  year -1 ), and a reference treatment of chemical fertilizers with no addition of empty fruit bunch. Compared to the reference treatment, the cumulative crop yield over 15 years under low, medium, and high application rates of empty fruit bunch increased by 2.4, 5.9, and 4.8%, respectively. The annual crop yield and temporal stability in production were not significantly different between treatments. Soil organic carbon was significantly higher under medium application rate of empty fruit bunch compared to that under the chemical fertilizer treatment. Soil organic carbon and relative humidity were positively associated with annual crop yield with a time lag of 2 years. This study is the first to show that both crop yield and temporal variability of oil palm production can be maintained under crop residue application, compared to chemical fertilizer treatment. Furthermore, climatic conditions had strong effects on the temporal variability of oil palm production. These findings will inform the design of optimal empty fruit bunch application schemes that enhance sustainable intensification of oil palm cultivation., (© The Author(s) 2017.)

Three-dimensional (3D) reconstruction of plants is time-consuming and involves considerable levels of data acquisition. This is possibly one reason why the integration of genetic variability into 3D architectural models has so far been largely overlooked. In this study, an allometry-based approach was developed to account for architectural variability in 3D architectural models of oil palm (Elaeis guineensis Jacq.) as a case study. Allometric relationships were used to model architectural traits from individual leaflets to the entire crown while accounting for ontogenetic and morphogenetic gradients. Inter- and intra-progeny variabilities were evaluated for each trait and mixed-effect models were used to estimate the mean and variance parameters required for complete 3D virtual plants. Significant differences in leaf geometry (petiole length, density of leaflets, and rachis curvature) and leaflet morphology (gradients of leaflet length and width) were detected between and within progenies and were modelled in order to generate populations of plants that were consistent with the observed populations. The application of mixed-effect models on allometric relationships highlighted an interesting trade-off between model accuracy and ease of defining parameters for the 3D reconstruction of plants while at the same time integrating their observed variability. Future research will be dedicated to sensitivity analyses coupling the structural model presented here with a radiative balance model in order to identify the key architectural traits involved in light interception efficiency., (© The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

High fertilizer input is necessary to sustain high yields in oil palm agroecosystems, but it may endanger neighboring aquatic ecosystems when excess nutrients are transported to waterways. In this study, the hydrochemical dynamics of groundwater and streams under baseflow conditions were evaluated with bi-monthly measurements for 1 year on 16 watersheds. Hydrochemical measurements were related to the spatial distribution of soil and fertilization practices across a landscape of 100 km(2), dominated by oil palm cultivation, in Central Sumatra, Indonesia. The low nutrient concentrations recorded in streams throughout the landscape indicated that the mature oil palm plantations in this study did not contribute to eutrophication of aquatic ecosystems. This was ascribed to high nutrient uptake by oil palm, a rational fertilizer program, and dilution of nutrient concentrations due to heavy rainfall in the study area. Soil type controlled dissolved inorganic N and total P fluxes, with greater losses of N and P from loamy-sand uplands than loamy lowlands. Organic fertilization helped to reduce nutrient fluxes compared to mineral fertilizers. However, when K inputs exceeded the oil palm requirement threshold, high K export occurred during periods when groundwater had a short residence time. For higher nutrient use efficiency in the long term, the field-scale fertilizer management should be complemented with a landscape-scale strategy of fertilizer applications that accounts for soil variability.

Source/sink ratios are known to be one of the main determinants of oil palm growth and development. A long-term experiment (9 years) was conducted in Indonesia on mature oil palms subjected to continuous bunch ablation and partial defoliation treatments to artificially modify source/sink ratios. During the experiment, all harvested bunches were dissected and phenological measurements were carried out to analyse the effect of source/sink ratios on yield components explaining variations in bunch number, the number of fruits per bunch and oil dry weight per fruit. An integrative variable (supply/demand ratio) describing the ratio between the assimilate supply from sources and the growing organ demand for carbohydrate was computed for each plant on a daily basis from observations of the number of developing organs and their sink strength, and of climate variables. Defoliation and bunch ablation affected the bunch number and the fruit number per bunch. Variations in bunch number per month were mainly due to variations in the fraction of aborted inflorescence and in the ratio between female and male inflorescences. Under fluctuating trophic conditions, variations in fruit number per bunch resulted both from changes in fruit-set and in the number of branches (rachillae) per inflorescence. For defoliated plants, the decrease in the number of developing reproductive sinks appeared to be sufficient to maintain fruit weight and oil concentration at the control level, without any major decrease in the concentration of non-structural carbohydrate reserves. Computation of the supply/demand ratio revealed that each yield component had a specific phase of sensitivity to supply/demand ratios during inflorescence development. Establishing quantitative relationships between supply/demand ratios, competition and yield components is the first step towards a functional model for oil palm.

For oil palm, yield variation is in large part due to variation in the number of harvested bunches. Each successively-produced phytomer carries a female (productive), male or aborted inflorescence. Since phytomer development takes 3-4 years and nearly two phytomers are produced per month, many inflorescences develop in parallel but have different phenological stages. Environment-dependent developmental rate, sex and abortion probability determine bunch productivity, which, in turn, affects other phytomers via source-sink relationships. Water deficit, solar radiation, temperature and day length are considered key external factors driving variation. Their impact is difficult to predict because of system complexity. To address this question we built a simple model (ECOPALM) to simulate the variation in number of harvested bunches. In this model, trophic competition among organs, expressed through a plant-scale index (Ic), drives sex determination and inflorescence abortion during specific sensitive phases at phytomer level. As a supplemental hypothesis, we propose that flowering is affected by photoperiod at phytomer level during a sensitive phase, thus, contributing to seasonal production peaks. The model was used to determine by parameter optimisation the influence of Ic and day length on inflorescence development and the stages at which inflorescences are sensitive to these signals. Parameters were estimated against observation of number of harvested bunches in Ivory Coast using a genetic algorithm. The model was then validated with field observations in Benin and Indonesia. The sensitive phases determined by parameter optimisation agreed with independent experimental evidence, and variation of Ic explained both sex and abortion patterns. Sex determination seemed to coincide with floret meristem individualisation and occurred 29-32 months before bunch harvest. The main abortion stage occurred 10 months before harvest - at the beginning of rapid growth of the inflorescence. Simulation results suggest involvement of photoperiod in the determination of bunch growth dynamics. This study demonstrates that simple modelling approaches can help extracting ecophysiological information from simple field observations on complex systems.

Rodent control is an important issue in human health and agriculture. Oil palm plantations are rapidly expanding in Indonesia and this is having a major economic and ecological impact. Rodent control in oil palm plantations is based principally on the use of anti-vitamin K (AVK), the main anticoagulant used being coumatetralyl, a first-generation AVK. We conducted a comparative study in two well established oil palm plantations in Indonesia: (1) one without chemical control in Riau and (2) another with intensive coumatetralyl use on Bangka Island. Rat species were identified by the molecular barcoding method. Susceptibility to coumatetralyl was then assessed within the two populations and we screened for mutations in vkorc1, which encodes the molecular target of AVK. Different species were found in the two areas: Rattus tiomanicus in Riau, and a mix of R. tanezumi and a close relative one in Bangka. The rats in Riau were much more susceptible to coumatetralyl than those in Bangka. This study is the first to demonstrate physiological tolerance to AVK in these species. vkorc1 displayed low levels of polymorphism, and no SNP was associated with the high-tolerance phenotypes of R. tanezumi clade, even those exposed to very high concentrations (32 × the effective dose of 0.36 mg kg(-1)). The biochemical basis of this tolerance remains unknown, but may involve the vkorc1 promoter and/or cytochrome P450 metabolism. We discuss our results and the selective role of anticoagulant use in the occurrence of phenotypic tolerance.

Fungal disease detection in perennial crops is a major issue in estate management and production. However, nowadays such diagnostics are long and difficult when only made from visual symptom observation, and very expensive and damaging when based on root or stem tissue chemical analysis. As an alternative, we propose in this study to evaluate the potential of hyperspectral reflectance data to help detecting the disease efficiently without destruction of tissues. This study focuses on the calibration of a statistical model of discrimination between several stages of Ganoderma attack on oil palm trees, based on field hyperspectral measurements at tree scale. Field protocol and measurements are first described. Then, combinations of pre-processing, partial least square regression and linear discriminant analysis are tested on about hundred samples to prove the efficiency of canopy reflectance in providing information about the plant sanitary status. A robust algorithm is thus derived, allowing classifying oil-palm in a 4-level typology, based on disease severity from healthy to critically sick stages, with a global performance close to 94%. Moreover, this model discriminates sick from healthy trees with a confidence level of almost 98%. Applications and further improvements of this experiment are finally discussed.

Background and Aims: Oil palm flowering and fruit production show seasonal maxima whose causes are unknown. Drought periods confound these rhythms, making it difficult to analyse or predict dynamics of production. The present work aims to analyse phenological and growth responses of adult oil palms to seasonal and inter-annual climatic variability., Methods: Two oil palm genotypes planted in a replicated design at two sites in Indonesia underwent monthly observations during 22 months in 2006-2008. Measurements included growth of vegetative and reproductive organs, morphology and phenology. Drought was estimated from climatic water balance (rainfall - potential evapotranspiration) and simulated fraction of transpirable soil water. Production history of the same plants for 2001-2005 was used for inter-annual analyses., Key Results: Drought was absent at the equatorial Kandista site (0 degrees 55'N) but the Batu Mulia site (3 degrees 12'S) had a dry season with variable severity. Vegetative growth and leaf appearance rate fluctuated with drought level. Yield of fruit, a function of the number of female inflorescences produced, was negatively correlated with photoperiod at Kandista. Dual annual maxima were observed supporting a recent theory of circadian control. The photoperiod-sensitive phases were estimated at 9 (or 9 + 12 x n) months before bunch maturity for a given phytomer. The main sensitive phase for drought effects was estimated at 29 months before bunch maturity, presumably associated with inflorescence sex determination., Conclusion: It is assumed that seasonal peaks of flowering in oil palm are controlled even near the equator by photoperiod response within a phytomer. These patterns are confounded with drought effects that affect flowering (yield) with long time-lag. Resulting dynamics are complex, but if the present results are confirmed it will be possible to predict them with models.

Background and Aims: Despite its simple architecture and small phenotypic plasticity, oil palm has complex phenology and source-sink interactions. Phytomers appear in regular succession but their development takes years, involving long lag periods between environmental influences and their effects on sinks. Plant adjustments to resulting source-sink imbalances are poorly understood. This study investigated oil palm adjustments to imbalances caused by severe fruit pruning., Methods: An experiment with two treatments (control and complete fruit pruning) during 22 months in 2006-2008) and six replications per treatment was conducted in Indonesia. Phenology, growth of above-ground vegetative and reproductive organs, leaf morphology, inflorescence sex differentiation, dynamics of non-structural carbohydrate reserves and light-saturated net photosynthesis (A(max)) were monitored., Key Results: Artificial sink limitation by complete fruit pruning accelerated development rate, resulting in higher phytomer, leaf and inflorescence numbers. Leaf size and morphology remained unchanged. Complete fruit pruning also suppressed the abortion of male inflorescences, estimated to be triggered at about 16 months before bunch maturity. The number of female inflorescences increased after an estimated lag of 24-26 months, corresponding to time from sex differentiation to bunch maturity. The most important adjustment process was increased assimilate storage in the stem, attaining nearly 50 % of dry weight in the stem top, mainly as starch, whereas glucose, which in controls was the most abundant non-structural carbohydrate stored in oil palm, decreased., Conclusions: The development rate of oil palm is in part controlled by source-sink relationships. Although increased rate of development and proportion of female inflorescences constituted observed adjustments to sink limitation, the low plasticity of plant architecture (constant leaf size, absence of branching) limited compensatory growth. Non-structural carbohydrate storage was thus the main adjustment process.

Oil palm (Elaeis guineensis Jacq.) is a perennial, tropical, monocotyledonous plant characterized by simple architecture and low phenotypic plasticity, but marked by long development cycles of individual phytomers (a pair of one leaf and one inflorescence at its axil). Environmental effects on vegetative or reproductive sinks occur with various time lags depending on the process affected, causing source-sink imbalances. This study investigated how the two instantaneous sources of carbon assimilates, CO(2) assimilation and mobilization of transitory non-structural carbohydrate (NSC) reserves, may buffer such imbalances. An experiment was conducted in Indonesia during a 22-month period (from July 2006 to May 2008) at two contrasting locations (Kandista and Batu Mulia) using two treatments (control and complete fruit pruning treatment) in Kandista. Measurements included leaf gas exchange, dynamics of NSC reserves and dynamics of structural aboveground vegetative growth (SVG) and reproductive growth. Drought was estimated from a simulated fraction of transpirable soil water. The main sources of variation in source-sink relationships were (i) short-term reductions in light-saturated leaf CO(2) assimilation rate (A(max)) during seasonal drought periods, particularly in Batu Mulia; (ii) rapid responses of SVG rate to drought; and (iii) marked lag periods between 16 and 29 months of environmental effects on the development of reproductive sinks. The resulting source-sink imbalances were buffered by fluctuations in NSC reserves in the stem, which mainly consisted of glucose and starch. Starch was the main buffer for sink variations, whereas glucose dynamics remained unexplained. Even under strong sink limitation, no negative feedback on A(max) was observed. In conclusion, the different lag periods for environmental effects on assimilate sources and sinks in oil palm are mainly buffered by NSC accumulation in the stem, which can attain 50% (dw:dw) in stem tops. The resulting dynamics of growth and production are complex because several dozen phytomers of different phenological ages develop at any given time and interact with a common pool of reserves.