Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    An integrated linkage map of interspecific backcross 2 (BC2) populations reveals QTLs associated with fatty acid composition and vegetative parameters influencing compactness in oil palm
    Yaakub, Zulkifli ; Kamaruddin, Katialisa ; Singh, Rajinder ; Mustafa, Suzana ; Marjuni, Marhalil ; Ting, Ngoot Chin ; Amiruddin, Mohd Din ; Leslie, Low Eng Ti ; Cheng-Li, Ooi Leslie ; Sritharan, Kandha ; Nookiah, Rajanaidu ; Jansen, Johannes ; Ong Abdullah, Meilina - \ 2020
    BMC Plant Biology 20 (2020)1. - ISSN 1471-2229 - 18 p.
    Compactness - Fatty acid composition - Interspecific hybrids - Oil palm - QTL

    BACKGROUND: Molecular breeding has opened new avenues for crop improvement with the potential for faster progress. As oil palm is the major producer of vegetable oil in the world, its improvement, such as developing compact planting materials and altering its oils' fatty acid composition for wider application, is important. RESULTS: This study sought to identify the QTLs associated with fatty acid composition and vegetative traits for compactness in the crop. It integrated two interspecific backcross two (BC2) mapping populations to improve the genetic resolution and evaluate the consistency of the QTLs identified. A total 1963 markers (1814 SNPs and 149 SSRs) spanning a total map length of 1793 cM were integrated into a consensus map. For the first time, some QTLs associated with vegetative parameters and carotene content were identified in interspecific hybrids, apart from those associated with fatty acid composition. The analysis identified 8, 3 and 8 genomic loci significantly associated with fatty acids, carotene content and compactness, respectively. CONCLUSIONS: Major genomic region influencing the traits for compactness and fatty acid composition was identified in the same chromosomal region in the two populations using two methods for QTL detection. Several significant loci influencing compactness, carotene content and FAC were common to both populations, while others were specific to particular genetic backgrounds. It is hoped that the QTLs identified will be useful tools for marker-assisted selection and accelerate the identification of desirable genotypes for breeding.

    Scenarios for withdrawal of oil palm plantations from peatlands in Jambi Province, Sumatra, Indonesia
    Afriyanti, Dian ; Hein, Lars ; Kroeze, Carolien ; Zuhdi, Mohammad ; Saad, Asmadi - \ 2019
    Regional Environmental Change 19 (2019)4. - ISSN 1436-3798 - p. 1201 - 1215.
    Carbon emission - Mitigation - Oil palm - Peatlands - Restore - Withdrawal
    In Indonesia, peatlands are still being converted into oil palm plantations. The associated fires and peat oxidation result in smoke and large carbon emissions. In the medium term, peatlands should be used for production systems that do not require (or require much less) drainage. In this context, this study aims to explore scenarios for the withdrawal of oil palm plantations from peatlands in Jambi province and the associated carbon emissions in the coming decades. We first analyzed past land-use change trends in Jambi peatlands. Then, we analyzed three scenarios for the future: (1) a baseline scenario, assuming further expansions by smallholders, but not by companies, (2) a scenario assuming withdrawal from peat by companies only, and (3) a scenario assuming withdrawal from peat by companies and smallholders. In both scenarios 1 and 2, it is assumed smallholders keep on expanding oil palm plantations in peatlands up to 2020 but not thereafter. To accommodate economic interests of growers, withdrawal of oil palm plantations is assumed to only take place when the palm trees are 25 years old and their productivity starts declining. Our study shows that there has been a rapid expansion of oil palm plantations in peatlands of Jambi from 30,000 ha in 1987 to 483,000 ha in 2014. In our baseline scenario, involving commitments from companies but not from smallholders, the area of oil palm further increases by 20% between 2014 and 2040; this implies that by 2040, almost all peatlands, including those in the buffer zone of Berbak National Park, will have been converted to plantations. The corresponding greenhouse gas emissions are 53 Mt CO 2 -equivalent per year (from both peat decomposition and fires). In the scenario assuming withdrawal of company plantations from peatlands, the plantation area will be reduced to half that in the baseline scenario in 2040. This would decrease CO 2 -equivalent emissions in 2040 to below 2010 levels (27.9 Mt per year). Our study shows that a substantial decrease in emissions is only possible in scenario 3 with an almost full withdrawal of plantations from peatlands by 2040. This reduces CO 2 -equivalent emissions to the level of 2000 (4.3 Mt per year) and leads to safeguarding the remaining pristine peat swamp forest in Berbak National Park.
    Do wealthy farmers implement better agricultural practices? An assessment of implementation of Good Agricultural Practices among different types of independent oil palm smallholders in Riau, Indonesia
    Jelsma, Idsert ; Woittiez, Lotte S. ; Ollivier, Jean ; Dharmawan, Arya Hadi - \ 2019
    Agricultural Systems 170 (2019). - ISSN 0308-521X - p. 63 - 76.
    Farmer typology - Indonesia - Intensification - Land use - Oil palm - Smallholders

    Palm oil has become a leading vegetable oil over the past 30 years and smallholder farmers in Indonesia, with more than 12 million hectare the world's largest producer of palm oil, have massively engaged in oil palm (Elaeis guineensis) cultivation. In Sumatra, where more than 60% of Indonesian palm oil is cultivated, smallholders currently cover roughly 50% of the oil palm area. The rapid expansion of palm oil however did not happen without controversy. In current efforts by the Indonesian government, NGO's and private sector to improve sector performance, smallholders are often characterized as the Achilles heel of the oil palm sector due to poor practices and low yields compared to companies. However, ‘oil palm smallholders’ is a container concept and there has been only limited research into smallholder diversity beyond the organised versus independent farmer dichotomy. This research delves into the implementation of Good Agricultural Practices (GAP) among seven types of independent smallholders in Rokan Hulu regency, Riau province. The research area consisted of a relative established agricultural area on mineral soils and a relative frontier, mostly on peat. Smallholder types ranged from small local farmers to large farmers who usually reside in urban areas far from their plantation and regard oil palm cultivation as an investment opportunity. The underlying hypothesis is that larger farmers have more capital and therefore implement better agricultural practices than small farmers, who are usually more cash constrained. A wide range of methods was applied, including farmer and farm surveys, remote sensing, tissue analysis and photo interpretation by experts. These methods provided data on fertilizer use, nutrient conditions in oil palms, planting material, planting patterns, and other management practices in the plantations. Results show that yields are poor, implementation of GAP are limited and there is much room for improvement among all farmer types. Poor planting materials, square planting patterns, and limited nutrient applications were particularly prevalent. This implies that farmers across different typologies opt for a low-input low-output system for a myriad of reasons and that under current conditions, initiatives such as improving access to finance or availability of good planting material alone are unlikely to significantly improve the productivity and sustainability of the smallholder oil palm sector.

    Why do smallholders plant biofuel crops? The ‘politics of consent’ in Mexico
    Castellanos-Navarrete, Antonio ; Jansen, Kees - \ 2017
    Geoforum 87 (2017). - ISSN 0016-7185 - p. 15 - 27.
    Biofuels - Hegemony - Jatropha curcas - Oil palm - Political ecology - Rural organisations
    Recent studies have addressed the social and environmental impacts of biofuel crops but seldom the question as to why rural producers engage in their production. It is particularly unclear how governments worldwide, especially in middle-income countries such as Brazil, Thailand, and Mexico, could enroll so many smallholders in biofuel cropping projects. Conventional views see yields and economic returns as main drivers for smallholder participation in biofuel production but ignore the role played by power and politics. This paper analyses the rapid biofuel expansions (oil palm, jatropha) in the southern Lacandon rainforest in Chiapas (Mexico) and their partial failure (jatropha) from a political ecology perspective. Our findings indicate that biofuel expansions in this region not only occurred for productive reasons, but also because biofuel programmes provided prospects for political gains through strengthened rural organisations. In contrast with emphasis on state coercion and local resistance—common in political ecology—the biofuel expansion relied, in this case, upon a ‘politics of consent’ in which both the state and rural organisations, albeit in a power-laden relationship, sought to achieve their own goals by supporting the planting of biofuel crops. These findings suggest the need to rethink how particular approaches within political ecology apply Gramsci's notions of power and hegemony and, more broadly, to consider the importance of politics in explaining why certain forms of agricultural production become dominant.
    Collective action in a smallholder oil palm production system in Indonesia: The key to sustainable and inclusive smallholder palm oil?
    Jelsma, Idsert ; Slingerland, Maja ; Giller, Ken E. ; Bijman, Jos - \ 2017
    Journal of Rural Studies 54 (2017). - ISSN 0743-0167 - p. 198 - 210.
    Collective action - Indonesia - Intensive agriculture - Oil palm - Smallholders - West-Sumatra
    Indonesian smallholder oil palm generally yield much less than corporate plantations. We analysed a smallholder oil palm production system in West Sumatra which outperformed its nucleus estate plantation, consistently producing yields far above the national average for over 25 years. Its institutional setup allowed farmers to combine the advantages of smallholder and plantation agriculture by capitalizing on collective action. Collective action design principles (Ostrom, 1990; Cox, 2010) are used to assess the institutional setup of a smallholder production system. This case study demonstrates that with a strong institutional arrangement, smallholder oil palm farmers can participate in supply chains on advantageous conditions and substantially increase productivity, thereby contributing to both rural development and land sparing.
    Hydrological and economic effects of oil palm cultivation in Indonesian peatlands
    Sumarga, Elham ; Hein, Lars ; Hooijer, Aljosja ; Vernimmen, Ronald - \ 2016
    Ecology and Society 21 (2016)2. - ISSN 1708-3087
    Ecosystem services - Flood risk modeling - Indonesia - Jelutung - Oil palm - Peat

    Oil palm has increasingly been established on peatlands throughout Indonesia. One of the concerns is that the drainage required for cultivating oil palm in peatlands leads to soil subsidence, potentially increasing future flood risks. This study analyzes the hydrological and economic effects of oil palm production in a peat landscape in Central Kalimantan. We examine two land use scenarios, one involving conversion of the complete landscape including a large peat area to oil palm plantations, and another involving mixed land use including oil palm plantations, jelutung (jungle rubber; (Dyera spp.) plantations, and natural forest. The hydrological effect was analyzed through flood risk modeling using a high-resolution digital elevation model. For the economic analysis, we analyzed four ecosystem services: oil palm production, jelutung production, carbon sequestration, and orangutan habitat. This study shows that after 100 years, in the oil palm scenario, about 67% of peat in the study area will be subject to regular flooding. The flood-prone area will be unsuitable for oil palm and other crops requiring drained soils. The oil palm scenario is the most profitable only in the short term and when the externalities of oil palm production, i.e., the costs of CO2emissions, are not considered. In the examined scenarios, the social costs of carbon emissions exceed the private benefits from oil palm plantations in peat. Depending upon the local hydrology, income from jelutung, which can sustainably be grown in undrained conditions and does not lead to soil subsidence, outweighs that from oil palm after several decades. These findings illustrate the trade-offs faced at present in Indonesian peatland management and point to economic advantages of an approach that involves expansion of oil palm on mineral lands while conserving natural peat forests and using degraded peat for crops that do not require drainage.

    Embedding research for innovation to meet societal needs in national research systems : Experiences from Ghana
    Osei-Amponsah, Charity ; Sakyi-Dawson, Owuraku ; Adjei-Nsiah, Samuel ; Adu-Acheampong, Richard ; Essegbey, George ; Quarmine, William - \ 2016
    Cahiers Agricultures 25 (2016)6. - ISSN 1777-5949
    Cocoa - Cross-scale agricultural transformations - Ghana - Innovation platforms - Institutional innovation - Oil palm

    The experiences synthesised in this article indicate how significant effects in two agricultural domains have been achieved by creating pathways for inter-dependent socio-technical and institutional changes, at a range of levels of action, governance and policy-making. The synthesis emphasizes the importance of co-learning, experimentation, and critical reflection among a wide network of 'champions' of transformational change on behalf of smallholder farmers and processors. It shows that innovation processes may involve actors along entire value chains, industry leaders at national level, or local level actors seeking to widen the space for change beyond their immediate circle of direct influence. While the research and development initiatives of the domains are shown to have been critical in identifying the constraints and opportunities of smallholders, and also to the effects documented, this was largely because the research effort converged around empirically grounded problems and opportunities identified. The information sought, and the solutions found useful, were determined by the members of innovation platforms that drove the processes of change.

    Delignification outperforms alkaline extraction for xylan fingerprinting of oil palm empty fruit bunch
    Murciano Martínez, Patricia ; Kabel, Mirjam A. ; Gruppen, Harry - \ 2016
    Carbohydrate Polymers 153 (2016). - ISSN 0144-8617 - p. 356 - 363.
    Delignification - Enzymes - Oil palm - Sequential extraction - Xylan

    Enzyme hydrolysed (hemi-)celluloses from oil palm empty fruit bunches (EFBs) are a source for production of bio-fuels or chemicals. In this study, after either peracetic acid delignification or alkaline extraction, EFB hemicellulose structures were described, aided by xylanase hydrolysis. Delignification of EFB facilitated the hydrolysis of EFB-xylan by a pure endo-β-1,4-xylanase. Up to 91% (w/w) of the non-extracted xylan in the delignified EFB was hydrolysed compared to less than 4% (w/w) of that in untreated EFB. Alkaline extraction of EFB, without prior delignification, yielded only 50% of the xylan. The xylan obtained was hydrolysed only for 40% by the endo-xylanase used. Hence, delignification alone outperformed alkaline extraction as pretreatment for enzymatic fingerprinting of EFB xylans. From the analysis of the oligosaccharide-fingerprint of the delignified endo-xylanase hydrolysed EFB xylan, the structure was proposed as acetylated 4-O-methylglucuronoarabinoxylan.

    The introduction of oil palm in Northeast Thailand: a new cash crop for smallholders?
    Somnuek, Siriluk ; Slingerland, M.A. ; Grünbühel, C.M. - \ 2016
    Asia Pacific Viewpoint 57 (2016)1. - ISSN 1360-7456 - p. 76 - 90.
    Oil palm - self-sufficiency - Diversity of income - Farmer’s livelihood - Northeast Thailand
    As part of the Thai Government’s objective to increase energy security through biodiesel, oil palm was introduced to Northeast Thailand in 2005. Nong Khai Province was selected as a pilot project because of its suitable environmental conditions. This study assesses the acceptance of policy interventions and socio-economic conditions by adopters and non-adopters. We found that total farmland size was significantly higher among oil palm producers than among non-producers. Nevertheless, the area under oil palm cultivation did not increase in accordance with land size in the way rubber did. Oil palm and non-oil palm farmers had almost equal amounts of rice area thereby providing household food security. Oil palm did not replace food crops. Farmers investing in oil palm tend to base their livelihood around on-farm production, whereas non-adopters tend to diversify with off-farm income sources. Oil palm was found to be one component of a diversified farming system and an additional income source, albeit not the primary one. In conclusion, oil palm was a crop that had been tried by (wealthier) farmers with sufficient capital, and an aim to further diversify on-farm household income. Oil palm is certainly not (yet) contributing substantially to household income in Thailand’s Northeast.
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