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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.

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Physiological responses of rice to increased day and night temperatures
Shi, Wanju - \ 2017
Wageningen University. Promotor(en): P.C. Struik, co-promotor(en): X. Yin; K.S.V. Jagadisch. - Wageningen : Wageningen University - ISBN 9789463437110 - 202
crops - rice - oryza sativa - plant physiology - temperature - crop yield - grain - agronomy - gewassen - rijst - oryza sativa - plantenfysiologie - temperatuur - gewasopbrengst - graan - agronomie

A more rapid increase in night-time temperature compared with day-time temperature and the increased frequency of heat waves associated with climate change present a serious threat to rice (Oryza sativa L.) production and food security. This thesis aims to understand the impact of high night-time temperature (HNT) and high day-time temperature (HDT) on rice grain yield and grain quality and to examine adaptation strategies to cope with high-temperature stresses.

Grain yield and quality of a susceptible indica genotype (Gharib) and all tested hybrids, when exposed to HNT in the field, were significantly reduced across seasons, with less average reduction in the dry season than in the wet season, indicating that other environmental factors under field conditions may contribute to impacts of HNT on yield. Among the different yield components, a reduced number of spikelets m−2 significantly contributed to yield loss under HNT followed by the consistently lower single-grain weight across all genotypes, while the impact of the decrease in percentage seed-set was less and season-specific. Lower grain yield and poorer grain quality in susceptible cultivar Gharib were associated with a significant reduction in non-structural carbohydrate translocation after flowering, resulting in reduced grain-filling duration. Increased total nitrogen application did not alleviate the negative impact of HNT. The proposed model approach showed that there were significant differences among cultivars in their changes in source-sink relationships in response to HNT. Given that rice grain yield and quality are challenged by a rise in HDT and HNT, in particular at flowering and during grain filling, differential impacts of HNT and HDT during these critical stages were observed. For the single-grain growth during grain filling, HDT either independently or in combination with HNT exerted greater influences than HNT on the grain filling dynamics, activities of starch metabolism enzymes, temporal starch accumulation patterns, and the process of chalk formation. During flowering, HDT increased spikelet sterility in tested hybrids and hybrids were less tolerant to high temperatures than high-yielding inbred varieties. Moreover, in contrast with HNT, HDT played a dominant role in determining spikelet fertility. Novel observations with a series of snapshots of dynamic fertilization processes demonstrated that disturbances in the pre-fertilization phase were the primary causes for heat-induced spikelet sterility, indicating the effectiveness of employing the early-morning flowering trait for mitigating the impact of heat stress at flowering on rice.

Agronomic and environmental studies of potato (Solanum tuberosum L.) and analysis of its value chain in Zimbabwe
Svubure, O. - \ 2015
Wageningen University. Promotor(en): Paul Struik; Anton Haverkort, co-promotor(en): J.M. Steyn. - Wageningen : Wageningen University - ISBN 9789462575646 - 220
solanum tuberosum - aardappelen - waardeketenanalyse - voedselzekerheid - duurzaamheid (sustainability) - gebruiksefficiëntie - modellen - agronomie - akkerbouw - zimbabwe - solanum tuberosum - potatoes - value chain analysis - food security - sustainability - use efficiency - models - agronomy - arable farming - zimbabwe

Keywords: Irish potato, food security, stakeholder analysis, sustainability indicators, Cool Farm Tool-Potato, yield gap, resource use efficiency, LINTUL-POTATO model, Zimbabwe.

Oniward Svubure (2015). Agronomic and environmental studies of potato (Solanum tuberosum L.) and analysis of its value chain in Zimbabwe. PhD thesis, Wageningen University, The Netherlands, with English summary, 220 pp.

Irish potato is food for more than a billion people worldwide. In Zimbabwe, Irish potato is becoming an important food crop. The government declared it a national strategic food security crop on 18 May 2012. This major policy pronouncement, qualified Irish potato for government initiated farmer support initiatives such as mechanisation and irrigation capacity building. The growing importance of potato as a food crop is prefaced on rising food insecurity in the country coupled with the impact of the radical land reform of 2000 on agricultural production. The land reform completely restructured commercial agriculture when about 96 % of the original 12.5 million ha of large-scale commercial farmland in 1980 was taken up for resettlement by 2010. Two resettlement models were used, the A1 and A2 resettlement models. The former resembles the communal area land allocation system while the later are self-contained small to medium scale farm units ranging about 35 to 300 ha. The newly resettled farmers have started growing potato adding to the already existing communal area and the few remaining large-scale commercial farmers. It is in this context that the potential of the new agrarian structure to sustainably increase Irish potato production was investigated. Increasing potato production on a sustainable basis will enable the crop to assert itself as a national strategic food security crop and help ease the food security challenges the country is grappling with. A grower survey was conducted on the cultural practices, input use, average yield, and infrastructure for potato production. The survey data was used to categorise the growers. Only growers with a minimum 5 years continuous potato growing experience were targeted making the data collected dependable. Grower resource footprints of land, water, biocides and nutrients were calculated based on the actual yield, Ya. Further, the Ya data collected were used to calculate the yield gap, YG, based on the yield of the best performing growers, Yh, simulated yield potential, Yp, and water-limited potential yield, Yw, of the respective agro-ecological areas. The LINTUL-POTATO model was used to estimate Yp, Yw and water need. This model simulates potential dry matter production based on radiation use efficiency of intercepted light by the potato crop. Another model, the Cool Farm Tool-Potato was used to further distinguish and appraise the production systems in terms of yields, inputs and efficient use of energy as reflected in their CO2 balances. The model calculates the contributions of various production operations to the total greenhouse gas (GHG) emission. Consequently, grower practices which contribute the most to the GHG emission were identified and generic mitigation measures for each production system were suggested. Realising the growing importance of sustainability issues in agricultural production and the scarcity of evaluation protocols in cropping systems, the study developed a framework that can be used to evaluate cropping systems. The framework was constructed using the potato-based cropping systems in the Eastern Highlands of Zimbabwe. Finally, instead of just focusing on the production related aspects only, the study also took into cognisance the need to understand the performance of the entire Irish potato sector in Zimbabwe. A value-chain analysis was therefore conducted to evaluate the performance the Irish potato sector in the country. Irish potato production in Zimbabwe is still low. Experts estimate annual production at nearly 120,000 t from around 6,000 ha. The large-scale commercial and the A2 resettlement are large-scale, high input and mechanised systems with an average potato area of 9 ha per planting. The communal area and A1 resettlement are smallholder low input systems with average potato area per planting of 0.8 ha and animal-drawn equipment is used. On resource use efficiencies, the actual tuber yield ranged from 8 – 35 t/ha across all systems representing a yield gap of over 77 %. Comparing with the simulated average potential yield, the mean actual yield observed ranged from 8 to 35 % of the simulated potential yield, translating to a yield gap of 65 to 92 %. Hence there is a large potential to increase potato production in these environments. The nutrient use efficiencies range were: 97 to 162 g potato g-1 N, 93–105 g potato g-1 P2O5 and 97–123 g potato g-1 K2O. This was anticipated because of the high synthetic fertiliser use and the low actual yields reported. The biocide use efficiencies ranged from 0.5 to 0.9 kg potato g-1 active ingredient (a.i.) fungicide, and 8 to 15 kg potato g-1 a.i. insecticide. Regarding water use, the average water use efficiency based on irrigation water and rainfall, ranged from 2 to 6 g potato l-1, while the simulated potential water use efficiency from irrigation and precipitation ranged from 9 to 17 g potato l-1. The large gap observed between actual and potential water use efficiency shows the scope to improve crop management practices to increase actual yield while lowering irrigation water. On the CO2 balance of the systems, a high carbon footprint was reported with an average of 251 kg CO2 eq./t potato. The least average carbon footprint was 216 kg CO2 eq./t potato for the communal area, while the A2 resettlement system had the highest of 286 kg CO2 eq./t potato. The high carbon footprint was anticipated as a reflection of the systems’ inefficiencies in terms of low yields and high input use. Focussing on the performance of the entire Irish potato sector, value chain analysis showed considerable levels of value-addition and gross profit of at least 13 % at each linkage. While the sector enjoys government policy support, major factors impacting on the value-chain performance relate to high potato production costs, low yields, and lack of farmer training. On the proposed framework on cropping sustainability, the indicator thresholds serve to monitor farmer progress as they improve their practices towards the desired direction of sustainability. This study demonstrated that there is tremendous potential to increase potato output and help ease the food insecurity challenges the country currently faces.

Epilogue: global food security, rhetoric, and the sustainable intensification debate
Kuijper, T.W.M. ; Struik, P.C. - \ 2014
Current Opinion in Environmental Sustainability 8 (2014). - ISSN 1877-3435 - p. 71 - 79.
green-revolution - agricultural intensification - ecological intensification - 9 billion - systems - agroecology - challenges - opportunities - perspective - agronomy
The need to feed nine billion people in 2050 has given rise to widespread debate in science and policy circles. The debate is largely framed in neo-Malthusian terms, and elements of global food security (resilience of the food system, food quantity and quality, right to and access to food) demand equal attention. High-intensive agriculture, which enabled population growth and food for a large proportion of the global population, is often regarded as incompatible with current environmental (and social) sustainability. Because of the often problematic nature of high-intensive industrialized agriculture, sustainable agricultural intensification has been called an oxymoron. Pathways to sustainably intensify agriculture vary from business-as-usual to claims that a radical rethinking of our agricultural production is imperative. Three terms have been coined to differentiate such pathways. Whereas conventional intensification, that is business-as-usual, is uncontroversial (but often considered unlikely to be able to achieve environmental sustainability), the phrases sustainable intensification and ecological intensification both have a complex history. Although one could think that they have similar meanings, the phrases represent very different perspectives in discourses in science and policy circles. The terms Utopians and Arcadians are introduced for adherents of those perspectives. We observe that they both devote insufficient attention to inevitable trade-offs. Agricultural intensification in developing countries was greatly accelerated by the Green Revolution, which largely bypassed sub-Saharan Africa. Discontent with that outcome has led to a plethora of new terms to indicate more successful next steps for sub-Saharan agriculture. Industrialized agriculture as currently practised in developed countries will not provide a universal solution. This epilogue of the special issue and the literature herein show that intense debates on sustainable agricultural intensification are needed. Such debates on intensification demand reflection on the role of scientists with regard to their uses of current and the generation of novel knowledge.
Exploration of agro-ecological options for improving maize-based farming systems in Costa Chica, Guerrero, Mexico
Flores Sanchez, D. - \ 2013
Wageningen University. Promotor(en): Martin Kropff, co-promotor(en): Walter Rossing; Egbert Lantinga. - S.l. : s.n. - ISBN 9789461736758 - 205
bedrijfssystemen - maïs - zea mays - agro-ecologie - agro-ecosystemen - agronomie - intensivering - tussenteelt - mexico - farming systems - maize - zea mays - agroecology - agroecosystems - agronomy - intensification - intercropping - mexico

Keywords: farm diagnosis, farming systems, soil degradation, intercropping, maize, roselle, legumes, nutrient management, vermicompost, crop residues, decomposition, explorations.

In the Costa Chica, a region of Southwest Mexico, farming systems are organized in smallholder units. The dominant cropping systems are based on maize (Zea mays L.), either as monocrop or intercropped with roselle (Hibiscus sabdariffa L.). Continuous cropping, and unbalanced fertilizer management systems with an inadequate replenishment of organic matter stocks have caused depletion of soil fertility and low crop yields. This thesis aimed to evaluate alternative cropping systems in terms of their contribution to on-farm productivity and to regeneration of the soil resource base. A set of approaches including farm surveys, on-farm experiments and model-based calculations was applied to characterize farming systems, identify main livelihood constraints and evaluate alternative cropping and farming systems. Main constraints identified were low yields of the major crops maize and roselle, low levels of nitrogen, potassium and soil organic matter, low resource use efficiencies, high production costs, limited marketing opportunities and low prices of products. To address prevailing production constraints, farmer-managed experiments were established in two communities within the region. In on-farm experiments the legumes Canavalia (Canavalia brasiliensis Mart. Ex Benth) and Mucuna (Mucuna pruriens L.var. utilis (Wall ex Wight) Burk) were intercropped in (added to) maize monocrops and maize-roselle mixtures. Intercropping did not decrease maize and roselle yields, and resulted in major reductions of the weed biomass, as well as an increased N uptake by both the food crops and the cropping system as a whole. In nutrient management trials different sources of macro-nutrients were evaluated in maize monocrops and maize-roselle intercrops. The results showed that improvements at field scale are feasible in the short term. Partial replacement of mineral NPK by organic NPK in the form of vermicompost, leading to 10-20% lower total N and K inputs, did not result in lower maize yields or a reduced uptake of N and K. This suggests that the N and K from the vermicompost were utilized better by the maize crop than from the inorganic fertilizers due to lower leaching losses. An experiment on decomposition of and N release from aboveground biomass residues, crop root residues and vermicompost demonstrated that, although the pattern of decomposition varied depending on the type of organic material, most of the N was released within the cropping season. Particularly for vermicompost, only one third of its initial dry mass was decomposed, thus leaving significant amounts of residues for soil organic matter build-up. Model-based explorations were developed to assess the consequences of the experimental results at the field level for whole-farm performance. Results for eight case study farms demonstrated that changes in crop nutrition and animal husbandry can increase farm family income and improve organic matter balances. However, strategies to achieve these goals most effectively were distinct. To maximize family income required fertilizer-based cropping strategies, while rebuilding soil organic matter required investment in retaining, obtaining and applying sources of organic matter. Farms responded differently to the explored options, highlighting the need for crop nutrition strategies that are adjusted to the soil fertility status of individual fields to be most efficient. The explorations also showed that for six out of the eight farms the minimum family income standard could not be attained. The results imply that the current emphasis in policies to support smallholders by fertilizer subsidies requires adjustment to include promotion of technology development aimed at regeneration of the degraded resource base and to offer off-farm economic options.

Analysis of constraints for compliance to Good Agricultural Practices by the horticultural sector in Indonesia : project report 2011
Koomen, I. ; Zulkarnain, I. ; Suleaman, A. ; Ruting, A. - \ 2012
Wageningen : Wageningen UR Centre for Development Innovation - 43
good practices - agronomie - landbouwplantenteelt - voedselveiligheid - certificering - tuinbouwgewassen - indonesië - agronomy - crop husbandry - food safety - certification - horticultural crops - indonesia
The horticultural industry in Indonesia is progressively moving to apply Good Agricultural Practices (GAP) with the aim of producing sustainably as well as guaranteeing food safety. While the Ministry of Agriculture has put a lot of effort in assisting farmers to comply to the national IndoGAP and become Si Sakti certified uptake has been slower than expected. This study has tried to identify the constraints for compliance to GAP such that with this knowledge incentives for GAP compliance can be formulated.
Future harvest : the fine line between myopia and utopia
Ittersum, M.K. van - \ 2011
Wageningen : Wageningen University - ISBN 9789085858911 - 32
agronomie - landbouwproductie - voedselproductie - toekomst - agronomy - agricultural production - food production - future
Inaugural lecture upon taking up the post fo Personal Professor of Plant Production Systems at Wageningen University on 12 May 2011.
Jatropha Assessment. Agronomy, socio-economic issues, and ecology. Facts from literature.
Eijck, J.A.J. van; Smeets, E. ; Romijn, H.A. ; Balkema, A.J. ; Jongschaap, R.E.E. - \ 2010
Utrecht, the Netherlands : NL Agency (Report NL Agency, November 2010 ) - 157
jatropha - agronomie - sociale economie - duurzaamheid (sustainability) - voedselzekerheid - haalbaarheidsstudies - biobased economy - jatropha - agronomy - socioeconomics - sustainability - food security - feasibility studies - biobased economy
Jatropha (Jatropha curcas L.) has been promoted as a potential renewable energy source for many of its advantageous properties in comparison to other biomass feedstock. This report summarises the agronomy, socio-economic issues, and ecology facts from literature on Jatropha. Such an overview is essential to formulate recommendations and policy guidelines to stimulate best project practices and also help to avoid the promotion of unviable or unsustainable practices.
Evaluation of agronomic practices for mitigation of natural toxins
Speijers, G. ; Alink, G.M. ; Saeger, S. de; Hardy, A. ; Magan, N. ; Pilegaard, K. ; Battilani, P. ; Riemens, M.M. - \ 2010
Brussel : ILSI Europe, International Life Sciences Institute (ILSI Europe report series ) - ISBN 9789078637226 - 48
agronomie - natuurlijke toxinen - mitigatie - mycotoxinen - risicoschatting - agronomy - natural toxins - mitigation - mycotoxins - risk assessment
Management practices and opportunities in the East African highland banana (Musa AAA-EA) production in Uganda
Wairegi, L. - \ 2010
Wageningen University. Promotor(en): Ken Giller, co-promotor(en): P.J.A. van Asten; M.A. Bekunda. - [S.l. : S.n. - ISBN 9789085857884 - 155
musa - bananen - agronomie - landbouwplantenteelt - gewasopbrengst - mestbehoeftebepaling - bodemvruchtbaarheid - kunstmeststoffen - mulchen - hooglanden - uganda - musa - bananas - agronomy - crop husbandry - crop yield - fertilizer requirement determination - soil fertility - fertilizers - mulching - highlands - uganda
Sustainable potato production: guidelines for developing countries
Lutaladio, N. ; Ortiz, O. ; Haverkort, A.J. ; Caldiz, D.O. - \ 2009
Rome : FAO - ISBN 9789251064092 - 94
solanum tuberosum - aardappelen - gewasproductie - agronomie - landbouwplantenteelt - plantenziektekunde - duurzaamheid (sustainability) - ontwikkelingslanden - tropen - subtropen - potatoes - crop production - agronomy - crop husbandry - plant pathology - sustainability - developing countries - tropics - subtropics
During the International Year of the Potato, celebrated in 2008, FAO and CIP helped forge partnerships worldwide to address critical aspects of sustainable potato production. This technical guide collates that experience to review technical, socio-economic, policy and institutional factors that currently constrain increased potato production and productivity in tropical and subtropical countries. It presents Good Agriculture Practices relevant to potato production, and indicators and recommendations for action in key areas, from the utilization of potato biodiversity and improvements in seed systems, to soil management, insect pest and disease control and opportunities for value addition. It outlines a new policy and research agenda for the potato subsector that aims at making a real contribution to the eradication of hunger and poverty.
Nulmeting emissie broeikasgassen Gelderse land- en tuinbouw
Lesschen, J.P. ; Kuikman, P.J. ; Wyngaert, I.J.J. van den - \ 2009
Wageningen : Alterra (Alterra-rapport 1891) - 58
klimaatverandering - broeikaseffect - broeikasgassen - emissie - agronomie - landbouwsector - meting - nederland - regionaal bestuur - maatregelen - gelderland - climatic change - greenhouse effect - greenhouse gases - emission - agronomy - agricultural sector - measurement - netherlands - regional government - measures
Het doel van deze nulmeting is het kwantificeren en het ruimterlijk in beeld brengen van de broeikasgasemissie uit de Gelderse land- en tuinbouw en het landgebruik bos voor de jaren 1990 (referentiejaar voor Kyoto) en 2005. De informatie is uitgesplitst voor de verschillende agrosectoren (melkveehouderij, vleesveehouderij, vleeskalverhouderij, varkenshouderij, pluimveehouderij, overige veehouderij, akkerbouw en vollegrondstuinbouw en glastuinbouw). Op basis van deze uitkomsten wordt een trendanalyse gerapporteerd van de te verwachten emisies en er worden een aantal emissiebeperkende maatregelen doorberekend voor de drie agrosectoren met de hoogste broeikasgasemissie
Cassava and soil fertility in intensifying smallholder farming systems of East Africa
Fermont, A.M. van - \ 2009
Wageningen University. Promotor(en): Ken Giller, co-promotor(en): Mark van Wijk; Pablo Tittonell. - [S.l. : S.n. - ISBN 9789085853992 - 196
manihot esculenta - cassave - bodemvruchtbaarheid - agronomie - bedrijfssystemen - systeemanalyse - voedselzekerheid - kunstmeststoffen - kenya - uganda - manihot esculenta - cassava - soil fertility - agronomy - farming systems - systems analysis - food security - fertilizers - kenya - uganda
Keywords: Cost-benefits, Crop management, Farming systems, Fertilizer, Food security, Generalizations, Income, Labour, Land pressure, Niche, Rainfall, Sub-Saharan Africa, System analysis, Yield gap.
Cassava is an important crop in Africa. This thesis focuses on cassava production in the mid altitude zone of East Africa, an area characterized by high population densities, bimodal rainfall patterns and relatively poor soils. The overall aim was to better understand the roles and production constraints of cassava in order to explore opportunities to improve the productivity and sustainability of intensifying cassava-based smallholder farming systems in East Africa. Increasing land pressure has changed agricultural landscapes from traditional millet-, cotton-, sugarcane- or banana-based systems with an important fallow component to continuously, cultivated cassava-based systems. Cassava cultivation on cropped fields increased from 1-11 to 16-55% in three to four decades as farmers believe that cassava improves soil fertility for the subsequent crop and increasingly target cassava to low fertility soils when land pressure increases. The substantial increase in cassava cultivation has allowed farmers to postpone intensification of crop management, but it seems that the elasticity of the traditionally low-input systems is coming to an end as production of the two most important crops (cassava and maize) is limited by nutrients. Farmers in areas of high land pressure have started to adopt fertilizer and manure and to improve crop management.
Contrary to existing generalizations, cassava is not a food security crop for poorer farmers in East Africa, but an important food and cash crop for farmers from all wealth classes. Average farm income was not less than in other farming systems in the region, while average food security was higher (>10 months year-1) than in maize-based systems. Cassava is also not predominantly grown as an intercrop, as is often thought, nor is it grown without inputs, because farmers commonly use hired labour and improved genotypes. In addition, its labour requirements are higher than commonly assumed (287 man days ha-1), due to large requirements for weed control. Existing generalizations concerning cassava are therefore either false or half truths and a continued belief in them will hamper the effectiveness of policy and development efforts aimed at improving cassava production. Efforts to increase cassava production in cassava-based farming systems will, for example, improve its scope for commercialization, but will not significantly enhance food security.
Average farmer yields for cassava (7-12 t ha-1) are far below attainable yields on farm (30-50 t ha-1). Still, on-farm yields are highly variable. Largest yields were obtained on farms with high labour availability, fertile soils, good weed management and timely (not too early) harvesting. An improved technology package more than doubled
average yields in farmer fields, whereby the largest yield increase for a single technology was observed with 100-22-83 kg ha-1 N-P-K fertilizer. Multivariate analysis identified soil fertility, rainfall and weed management as the most important production constraints, while biotic factors were less important. Many fields were affected by multiple and interacting production constraints. Fertilizer responses were governed by the same, interacting factors influencing unfertilized cassava production. Genotype and biotic factors did not influence fertilizer response. Closing the considerable yield gap between actual and attainable cassava yields at farm level, can not be achieved by integrated pest management and breeding alone. Instead, research and development organizations should focus on addressing the whole range of interacting production constraints through the development and evaluation of integrated management packages. Improving cassava production will be more difficult for poorer than for wealthier farmers, as the first have less social and financial capital and less fertile soils and are therefore more likely to face multiple production constraints.
The positive impact of cassava on soil fertility perceived by farmers is supported by model simulations and nutrient balances that indicate that cassava may improve SOC contents of low fertility soils compared with maize and contribute to higher N recycling through crop residues. Adoption of higher yielding genotypes and improved production practices will improve yields and increase nutrient removal rates, but may simultaneously have a positive effect on SOC contents and nutrient recycling rates. Improving cassava stem management after harvesting seems an interesting option to improve sustainability of the system.
This thesis concludes that there is an urgent need to invest in agronomy and ISFM research and to reform existing research for developments programmes with a strong emphasis on breeding and IPM into integrated programmes that are able to address the multiple production constraints of cassava and thereby significantly contribute to improving the livelihoods of smallholder cassava farmers.

Growth and development of true sago palm (Metroxylon sagu Rottbøll) : with special reference to accumulation of starch in the trunk : a study on morphology, genetic variation and ecophysiology, and their implications for cultivation
Schuiling, D.L. - \ 2009
Wageningen University. Promotor(en): Paul Struik. - [S.l.] : S.n. - ISBN 9789085858546 - 259
metroxylon sagu - sago - arecaceae - starch crops - plant development - growth analysis - plant morphology - agronomy - maluku - indonesia - ecophysiology - economic botany - metroxylon sagu - sago - arecaceae - zetmeelgewassen - plantenontwikkeling - groeianalyse - plantenmorfologie - agronomie - molukken - indonesië - ecofysiologie - economische botanie
Keywords: Metroxylon sagu, Arecaceae, starch crops, plant growth and development, plant morphology, inflorescence structure, electron microscopy, phenological scale, genetic variation, plant taxonomy, folk taxonomy, ethnobotany, leaf area, leaf area index, starch accumulation, starch distribution, plant ecophysiology, tropical lowlands, wetlands, traditional processing, estate cultivation, agronomy, Moluccas, Maluku.

True sago palm (Metroxylon sagu Rottbøll) is a stout, clustering palm adapted to swampy tropical lowland conditions. Each axis in a sago palm clump flowers once at the end of its life after having amassed a large amount of starch in its trunk. Man can harvest this starch by felling the trunk, pulverizing the pith and leaching the starch out with water, and use it like other starches for food or non-food purposes. It is a staple food mainly in eastern Indonesia and in Papua New Guinea where it is harvested mostly from semi-managed stands. For establishing sago palm as a full-fledged plantation crop, desirable because of its envisaged large yield potential as a perennial, its niche habitat, and its potential as a raw material provider for bio-ethanol production, the scientific base for establishing the right felling time to harvest the starch needed strengthening.

Between October 1988 and November 1990, 27 sago trunks in the Adult Vegetative (AV) or Generative (G) phase belonging to six varieties were selected from semi wild sago stands in the Moluccas, eastern Indonesia: 23 trunks (4 varieties) on the alluvial coastal plain near Hatusua village, Seram Island, and 4 trunks (2 varieties) on hilly terrain near Siri Sori Serani village, Saparua Island. These trunks were felled, dissected, morphologically described and sampled for the amount and distribution of starch they contained. The leafless parts of the trunks were 4.45 to 19.65 m long, had a mean starch density of 4.6 to 254 kg/m3 and contained five to 777 kg of starch (maximum found in a whole trunk: 819 kg).

To link starch content to age, the ages of the sampled trunks had to be estimated. To enable age estimation by counting leaf scars on the trunk, the leaf unfolding rate of 36 AV-phase palms around Hatusua (31 palms) and Siri-Sori Serani (5 palms) was monitored for varying periods between 1989 and 1992. Probably due to large variation in habitat and genetic make up, this rate varied from 2 to 14 leaves per year (mean 7.85), rendering number of leaf scars unfit as accurate age estimator. Also trunk height proved unfit for this purpose. From monitoring 5 G-phase palms, the G-phase could be subdivided into 3 sub-phases (G1, G2, G3), recognizable from the ground by the phased development of the successive orders of inflorescence branches. By combining gathered morphological and monitoring data, a phenological scale of a model palm was composed consisting of two parallel timelines of hidden and outwardly visible events: two years after the start of the Establishment (E) phase, the first AV-phase leaf is initiated in the apical growing point, to unfold only 2.5 years later; the initiation of the first AV-phase tissues is followed 12.5 to 14.5 years later by the initiation of the first G-phase tissues, followed 4 to 5.5 years later by the shedding of fruits, and finally by a 2- to 5-year Recycling phase (name proposed here) in which the axis decays and collapses. This scale, which accounts for the large time gap between initiation of trunk parts and their becoming visible, may help to correctly time cultural measures. The 27 sampled trunks could tentatively be ranked according to physiological age into 4 AV phase classes and 9 G phase classes.

Since the examined palms belonged to 6 different local varieties, their relative rareness or commonness had to be established to assess the validity of the findings. Based on literature and on interviews with informants, an overview of locally recognised sago palm varieties is presented. The number of unique variety names in 32 localities in Indonesia and Papua New Guinea totalled 325, ranging from 2 (spined vs unspined only) to 34 per locality. On the basis of this survey, the Hatusua varieties were considered average. The nomenclatural category folk variety (fovar, fv.) is proposed to unambiguously name local varieties by adding to the variety name an indication of the location where, and (if known) the ethnic/linguistic group by which that name is used.


Leaf area estimation methods were devised to enable investigation of the relationship between leaf area and starch content. In the AV-phase the Total leaf area (TLA) of a sago palm axis ranged from 200 m2 to 325 m2, one axis having an exceptional TLA of 388 m2. The TLA in the G-phase before fruiting mostly remained within the same range, possibly exceeding it for a short period early in that stage. The Leaf area index (LAI) of an individual axis showed an upward trend from 1 - 1.5 in the E-phase to 1.25 - 1.75 in the AV-phase, to more than 2 in the early G-phase, followed by a decrease to about 1.5 again in the late G-phase before fruiting. No fruiting palms were available for analysis. The TLA and LAI of a single trunk could not be linked to the mean starch density of its pith, nor to the total amount of starch the pith contained.
Generally, starch density in the trunk first increased with height above ground level, reached a maximum about half-way to two-thirds up the leafless part of the trunk, and then sharply dropped towards the top of the trunk. From the late AV phase onward the maximum starch density ranged from 238 to 284 kg/m3. The four trunks with the highest maximum starch densities, all closely around 280 kg/m3, belonged to three different varieties, suggesting that 280 kg/m3 may be considered the maximum starch storage capacity in the pith of any variety.
The starch distribution pattern in the leafless part of the trunk showed a tendency to evolve with age from two tailed (density gradually increasing from base, gradually decreasing towards top) to one tailed (density gradually increasing from base, sharply decreasing towards top). The differences in distribution pattern found strongly suggested that there must be other factors besides age and development phase affecting starch accumulation. Attempts to determine the effect of palm variety and of the environment mostly failed.

Potential yield of a model palm based on the maximum starch density of 280 kg/m3 was estimated at 840 kg of dry starch. That this amount is much higher than generally found may partly be due to poor recovery ratios, as the results of a traditionally processed trunk demonstrated: only 47% of the starch in the processed trunk part was recovered, and if the unharvested starch present in the traditionally discarded basal and top part of the trunk is taken into account, recovery drops to 44%.

In an attempt to establish the point in time at which a sago palm starts to be a nett consumer of its own starch, the course of the energy producing and consuming capacity of an axis during its life time was modelled based on the assumption that by the end of the AV-phase the existing TLA of the axis produces just the amount of energy needed to maintain existing biomass, to keep up the normal regular growth, and to fill new trunk with starch. Using this model, assimilate requirements for building and maintaining the inflorescence and the fruits could not be met by the production capacity of the leaves plus the starch reserves in the trunk. For this modelling approach to succeed in predicting the turning point from nett production to nett consumption of starch by a sago palm axis, additional data on chemical composition of its parts and on assimilation rate are needed.

Lack of precise data on the age of the sampled trunks and lack of uniformity of their genetic make up and growing conditions made it impossible to arrive at the sought-after detailed timetable of the evolution of trunk starch accumulation and depletion to base the right felling time of a sago palm on. The high starch density found in the trunk of a palm with half-grown fruits indicated that depletion of starch reserves by the palm itself may set in much later than generally assumed.
Once the course of starch accumulation in time in a single axis is unravelled, the next research question should be how this adds up in a clump - the actual production unit in a plantation - with axes of different age. Timing felling in such a situation should be aimed at maintaining a maximum starch accumulation rate for the plantation as a whole rather than at harvesting a maximum amount of starch per trunk.

Data sheets of each palm examined containing all primary and some secondary data, and including photographs, are appended in digital form.


Guide to cultivated plants
Elzebroek, A.T.G. ; Wind, K. - \ 2008
Wallingford : CABI - ISBN 9781845933562 - 540
gewassen - planten - plantkunde - agronomie - landbouwplantenteelt - economische botanie - agro-ecologie - crops - plants - botany - agronomy - crop husbandry - economic botany - agroecology
Guide to cultivated plants includes concise textual descriptions and attractive full color illustrations of over 300 crop species. These comprise 11 commodity groups ranging from vegetables, both horticulture and forages species, and arable crops to the major fruits and plantation crops. All major cultivated plants from temperate, Mediterranean and tropical climates are covered and the morphology, botany, ecology, agronomy and use of cultivated crops is fully discussed.
Studies on agronomy and crop physiology of Plectranthus edulis (Vatke) Agnew
Taye, M. - \ 2008
Wageningen University. Promotor(en): Paul Struik, co-promotor(en): Willemien Lommen. - [S.l. : S.n. - ISBN 9789085049159 - 148
plectranthus - agronomie - agronomische kenmerken - planten met knollen - knollen - gewassen - etnobotanie - ethiopië - knolvorming - gewasfysiologie - economische botanie - nieuwe cultuurgewassen - agro-ecologie - plectranthus - agronomy - agronomic characteristics - tuberous species - tubers - crops - ethnobotany - ethiopia - tuberization - crop physiology - economic botany - new crops - agroecology

Keywords: Development, morphology, plant density, potato, radiation interception, radiation use efficiency, seed size, seed tuber, spacing, stolon, tipping, tuber


Plectranthus edulis (Vatke) Agnew (Lamiaceae) is an ancient Ethiopian tuber crop grown in mid and high altitude areas in the north, south and south-west of Ethiopia. Cultivation dates back from c. 3000 BC, but in recent years its acreage and production have declined. Renewed interest to conserve the crop and increase its production is limited by absence of accurate information on growth, development and cultural practices of P. edulis. This project aimed at providing the basic knowledge needed to direct further applied research.
A standard production technique was developed after interviewing farmers in Chencha and Wolaita in southern Ethiopia, and was used in later experiments. The standard planting material chosen were de-sprouted tuber pieces, prepared from a medium (12–15 cm) sized mother tuber broken into three pieces. Three pieces were planted per hole, at a hole spacing of 75  90 cm. Shoot tipping (pinching; the removal of the apices with 12 leaf pairs) was carried out when the crop was 10–15 cm high.
The general structure of the crop was similar to that of Irish potato. Plant components were: the seed tuber pieces, sprouts, main stems, branches, leaves, inflorescences, fruits, seeds, roots, stolons and tubers. The crop had a long growing period. In two growth studies, maximum fresh tuber yields were attained c. 34 weeks after planting (WAP). Above-ground development was characterised by a late emergence (c. 4 weeks), a slow development of the canopy after emergence until full ground cover was attained (c. 20 weeks), a very short period during which ground cover was full (c. 2 weeks) and a relative fast decline in ground cover thereafter (6−8 weeks). Primary and secondary branches constituted the major part of the canopy. The first stolons were formed c. 1012 WAP on below-ground nodes of main stems and primary branches. Tubers were first recorded at 18 WAP as a swelling on the tip of the stolon and sometimes as a swelling of the middle part of stolons. Tubers attained a maximum length of 2025 cm, and a maximum diameter of c. 2 cm. Aerial stolons were initiated 1216 weeks later than below-ground stolons and could be up to 2.5 m long.
The increase in tuber fresh weight with time was realized by an increase in both number of tubers and in average weight per tuber over the entire tuber formation period. Fresh tuber yields at 34 WAP were 4549 Mg ha1. Yield levels in other sets of experiments in which the harvest date was chosen arbitrarily were c. 21 Mg ha1 (29.7 WAP) and c. 30 Mg ha1 (34.7 WAP). Experimental yields were very high compared to those reported by farmers.
Nevertheless, in growth studies, the average daily dry matter production of the crop over the whole growing period was only 4.2−4.6 g m2 day1. The dry matter production was limited by a poor radiation interception by the canopy – only one third of the incident radiation was intercepted − and a low radiation use efficiency (RUE) – on average only 1.59 g MJ1 photosynthetically active radiation (PAR). RUE gradually increased after emergence to about 2.7 g MJ1 PAR when tuber formation was still in an early stage (24−26 WAP), but then declined because of a stagnation or decline in total crop dry weight, that lasted several weeks. Dry matter production decreased in that period because the decrease in canopy dry matter – especially stem dry matter − was not yet compensated for by the increase in tuber dry matter. This was attributed partly to a still limited capacity of the tubers to convert and / or store assimilates in this stage. Later this changed and total dry weight and RUE increased again. Harvest index was 8199% at the moment when tuber yield was maximum.
Shoot tipping significantly increased ground cover and delayed canopy senescence. Tipping also had a positive – though not always significant – effect on tuber yield. Tipping enhanced early stolon formation, but did not consistently affect the number of stolons later in the growing season
Because differences among tipped treatments were not large, limiting the tipping frequency to one will help to save time, labour and money.
Across experiments in which the number and size of the tuber pieces planted per hole were varied, the tuber fresh weight increased when the number of main stems per m2 increased up to 2.53 main stems per m2. This sufficiently high stem number could usually be achieved by planting sufficient seed tuber material (equalling at least one medium-sized mother tuber per hole) and breaking it into two or three pieces. This confers with the farmers practice. Over all treatments, an increase in fresh tuber yield was never realized by merely increasing the individual tuber weight, but either by combined effects on number of tubers and individual tuber fresh weight or by an effect on number of tubers alone.
A further increase in radiation interception by advancing and improving canopy development could likely be achieved by planting larger seed pieces, pre-sprouting the seed tuber pieces and using a higher plant density. However, the below ground development should be geared to that. At present the late initiation and formation of tubers already seems to limit production, and this should be improved when an enhanced canopy cover should result also in higher tuber yield.
On short term notice, however, the major constraints to concentrate on will be the shortage of seed tubers and the poor storability of the progeny tubers. Shortage of seed tubers was mentioned by the interviewed P. edulis farmers as a major constraint and the principle reason for the decline in production of P. edulis. The present practice by farmers of storing tubers in situ in the ground was shown to reduce tuber fresh weights by 3659% and the number of tubers by 1848% in 6 weeks.



Potato production and innovative technologies. Proceedings Potato Russia International Conference, Moscou Agust 21-22, 2007
Haverkort, A.J. ; Anisimov, B.V. - \ 2007
Wageningen, the Netherlands : Wageningen Academic Publishers - ISBN 9789086860425 - 422
solanum tuberosum - aardappelen - agronomie - marketing - voedselkwaliteit - pootaardappelen - gewasbescherming - plantenveredeling - biotechnologie - potatoes - agronomy - food quality - seed potatoes - plant protection - plant breeding - biotechnology
This comprehensive book is the result of the Potato Russia international conference that took place in August 2007 in Moscow. It begins with a series of papers that give an excellent overview of consumer behaviour and marketing with examples from various countries in the world. The quality of processing and ware potato and methods of quantifying it, is addressed by papers that highlight its need and reveal new approaches and techniques. The newest developments in technology, mechanization and storage are highlighted in papers from eastern and western Europe. The importance and benefits of having adequately functioning seed potato systems with up to date rapid multiplication systems is shown in chapters from various countries with a special contribution on the commercial quality standards of the United Nations Economic Commission for Europe (UNECE). Developments of recent agronomic and crop management practices are illustrated with examples of countries in technological and market transition. Innovations in crop protection put special emphasis on diagnostics and detection of resistance levels, among others, against wart. The extensive Russian breeding programmes - with value for the global potato community are highlighted in the breeding section with additional papers from Japan and the Netherlands. The book ends with a series of papers on molecular aspects of innovative breeding.
Participatory development of weed management technologies in Benin
Vissoh, P.V. - \ 2006
Wageningen University. Promotor(en): N.G. Röling; Thomas Kuijper; A. Ahanchedé; V. Agbo. - [S.l.] : S.n. - ISBN 9085044340 - 187
onkruiden - onkruidbestrijding - technologie - benin - ontwikkeling - participatie - agronomie - weeds - weed control - technology - development - participation - benin - agronomy
Converging strategies by farmers and scientists to improve soil fertility and enhance crop production in Benin
Saidou, A. - \ 2006
Wageningen University. Promotor(en): Thomas Kuijper; Paul Richards; D.K. Kossou; V. Agbo. - [S.l.] : S.n. - ISBN 9085044332 - 225
bodemvruchtbaarheid - agronomie - boeren - kleine landbouwbedrijven - landbouwkundig onderzoek - participatie - teeltsystemen - benin - soil fertility - agronomy - farmers - small farms - agricultural research - participation - cropping systems - benin
Investeringsimpuls riet
Jongschaap, R.E.E. ; Colon, L.T. ; Dolstra, O. - \ 2005
Wageningen : Plant Research International (Nota / Plant Research International 370) - 32
phragmites australis - agronomie - gewasbescherming - plantenveredeling - genetische variatie - nederland - economische botanie - nieuwe cultuurgewassen - agronomy - plant protection - plant breeding - genetic variation - netherlands - economic botany - new crops
Riet is een gewas met veel nuttige functies zoals biomassaproductie voor energiewinning en de absorptie van nutriënten en zware metalen bij afvalwaterzuivering. Het doel van deze literatuurstudie is om a) riet als productief gewas te waarderen op agronomische kenmerken en te zoeken naar genetische variatie van die kenmerken die de teelt economisch en maatschappelijk verhogen en b) om om de genoemde kenmerken te kwantificeren voor Nederlandse of West-Europese omstandigheden
Changing rural areas: exploring future agriculture in the Netherlands and EU
Oenema, O. - \ 2004
Wageningen : Alterra (Alterra-rapport 1038) - 72
agronomie - duurzaamheid (sustainability) - platteland - plattelandsontwikkeling - landbouwontwikkeling - innovaties - modernisering - overheidsbeleid - nederland - agronomy - sustainability - rural areas - rural development - agricultural development - innovations - modernization - government policy - netherlands
This booklet provides a brief overview of the results of 9 studies exploring the challenges, barriers and dilemmas of agriculture and rural areas in the next three decades. The purpose of these studies was to assist policy makers in (re)shaping policies for agriculture, environment and spatial planning. Each chapter quickly summarizes the major findings of a study and the lessons to be learned from that study. All studies have been carried out by researchers from Wageningen-UR and approaches, views and conclusions expressed may be biased to some extend by experiences from The Netherlands, where the 'transition towards sustainable agriculture' receives considerable attention from policy makers. Most studies presented here used the triple P concept (People, Planet, Profit) and a 'Roadmap' with five basic questions (Why? What? How? Where? How much?) as common framework for the analyses
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