http://www.africarice.org AfricaRice Publications http://www.africarice.org/LOGO-africarice-landscape.png http://www.africarice.org Fri, 6 Oct 2017 00:00:01 GMT 'human' en Copyright AfricaRice 2017 africarice@cgiar.org (R.Raman) http://www.rssboard.org/rss-specification https://tinyurl.com/ybgyn4ow Land Use Land Cover Change (LULCC) has a significant impact on water resources and ecosystems in sub-Saharan Africa (SSA). On the basis of three research projects we aim to describe and discuss the potential, uncertainties, synergies and science-policy interfaces of satellite-based integrated research for the Kilombero catchment, comprising one of the major agricultural utilized floodplains in Tanzania. LULCC was quantified at the floodplain and catchment scale analyzing Landsat 5 and Sentinel 2 satellite imagery applying different adapted classification methodologies Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/y9smd7ck Performance of a Sifang mini rice combine, originally developed in China, was evaluated under local farmer field conditions in Benin. Results from field evaluation show that the combine worked satisfactorily on less dense rice fields with minimal weeds at grain moisture contents between 19.1% and 20.1% w.b. on soils with moisture content from 23% to 33% d.b. while causing no significant changes to soil physical properties. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yb7o5ak2 Parasitic weeds are a severe problem in rain-fed rice production ecosystems in sub-Saharan Africa. In this study, effects of sowing time of rice on parasitic weed infection and crop yields were investigated. Field experiments were conducted in Striga asiatica-infested upland and Rhamphicarpa fistulosa-infested lowland systems from 2012 to 2014 in Kyela district, Tanzania. In each system, three rice varieties were planted at five sowing times, the first coinciding with the start of the rainy season and the four other ones followed each at two weeks’ intervals. The chosen rice varieties were the late maturing local varieties Supa India (upland and lowland) and Mwangulu (upland) and earlier-maturing NERICA-14 (upland), NERICA-L-20 (lowland) and IR64 (lowland) as alternatives. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/y7wpgyr3 The rain-fed lowland rice weed Rhamphicarpa fistulosa (Rice Vampireweed) is a facultative root parasitic plant. Growth and reproduction of R. fistulosa benefit considerably from parasitism, but how this affects the host plant is not well established. We determined accumulation and partitioning of rice–parasite biomass in two pot experiments. First, rice (cv. IR64) was grown under eight R. fistulosa densities (15–1000 seeds per pot) with two sampling times. Next, 2 parasite densities (6 and 13 plants per pot) were combined with 9 destructive samplings. Infection increased host root: shoot ratios and decreased host plant height, leaf area and tiller number. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yavdfafh Rice yellow mottle virus (RYMV) disease is a serious constraint to the cultivation of rice in Africa and selection for resistance is considered to be the most effective management strategy. The aim of this study was to characterize the resistance of Tog5307, a highly resistant accession belonging to the African cultivated rice species (Oryza glaberrima), that has none of the previously identified resistance genes to RYMV. The specificity of Tog5307 resistance was analyzed using 18 RYMV isolates. While three of them were able to infect Tog5307 very rapidly, resistance against the others was effective despite infection events attributed to resistance-breakdown or incomplete penetrance of the resistance. Segregation of resistance in an interspecific backcross population derived from a cross between Tog5307 and the susceptible Oryza sativa variety IR64 showed that resistance is dominant and is controlled by a single gene, named RYMV3. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yd9v9vb7 Phenology and time of flowering are crucial determinants of rice adaptation to climate variation. A previous study characterized flowering responses of 203 diverse indica rices (the ORYTAGE panel) to ten environments in Senegal (six sowing dates) and Madagascar (two years and two altitudes) under irrigation in the field. This study used the physiological phenology model RIDEV V2 to heuristically estimate component traits of flowering such as cardinal temperatures (base temperature (Tbase) and optimum temperature), basic vegetative phase, photoperiod sensitivity and cold acclimation, and to conduct a genome-wide association study for these traits using 16 232 anonymous single-nucleotide polymorphism (SNP) markers. The RIDEV model after genotypic parameter optimization explained 96% of variation in time to flowering for Senegal alone and 91% for Senegal and Madagascar combined. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yaazznyv Low night and high day temperatures during sensitive reproductive stages cause spikelet sterility in rice. Phenotyping of tolerance traits in the field is difficult because of temporal interactions with phenology and organ temperature differing from ambient. Physiological models can be used to separate these effects. A 203-accession indica rice diversity panel was phenotyped for sterility in ten environments in Senegal and Madagascar and climate data were recorded. Here we report on sterility responses while a companion study reported on phenology. The objectives were to improve the RIDEV model of rice thermal sterility, to estimate response traits by fitting model parameters, and to link the response traits to genomic regions through genome-wide association studies (GWAS). RIDEV captured 64% of variation of sterility when cold acclimation during vegetative stage was simulated, but only 38% when it was not. The RIDEV parameters gave more and stronger quantitative trait loci (QTLs) than index variables derived more directly from observation. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yc9kc9wh This paper investigates the impact of NERICA rice adoption on household food security and human health, using country-wide cross-sectional data of 502 rice farming households in The Gambia. We used food consumption scores and the number of household sick days per capita as outcome indicators of food security and health, respectively. The instrumental variable approach was used to identify causal effects of NERICA adoption on food security and health. We found significant differences in some key socio-economic and demographic characteristics between adopters and non-adopters of NERICA. To control for such differences and allow a causal interpretation of the impact of NERICA adoption, we estimated the Local Average Treatment Effect (LATE). Our analyses indicated that adoption of NERICA significantly increased household food security by 14 percentage points. This helps severely food insecure households to achieve acceptable food security status by enabling them to acquire cereals and tubers, pulses, vegetables and fruits on a daily basis. However, there was no significant impact of NERICA adoption on human health. Our findings indicate that NERICA can play an important role in fighting against food insecurity in The Gambia. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yd5wej4o Surveys of rice growing areas were conducted from 2011 to 2015 with the aim of assessing the importance of bacterial diseases in Benin, Burkina Faso, The Gambia, Ghana, Ivory Coast, Mali, Niger, Nigeria, Senegal, Tanzania and Togo. Between 100 to 500 samples showing symptoms consistent with leaf blight were collected from each country. Symptoms included yellow-brown discolourations along one of the two leaf blades, turning brown to dark-brown with age (Fig. 1). Severely affected leaves developed necrotic patches and died. Fri, 6 Oct 2017 00:00:01 GMT Journal Articles https://tinyurl.com/ycr5vczm African Journal of Agricultural and Resource Economics--Urban demand for fragrant rice is increasing rapidly in Senegal, but little is known about the value of rice fragrance and the drivers of its demand. We conducted experimental auctions in Dakar to elicit urban consumers’ willingness to upgrade from non-fragrant to fragrant rice and their willingness to pay for domestic versus imported fragrant rice, and assessed the drivers of demand for rice Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/y8bbtd7g PLoS ONE--Inland valleys are becoming increasingly important agricultural production areas for rural households in sub-Saharan Africa due to their relative high and secure water availability and soil fertility. In addition, inland valleys are important as water buffer and biodiversity hot spots and they provide local communities with forest, forage, and fishing resources. As different inland-valley ecosystem functions may conflict with agricultural objectives, indiscriminate development should be avoided. This study aims to analyze the diversity of inland valleys in Sierra Leone and to develop guidelines for more precise interventions. Land use, biophysical and socio-economic data were analyzed on 257 inland valleys using spatial and multivariate techniques. Five cluster groups of inland valleys were identified: (i) semi-permanently flooded with high soil organic carbon (4.2%) and moderate available phosphorus (10.2 ppm), mostly under natural vegetation; (ii) semi-permanently flooded with low soil organic carbon (1.5%) and very low available phosphorus (3.1 ppm), abandoned by farmers; (iii) seasonally flooded with moderate soil organic carbon (3.1%) and low available phosphorus (8.3 ppm), used for rainfed rice and off-season vegetables produced without fertilizer application for household consumption and market; (iv) well drained with moderate soil organic carbon (3.8%) and moderate available phosphorus (10.0 ppm), used for rainfed rice and off-season vegetables produced with fertilizer application for household consumption and market; and (v) well drained with moderate soil organic carbon (3.6%) and moderate available phosphorus (11 ppm), used for household consumption without fertilizer application. Soil organic carbon, available phosphorus, hydrological regime, physical accessibility and market opportunity were the major factors affecting agricultural intensification of inland valleys. Opening up the areas in which inland valleys occur through improved roads and markets, and better water control through drainage infrastructures along with an integrated nutrient management would promote the sustainable agricultural use of inland valleys. Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/ya3gjy68 Rice--There is still limited quantitative understanding of how environmental factors affect sterility of Environment-conditioned genic male sterility (EGMS) lines. A model was developed for this purpose and tested based on experimental data from Ndiaye (Senegal) in 2013-2015. For the two EGMS lines tested here, it was not clear if one or more recessive gene(s) were causing male sterility. This was tested by studying sterility segregation of the F2 populations. Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/ydbwuszr Diversity--Rice is a staple food in West Africa, where its demand keeps increasing due to population growth. Hence, there is an urgent need to identify high yielding rice cultivars that fulfill this demand locally. Rice hybrids are already known to significantly increase productivity. This study evaluated the potential of Asian hybrids with good adaptability to irrigated and rainfed lowland rice areas in Mali, Nigeria, and Senegal. There were 169 hybrids from China included in trials at target sites during 2009 and 2010. The genotype × environment interaction was highly significant for grain yield indicating that the hybrids’ and their respective cultivar checks’ performance differed across locations. Two hybrids had the highest grain yield during 2010 in Mali, while in Nigeria, four hybrids in 2009 and one hybrid in 2010 had higher grain yield and matured earlier than the best local cultivar. The milling recovery, grain shape and cooking features of most hybrids had the quality preferred by West African consumers. Most of the hybrids were, however, susceptible to African rice gall midge (AfRGM) and Rice Yellow Mottle Virus (RMYV) isolate Ng40. About 60% of these hybrids were resistant to blast. Hybrids need to incorporate host plant resistant for AfRGM and RYMV to be grown in West Africa. Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yacf5lu2 German Development Institute / Deutsches Institut für Entwicklungspolitik (DIE)--With the Sustainable Development Goals (SDGs) has come a renewed global interest in ending hunger, achieving food security and preventing natural resource degradation. Despite this renewed interest and increased commitments to invest in agricultural development, there is an ongoing debate over the pathways to sustainability. The debate centres on sustainable agricultural intensification (SAI) and agroecological intensification (AEI) pathways to agricultural sustainability. Using a systematic literature review approach, this study examines the debate over AEI and SAI. This study employs a theoretical framework based on the economic, social, and ecological dimensions of sustainable agriculture within a policy and institutional space. Based on the sustainability dimensions, a discourse analytical technique is applied to unravel the debate. The results reveal that proponents of the SAI pathway are predominantly private sector actors, while support for the AEI pathway comes mainly from international donors, NGOs and civil society actors. Both pathways aim to promote food security; however, the actors differ on discourse relating to the concept of farming, the role of GMOs, the scale of operation, and land use, as well as views on the social, economic, and ecological dimensions of sustainability. Resolving these differences requires a blended sustainability approach that moves beyond the current AEI and SAI debate by acknowledging the tradeoffs and synergies of the socio-economic and ecological dimensions of the different pathways to sustainability. Knowledge platforms will support this shift, and an enabling policy and institutional environment will provide the right incentives to promote sustainable agriculture. Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/y7nls8lj Achieving sustainable cultivation of rice--Rice provides 20% of the world’s food energy, and increased rice production owing to growing demand needs to be derived mainly from existing agricultural land. This requires reducing the ‘yield gap’, which is defined as the difference between potential yield and average on-farm yield obtained by farmers. In this chapter, we provide case studies of yield gap analyses using different benchmarks (potential yield, experimental yield and best farmers’ yield) for estimating yield gaps. We start with studies focusing on the quantification of yield gaps and then describe studies with a focus on identification of the causes of yield gaps. We conclude with a discussion of the challenges to achieving better quantification of yield gaps and their causes, and the implications of yield gap studies for sustainable agricultural development to meet future rice demand. Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/ybnlbv2s Achieving sustainable cultivation of rice--The rice plant is an ideal host for many insect species. All of the plant parts are vulnerable to insect-feeding from the time of sowing till harvest. There are over 800 insect species damaging rice in one way or another, although the majority of them do very little damage. In tropical Asia only about 20 species are of major importance. In Africa, 15 species of insects are considered major pests of rice and in the Americas about 20 species are considered major pests. To develop effective pest management strategies, it is essential to properly identify and to understand the biology and ecology of insect pests and the arthropods that help regulate their populations. This book effectively utilizes the unique knowledge and expertise of leading rice entomologists from Africa, Asia and the Americas to provide the first global coverage of rice insect pests. The discussion of each pest includes geographical distribution, plant hosts other than rice, description and biology, plant damage and ecology. Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yat7rm4s Achieving sustainable cultivation of rice--Rice farmers face many abiotic and biotic constraints in their quest to increase rice production. In conjunction with the introduction of new high yielding drought and flood tolerant rice varieties, increasing yields will require a reduction in losses to insect pests. This chapter discusses current strategies for managing rice insect pests in an environmentally sustainable manner. It reviews integrated pest management (IPM) as it applies to rice cultivation, and includes discussions of the impacts of cultural practices, conservation biological control and augmentative biological control, and the selective use of insecticides. Finally, dissemination mechanisms for rice IPM are considered. Mon, 17 Jul 2017 00:00:01 GMT Journal Articles https://tinyurl.com/y9q7ynwt Nature Plants--Grain size is one of the most important components of grain yield and selecting large seeds has been a main target during plant domestication. Surprisingly, the grain of African cultivated rice (Oryza glaberrima Steud.) typically is smaller than that of its progenitor, Oryza barthii. Here we report the cloning and characterization of a quantitative trait locus, GL4, controlling the grain length on chromosome 4 in African rice, which regulates longitudinal cell elongation of the outer and inner glumes. Interestingly, GL4 also controls the seed shattering phenotype like its orthologue SH4 gene in Asian rice. Our data show that a single-nucleotide polymorphism (SNP) mutation in the GL4 gene resulted in a premature stop codon and led to small seeds and loss of seed shattering during African rice domestication. These results provide new insights into diverse domestication practices in African rice, and also pave the way for enhancing crop yield to meeting the challenge of cereal demand in West Africa. Mon, 29 May 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yaat5o5c Cereal Chemistry--The development of innovative legume-enriched rice products is a promising way to exploit rice varieties with a low sensory grade. In this work, a multidisciplinary approach was applied to the characterization of extruded breakfast cereals prepared from African-grown Oryza glaberrima (cv. Viwonor) or Oryza sativa (cv. Jasmine 85) enriched with 30% cowpea flour, obtained from sprouted or nonsprouted cowpea. Regardless of the rice species, addition of sprouted cowpea flour conferred a peculiar volatiles profile, rich in sour, bitter, and astringent taste. Protein structural indices provided molecular insights about the macroscopic differences among samples. Extruded products from O. glaberrima were characterized by lower expansion rates with respect to those obtained from O. sativa, regardless of the type of cowpea flour. Sprouting time had a positive influence on the hardness of extruded glaberrima-based products, facilitating formation of a more compact matrix, but it did not influence sativa-based products. Therefore, the breakdown of protein during sprouting appeared fundamental for the incorporation of legume proteins in more compact matrices, such as the one from sativa rice. In the glaberrima-based products, addition of sprouted cowpea resulted in further loosening of the structure, and this was more evident at increased sprouting times. Mon, 29 May 2017 00:00:01 GMT Journal Articles https://tinyurl.com/yanbwfco Euphytica--Rice is mainly a self-pollinating crop, but some outcrossing has been reported. Outcrossing with an undesirable donor would lead to the creation of segregants or off-types, which would adversely affect genetic purity and uniformity of the crop. Outcrossing rates in rice under field conditions were investigated using cultivar WAB96-1-1 as a pollen donor and WAB56-104, NERICA 2, NERICA 4 and NERICA 7 as pollen recipients. Levels of outcrossing were investigated up to 30 m from the pollen donor. Dominant morphological markers of red kernel colour and pubescent leaves of the donor were used to identify hybrids. A total of 721 134 plants were investigated. There was an average outcrossing rate of 0.7 ± 0.51%, with a potential outcrossing rate of 2.45 ± 0.86%. Outcrossing rates decreased with increase in distance. It ranged from 2.45% at 0.2 m from the donor to 0.05% at 25 m from the donor. Differences were observed between genotypes and seasons. In season 1 the highest average outcrossing rate of 1.2 ± 0.63% was with WAB56-104 and in season 2 it was 1.1 ± 0.69% with NERICA 4. Outcrossing occurred up to 30 m from the donor. This has implications for germplasm management and conservation and the production of high quality seed. Spatial isolation remains the most practical method to prevent undesirable gene flow. The study indicated that red kernel colour and leaf pubescence can be used to effectively assess outcrossing under field conditions in rice. Mon, 29 May 2017 00:00:01 GMT Journal Articles https://tinyurl.com/y7e89hpf Crop Protection--Rain-fed rice production in sub-Saharan Africa is often hampered by parasitic weeds. This study assessed farmers’ awareness, use, preference and adoption criteria of parasitic weed management practices in rain-fed rice production environments in Tanzania. Surveys and workshops were organized in three affected rice growing areas in Morogoro-rural, Songea and Kyela district, supplemented with on-farm experiments in Kyela. In all districts, farmers were aware of the locally occurring parasitic weed species, Rhamphicarpa fistulosa (lowland) and Striga asiatica (upland), and they considered these weeds more problematic than non-parasitic weeds. Though they mostly practise hand weeding, farmers were aware of a wide range of control options. Local access, affordability, ease of implementation and control efficacy were considered important criteria for adoption, whereas trade-offs, like lack of preferred grain quality traits in resistant varieties, were mentioned as an important break on adoption. Based on informal discussions with farmers, altered sowing times, resistant rice varieties and soil amendments were marked as feasible control options and tested in a farmer-participatory manner in four years of experimentation in upland and lowland fields. In both types of fields, the contribution of soil amendment to parasitic weed suppression was not evident, but rice husk was marked as a suitable and cheap alternative to inorganic fertilizers. Control of R. fistulosa in lowlands was perceived to be best realized by early crop establishment, escaping major parasite damage due to the relatively slow early development of this weed species. The local variety Supa India, appreciated for its grain qualities and marketability, remained the preferred variety. For the control of S. asiatica, late planting was preferred, requiring a short-duration variety to minimize risk of drought stress during grain filling. The short-duration NERICA-10 was most preferred, as it combined a favourable short cycle length with resistance to S. asiatica and good grain appearance. Farmer participation in technology testing showed to be crucial in defining locally adapted and acceptable parasitic weed control strategies. Yet, it is argued that without lifting important constraints related to credit and input supply, it will be impossible to sustainably solve the parasitic weed problem in rain-fed rice. Mon, 29 May 2017 00:00:01 GMT Journal Articles https://tinyurl.com/leoulhg Global Food Security--The dissemination of improved rice varieties could contribute significantly to achieving food security and reducing poverty in sub-Saharan Africa (SSA). This study assesses the number of households and individuals lifted out of poverty and food insecurity. Metadata and primary data collected from sixteen countries were analyzed. A positive impact of improved varieties on food security and poverty reduction was observed over the period 2000–2014. In addition, the rate of adoption of these varieties increased over these years and this increase was more significant after the 2008 food crisis. Average income also increased from US$ 25 capita–1 to US$ 58 capita–1 for NERICA adopters. These trends could be enhanced by addressing production constraints and certified seed bottlenecks. Fri, 7 Apr 2017 00:00:01 GMT Journal Articles https://tinyurl.com/mt5ge5k Journal of Irrigation and Drainage Engineering--The unavailability of some meteorological variables, especially solar radiation and wind speed, is the main constraint for reference evapotranspiration (ETo) estimation using the standard United Nations Food and Agriculture Organization (FAO) Penman–Monteith (FAO-PM) equation in most developing countries. The application of ETo methods with fewer input requirements is necessary under limited climatic data conditions. The FAO-PM method under limited data conditions and nine of Valiantzas’ equations were evaluated for daily ETo estimation in a humid climate in Uganda. The FAO-PM method with missing relative humidity data performed very well across Uganda, whereas using the long-term local wind speed average values in place of missing wind speed data resulted in inaccurate ETo estimates. Under missing solar radiation measurements, the FAO-PM method showed different performances relative to the locations. When more than one climatic variable is missing, the FAO-PM method yielded poor ETo estimates compared to the FAO-PM method with full climatic data. The performance of Valiantzas’ equations depends on data requirements: the more meteorological inputs, the higher the ETo accuracy. http://dx.doi.org/10.1061/(ASCE)IR.1943-4774.0001191 Fri, 7 Apr 2017 00:00:01 GMT Journal Articles https://tinyurl.com/nxzglej Global Food Security--The dissemination of improved rice varieties could contribute significantly to achieving food security and reducing poverty in sub-Saharan Africa (SSA). This study assesses the number of households and individuals lifted out of poverty and food insecurity. Metadata and primary data collected from sixteen countries were analyzed. A positive impact of improved varieties on food security and poverty reduction was observed over the period 2000–2014. In addition, the rate of adoption of these varieties increased over these years and this increase was more significant after the 2008 food crisis. Average income also increased from US$ 25 capita–1 to US$ 58 capita–1 for NERICA adopters. These trends could be enhanced by addressing production constraints and certified seed bottlenecks. http://doi.org/10.1016/j.gfs.2017.03.001 Fri, 7 Apr 2017 00:00:01 GMT Journal Articles https://tinyurl.com/m38bqx9 New Phytologist--The parasitic weeds Striga asiatica and Striga hermonthica cause devastating yield losses to upland rice in Africa. Little is known about genetic variation in host resistance and tolerance across rice genotypes, in relation to virulence differences across Striga species and ecotypes. Diverse rice genotypes were phenotyped for the above traits in S. asiatica- (Tanzania) and S. hermonthica-infested fields (Kenya and Uganda) and under controlled conditions. New rice genotypes with either ecotype-specific or broad-spectrum resistance were identified. Resistance identified in the field was confirmed under controlled conditions, providing evidence that resistance was largely genetically determined. Striga-resistant genotypes contributed to yield security under Striga-infested conditions, although grain yield was also determined by the genotype-specific yield potential and tolerance. Tolerance, the physiological mechanism mitigating Striga effects on host growth and physiology, was unrelated to resistance, implying that any combination of high, medium or low levels of these traits can be found across rice genotypes. Striga virulence varies across species and ecotypes. The extent of Striga-induced host damage results from the interaction between parasite virulence and genetically determined levels of host-plant resistance and tolerance. These novel findings support the need for predictive breeding strategies based on knowledge of host resistance and parasite virulence. https://doi.org/10.1111/nph.14451 Mon, 20 Mar 2017 00:00:01 GMT Journal Articles https://tinyurl.com/n3sxzqd European Journal of Agronomy--Although increase in rice (Oryza spp.) production is a common objective for rice-producing countries in sub-Saharan Africa (SSA), basic information on yield and its variation at farm level is lacking. Field surveys were conducted in irrigated lowland (IL), rainfed lowland (RL), and rainfed upland (RU) rice production systems in 19 SSA countries in the 2012–2014 wet seasons. Mean yield varied widely across sites: 2.2–5.8 t/ha, 1.1–5.2 t/ha, and 1.0–2.5 t/ha in IL, RL, and RU, respectively. Rice yield levels differed between the agro-ecological zones (AEZs) with the highest yield in the semi-arid zone in IL, and in the highlands zone for RL and RU. Cluster analysis identified four groups using mean yields, coefficient of variation, and skewness of yield distribution of 42 site–production system combinations. Grouping was related to production system, AEZ, and field water condition. A high-yielding group with 5.3 t/ha mean yield and negative skewness had only four site–production system combinations. Other groups had mean yields from 1.6 to 3.5 t/ha with positive skewness. In these groups, research and development priority for lifting rice yield could be given to low-yielding IL and RL sites with large yield gaps. Raising rice yield in the humid zone irrespective of the production systems and RU across AEZs remain major challenges. Further assessment of the impact of farmers’ agricultural practices on yield variation is warranted to identify potential interventions to realize further yield enhancement. http://dx.doi.org/10.1016/j.eja.2016.12.010 Mon, 20 Mar 2017 00:00:01 GMT Journal Articles https://tinyurl.com/kreyxe3 Journal of Risk Research--Invasive species such as Ambrosia (an annual weed) pose a biosecurity risk whose management depends on the knowledge, attitudes and practices of many stakeholders. It can therefore be considered a complex policy and risk governance problem. Complex policy problems are characterised by high uncertainty, multiple dimensions, interactions across different spatial and policy levels, and the involvement of a multitude of actors and organisations. This paper provides a conceptual framework for analysing the multi-level and multi-actor dimensions of Ambrosia management. Potential and existing public, private and public–private management strategies are identified to address the interests and needs of different actor groups across different levels. We conclude that policies that promote a mix of public and private Ambrosia management strategies may respond better to the needs and interests of different actor groups across different levels than a one-size-fits-all approach. However, multiple policy strategies need to be aligned in order to lead to synergies and spreading coherent messages to the public. Collaboration may enhance the likelihood of biosecurity management and risk governance of Ambrosia being adequately implemented and enforced. http://ezproxy.library.wur.nl/login?url=http://dx.doi.org/10.1080/13669877.2016.1247376 Mon, 20 Mar 2017 00:00:01 GMT Journal Articles https://tinyurl.com/ko74uj7 LWT - Food Science and Technology--Rice is a staple food worldwide. In this study, seven African rice (Oryza glaberrima) accessions (ARAs) were evaluated for grain quality attributes, pasting, thermal and in vitro digestion properties in comparison with two Asian rice (Oryza sativa) varieties (ARVs) and a developed cross (O. sativa × O. glaberrima cross). The ARAs were intermediate to high amylose rice types and their 1000-kernel weight and bulk densities were comparable to the ARVs. Volume expansion ratios of cooked kernels overlapped among rice varieties ranging from 2.5 to 4.4 and the ARAs had relatively lower cooking solids loss and harder texture compared to the ARVs which were softer and more adhesive. Flours from the ARVs formed more viscous slurries, exhibiting higher breakdown viscosities than the ARAs. Gelatinization transition temperatures and enthalpies were significantly higher for flours from ARAs than the ARVs suggesting more stable crystal structure for ARAs. This is supported by the higher energy required to liquefy the retrograded ARAs flour gels. The cooked samples of ARAs and ARVs showed close starch digestibility indices with expected glycemic index (eGI) ranging from 71 to 78. Differences observed in cooking characteristics and textural properties between ARAs and ARVs may be partially due to the ARAs’ high amylose content. http://dx.doi.org/10.1016/j.lwt.2016.09.023 Mon, 20 Mar 2017 00:00:01 GMT Journal Articles https://tinyurl.com/l5d3sre Field Crops Research : Rice (Oryza spp.) is the major staple food for most countries in West Africa, but local production does not meet demand. Rice is grown mainly by smallholder farmers, and yields are generally low with high temporal and spatial variability. Low yields have been attributed to unfavorable climate conditions, poor soil quality, and sub-optimum agricultural practices. The objectives of this study were to assess variation in yields of three major rice production systems (irrigated lowland, rainfed lowland, and upland) across three climatic zones (semi-arid, sub-humid, and humid), and identify factors affecting that variation. We analyzed data on yield, climate, soil, and agricultural practices for 1305 farmers’ fields at 22 sites in 11 West African countries between 2012 and 2014. A boundary function approach was used to determine attainable yields. Random forest algorithm was used to identify factors responsible for yield variation. Average rice yield was 4.1, 2.0, and 1.5 t ha−1 in irrigated lowland, rainfed lowland, and rainfed upland systems, respectively, with maximum attainable yields of 8.3, 6.5, and 4.0 t ha−1. Yield difference between attainable and average yield tended to be higher in irrigated and rainfed lowland systems. In those two systems, yields were highest in the semi-arid zone, while no difference in yields among climatic zones was apparent for upland rice. High rice yields were associated with high solar radiation, high maximum temperature, intermediate air humidity, multiple split nitrogen (N) fertilizer applications, high frequency of weeding operations, the use of certified seeds, and well-leveled fields in the irrigated lowland system. Minimum temperature, solar radiation, rainfall, construction of field bunds, varietal choice, and the frequency of weeding operations were determinants of rice yield variation in the rainfed lowland system. Varietal choice, bird control, and frequency of weeding operations affected rice yields in the upland system. Improving access to inputs, improving input use efficiencies, and site-specific management strategies are recommended as priority interventions to boost rice yields at regional scale independent of production system and climatic zone. http://dx.doi.org/10.1016/j.fcr.2017.02.014 Fri, 17 Mar 2017 00:00:01 GMT Journal Articles