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Marginal environments are characterized by constrained agricultural potential and resource degradation attributable to biophysical and politico-socio-economic factors. These environments and the indigenous people who cultivate them rarely attract academic interest, policy studies or investment. The agricultural expertise of indigenous communities is often overlooked by decision-makers. Interventions based on mainstream crops and external technologies may fail indigenous communities where a vast range of crops are cultivated in diverse production systems and in marginal environments. Hunger, malnutrition, and poverty in indigenous communities are high. The challenges should be approached from the perspectives and resources of indigenous people. In this chapter, we discuss four biogeographical regions, arid, semi-arid, humid and mountainous, representing large parts of marginal lands and innovations, investment opportunities, and proposed action for the transformation of food systems in these areas. Marginal areas and indigenous people can benefit from improved linkages between formal and indigenous knowledge systems, participatory and demand-driven technologies, integration of indigenous knowledge in research, improvements in local crops, integrated management and access to markets. Our recommendations for the transformation of food systems in these areas include (1) Efforts to mainstream diverse value chains, (2) Development of evidence-based policies (3) Awareness of under-utilized and forgotten crops (4) Collective action and (5) Coordinated public and private investment in research and development for the empowerment of indigenous people and the development of their land.

Bambara groundnut has the potential to be used to contribute more the climate change ready agriculture. The requirement for nitrogen fixing, stress tolerant legumes is clear, particularly in low input agriculture. However, ensuring that existing negative traits are tackled and demand is stimulated through the development of markets and products still represents a challenge to making greater use of this legume. World agriculture is currently based on very limited numbers of crops, representing a significant risk to food supplies, particularly in the face of climate change which is expected to increase the frequency of extreme events. Minor and underutilised crops can help to develop a more resilient and nutritionally dense future agriculture. Bambara groundnut [Vigna subterranea (L.) Verdc.[, as a drought resistant, nitrogen-fixing, legume has a role to play. However, as with most underutilised crops, there are significant gaps in knowledge and also negative traits such as 'hard-to-cook' and 'photoperiod sensitivity to pod filling' associated with the crop which future breeding programmes and processing methods need to tackle, to allow it to make a significant contribution to the well-being of future generations. The current review assesses these factors and also considers what are the next steps towards realising the potential of this crop.

Evidence based crop diversification requires modelling for crops that are currently neglected or underutilised. Crop model calibration is a lengthy and resource consuming effort that is typically done for a particular variety or a set of varieties of a crop. Whilst calibration data are widely available for major crops, such data are rarely available for underutilised crops due to limited funding for detailed field data collection and model calibration. Subsequently, the lack of evidence on their performance will lead to the lack of interest from the policy and regulatory communities to include these crops in the agricultural development plans. In order to motivate further research into the use of state of the art techniques in modelling for less known crops, we have developed and validated an ideotyping technique that approximates the crop modelling parameters based on already calibrated crops of different lineage. The method has been successfully tested for hemp (Cannabis sativa L.) based on a well-known crop model. In this paper we present the method and provide an impetus on the way forward to further develop such methods for modelling the performance of minor crops and their varieties.•The approach works based on modelling the performance of hemp using the knowledge from an existing model that was developed for sugar cane.•The customisation uses one of the most prominent models (AquaCrop) to approximate growth coefficients for hemp (Cannabis sativa L.).•A sequential procedure was used to approximate the phenological stages in the growth model that performs well in the calibration and validation steps., Graphical abstract Image, graphical abstract

In Bambara groundnut [Vigna subterranea (L) Verdc], long photoperiods can cause a decline in pod and seed number. While negative photoperiod effects on pod yield have been reported, positive effects and the existence of genotypes less sensitive for photoperiod have not been reported. Ten geographically diverse genotypes were evaluated over 3 years under short and long photoperiod for yield‐related traits (pod number, pod weight, seed number, seed weight, and 100 seed weight), pod growth habit (geocarpic or ageocarpic pods), peduncle elongation and soil penetration, and pod set/abortion. Anatomical sections of gynophores and embryonic pod development of a highly photoperiod sensitive genotype “Ankpa‐4” from Nigeria were examined. A strong photoperiodic effect on yield component traits (pod number, pod weight, seed number, seed weight, and 100 seed weight) was observed and with considerable variation between genotypes. Three classes of photoperiod effect on pod yield were identified, (a) qualitative short‐day types; (b) quantitative short‐day types; and (c) quantitative long‐day types. In long photoperiods, above‐ground vegetative biomass and the length of lateral branches in some genotypes increased by at least twofold. Morphological and anatomical characterization of gynophores and developing pods of the most sensitive line shows continuous geocarpic growth, but with healthy embryonic pods failing to enlarge after soil penetration. Results from the yield patterns of the three phenotypic classes confirm that pods and seeds are high priority sinks, and long photoperiod alters the balance in assimilate distribution between competing yield forming processes and vegetative sinks. By exploiting the genetic variation characterized here for photoperiod requirement for pod filling, the geographical range of this crop could be extended beyond current growing regions. In the near future, we anticipate that Bambara groundnut will become a significant contributor to global food, nutritional, and environmental security once these photoperiod issues are resolved.

Shortlisting ecologically adaptable plant species can be a starting point for agricultural diversification projects. We propose a rapid assessment framework based on an ecological model that can accelerate the evaluation of options for sustainable crop diversification. To test the new model, expert-defined and widely available crop requirement data were combined with more than 100,000 occurrence data for 40 crops of different types (cereals, legumes, vegetables, fruits, and tubers/roots). Soil pH, texture, and depth to bedrock data were obtained and harmonised based on the optimal rooting depths of each crop. Global baseline temperature and rainfall data were used to extract averages at each location. To evaluate the ability of the method to capture intraspecies variation, a test was performed using more than 1000 accession records of bambara groundnut (Vigna subterranea (L.) Verdc.) as an exemplar underutilised crop. Results showed that a suitability index based on soil pH and an index that combines the thermal suitability moderated by the soil pH, texture, and depth suitability have the potential to predict crop adaptability. We show that the proposed method can be combined with traditional land use and crop models to evaluate diversification options for sustainable land and agrobiodiversity resources management.

Hemp (Cannabis sativa L.) is a multipurpose industrial crop which is mainly cultivated in temperate regions. With its high potential for economic returns for its seeds and fiber, there is growing interest in cultivating hemp in many territories including Malaysia and other Asian countries, where its cultivation is currently illegal. To date, no comprehensive study on the suitability of this crop under Malaysian conditions has been conducted. In this paper, we propose an assessment framework as a roadmap to develop the hemp industry in Malaysia and possibly other Asian countries with equatorial climates. This framework includes suitability assessment (climate and soil), crop modelling (current and future yields under climate change) and economic analysis (net present value (NPV), NPV benefit (NPVB) and benefit-cost ratio (BCR). The land suitability assessment classified hemp as an adaptable crop for most of the land in the country. The AquaCrop model, parameterised from secondary data collected from literature was used in simulations and potential yield mapping. The estimated average potential seed and fiber yield at six locations between 2010 and 2019 was 1.61 ± 0.25 and 2.78 ± 0.39 t ha–1 respectively. Using five general circulation model (GCM) simulations, yields under future climates in Malaysia showed an increase in most of the locations. The highest NPVB of 1641 USD ha–1 (BCR of 1.33) for seed was estimated under current climate conditions. Yields of 1.38 t ha–1 (seed) and 3.62 t ha–1 (fiber) are the minimum economically feasible yields with a Benefit-Cost Ratio of 1.00 suggesting a potential for hemp cultivation in comparison to countries with established hemp industries. The present framework could be used to develop a pathway for adoption of hemp as a crop for the future in tropical countries.

Main conclusion\ud \ud Crops For the Future (CFF), as an entity, has established a broad range of research activities to promote the improvement and adoption of currently underutilised crops.\ud \ud \ud Abstract\ud \ud This paper summarises selected research activities at Crops For the Future (CFF) in pursuit of its mission ‘to develop solutions for diversifying future agriculture using underutilised crops’. CFF is a research company focussed on the improvement of underutilised crops, so that they might be grown and consumed more widely with benefits to human food and nutritional security; its founding guarantors were the Government of Malaysia and the University of Nottingham. From its base in Malaysia, it engages in research around the world with a focus on species and system diversification. CFF has adopted a food system approach that adds value by delivering prototype food, feed and knowledge products. Bambara groundnut (Vigna subterranea) was adopted as an exemplar crop around which to develop CFF’s food system approach with emphasis on the short-day photoperiod requirement for pod-filling and the hard-to-cook trait. Selective breeding has allowed the development of lines that are less susceptible to photoperiod but also provided a range of tools and approaches that are now being exploited in other crops such as winged bean (Psophocarpus tetragonolobus), amaranth (Amaranthus spp.), moringa (Moringa oleifera) and proso (Panicum miliaceum) and foxtail (Setaria italica) millets. CFF has developed and tested new food products and demonstrated that several crops can be used as feed for black soldier fly which can, in turn, be used to feed fish thereby reducing the need for fishmeal. Information about underutilised crops is widely dispersed; so, a major effort has been made to develop a knowledge base that can be interrogated and used to answer practical questions about potential exploitation of plant and nutritional characteristics. Future research will build on the success with Bambara groundnut and include topics such as urban agriculture, rural development and diversification, and the development of novel foods.

LANDSUPPORT is a Horizon2020 project, funded by the European Commission, stands for" Development of Integrated Web-Based Land Decision Support System Aiming Towards the Implementation of Policies for Agriculture and Environment"(www. landsupport. eu) The project aims at developing a web-based, open-access GeoSpatial Decision Support System (S-DSS) devoted to reconciling agriculture, environmental sustainability and policy implementation. Overall, the S-DSS will contribute to the development and implementation of land use policies in Europe, and it will promote an integrated and participatory approach towards rural development and environmental policies allowing, among others, evaluation of trade-offs between different land uses. A specific tool will be implemented to face the current issue of food security and optimization of land use in agriculture for addressing the Sustainable ...

Digital agriculture is driven by the interrelated needs to increase crop production, develop sustainable food systems and cope with the global change. Databases exist for several major crops but a barrier to increasing agrobiodiversity is the lack, and dispersed nature, of information for variously termed minor, orphan or underutilised crops. In this article, we describe an attempt to build a globally accessible database that can be used to store information for underutilised crops. A relational data model was adopted due to its robustness in terms of prototyping and building user interfaces for data governance and dissemination. We have reviewed the design of related agricultural databases, data standards and crop diversification priorities, to build a data model that encompasses major elements of the value chain of crops in the food system. Due to the importance of data accuracy, we added a metadata table that stores information about the sources of all data recorded in the database. We also built a web-based user interface for data management and access. The open-access user interface allows simple data sorting and filtering operations based on the user's needs. As an example of potential use, data were used to build an automated crop selection tool that could shortlist suitable crops based on location at global scale. Other use-cases are discussed including the development of metrics, indicators for the United Nations Sustainable Development Goals and developing bespoke diversification solutions.

Soil data for Sri Lanka are available through semi-detailed series maps that were developed based on limited soil profile data combined with expert knowledge. This data plays a vital role in decisions at national and regional levels. However, the present format of this database does not allow for their wider use in crop simulation modelling and other related agricultural research that require finer scale data. This is due to the fact that cross-country profile data are not harmonised based on standard depths. Several attempts were made to produce digital soil data for Sri Lanka at different geographic scales, however, a completely harmonised data that covers variability across depths and properties is yet to be made available. In this article, we describe the first version of the open digital soil database that was developed using a database of 122 locations across the country. Soil properties were harmonised for standard depths using equal-area quadratic smoothing splines. Out of several interpolation methods that were evaluated for univariate interpolation, maps which were produced with the least overall error (RMSE) in the process of cross-validation were selected. The newly developed digital soil database contains 9 soil properties; pH, bulk density, cation exchange capacity, organic carbon, volumetric moisture content at 0.33 and 15 bars levels, sand silt and clay content. Moreover, the data are available for five standard depth layers as 0–5, 5–15, 15–30, 30–60 and 60–100 cm in raster format at 1 km spatial resolution. Both interpolated property maps and their error maps were stored in an open repository and made available for public use. The first version of all maps is also showcased online through open web mapping services. The repository will be gradually updated with higher resolution and more accurate maps as more samples become available and better interpolation method are used. This data could provide complementary information for insight generation at finer scales where limited local informaiton about soils hinders agricultural development.

Data from global soil databases are increasingly used for crop modelling, but the impact of such data on simulated crop yield has not been not extensively studied. Accurate yield estimation is particularly useful for yield mapping and crop diversification planning. In this article, available soil profile data across Sri Lanka were harmonised and compared with the data from two global soil databases (Soilgrids and Openlandmap). Their impact on simulated crop (rice) yield was studied using a pre-calibrated Agricultural Production Systems Simulator (APSIM) as an exemplar model. To identify the most sensitive soil parameters, a global sensitivity analysis was performed for all parameters across three datasets. Different soil parameters in both global datasets showed significantly (p &lt, 0.05) lower and higher values than observed values. However, simulated rice yields using global data were significantly (p &lt, 0.05) higher than from observed soil. Due to the relatively lower sensitivity to the yield, all parameters except soil texture and bulk density can still be supplied from global databases when observed data are not available. To facilitate the wider application of digital soil data for yield simulations, particularly for neglected and underutilised crops, nation-wide soil maps for 9 parameters up to 100 cm depth were generated and made available online.

Crops For the Future Research Centre (CFFRC) is currently developing CropBASE—a cross-cutting web-based platform for decision support and knowledge sharing on underutilised crops and their end uses. It provides a quantitative basis to compare underutilised crop productivity and resource-use-efficiency with that of major crops and cropping systems under current and future climate scenarios, and will include interactive tools to integrate underutilised crop data with geo-referenced information in existing and new databases. Specific crop application models form the analysis engine of CropBASE, including crop-climate, crop-quality, crop-economic models to assess agroecological suitability, nutritional value, livelihood or food security potential of underutilised crops and products at field, farm and regional scales. A geospatial information system framework will link currently available climate databases as input data for crop models. CFFRC, already using major models for a range of crops around the world under the AgMIP program, will spearhead the inclusion of specific underutilised crops into recognised crop models. After briefly introducing CropBASE, this paper presents use cases as examples comparing yield and water productivity predictions for bambara groundnut (an underutilised African legume) and pearl millet (an alternative major cereal) under current and future climate scenarios in contrasting sub-Saharan African locations.

The paper retraces the GRASPgfs endeavor (Geospatial Resource for Agricultural Species and Pests with integrated workflow modelling to support Global Food Security) between multiple disciplines around a common objective of facilitating research and model simulations for sustainable food security. Within this endeavor, the geospatial media has been the enabler for multidisciplinary research in crop modelling. Geospatial genetic-trait variations and associations with environmental forecasting were the main focus of the GRASPgfs. Designing the platform achieving this objective generated a transdisciplinary vision of modelling and forecasting for sustainable agriculture. Based on interoperability principles, seamless access as well as sharing for data, metadata and processing models, the design is described in this paper. This geospatial binding facilitates and supports new types of hypotheses and analysis as illustrated in the paper with a landscape genetic case study (bambara groundnut) and a crop disease modelling (eyespot disease). The approach and the eGRASP platform are generic enough to accommodate further complexity into the integrated modelling that this geospatial binding enables.

In Mediterranean regions drought is the major factor limiting spring barley and durum wheat grain yields. This study aimed to compare spring barley and durum wheat root and shoot responses to drought and quantify relationships between root traits and water uptake under terminal drought. One spring barley (Hordeum vulgare L. cv. Rum) and two durum wheat Mediterranean cultivars (Triticum turgidum L. var durum cvs Hourani and Karim) were examined in soil-column experiments under well watered and drought conditions. Root system architecture traits, water uptake, and plant growth were measured. Barley aerial biomass and grain yields were higher than for durum wheat cultivars in well watered conditions. Drought decreased grain yield more for barley (47%) than durum wheat (30%, Hourani). Root-to-shoot dry matter ratio increased for durum wheat under drought but not for barley, and root weight increased for wheat in response to drought but decreased for barley. The critical root length density (RLD) and root volume density (RVD) for 90% available water capture for wheat were similar to (cv. Hourani) or lower than (cv. Karim) for barley depending on wheat cultivar. For both species, RVD accounted for a slightly higher proportion of phenotypic variation in water uptake under drought than RLD.

SUMMARYThe effect of drought and temperature on the growth and development of bambara groundnut (Vigna subterranea (L.) Verdc.) was studied in controlled environment glasshouses in the United Kingdom. There were two landraces, S19-3 (from a hot, dry environment; Namibia) and Uniswa Red (from a cool, wet environment; Swaziland), two temperature regimes (23 °C and 33 °C) and three watering regimes (2006; fully irrigated), 2007 (drought imposed at 77 days after sowing (DAS)) and 2008 (drought imposed at 30 DAS)). Bambara groundnut responded to drought by slowing the rate of leaf area expansion and reducing final canopy size and total dry matter (TDM). Drought also caused significant reductions in pod dry matter, pod numbers and harvest index (HI), leading to a decrease in final yield that was different between landraces. Throughout the three growing seasons, landraces grown at 33 °C produced more TDM than the landraces grown at 23 °C. The two landraces differed in their phenology; S19-3 exhibited a reduced phenology where leaf numbers started to decrease before Uniswa Red at both temperatures, while Uniswa Red maintained the longest life cycle. The lowest pod yield was produced by Uniswa Red in 2008 at 33 °C (maximum of 35.5 gm−2), while S19-3 produced a minimum pod yield of 56.6 gm−2 at 33 °C, also in 2008. However, both landraces produced considerably more pod yield at 23 °C throughout the three growing seasons (minimum of 151 gm−2 and 162 gm−2 for Uniswa Red and S19-3, respectively). Under moderate drought, S19-3 at 33 °C gave the highest pod yield (365 gm−2) among the treatments throughout the three growing seasons and maintained HI better under drought. Despite being from a hot, dry environment, S19-3 also performed well at low temperature, which indicates the adaptation of S19-3 to low temperature that it also experiences in the country of origin.

Staple crops face major challenges in the near future and a diversification away from over-reliance on staples will be important as part of the progress towards the goal of achieving security of food production. Underutilized or neglected crops species are often indigenous ancient crop species which are still used at some level within the local, national or even international communities, but have the potential to contribute further to the mix of food sources than they currently do. The most cost-effective and easily disseminated changes that can be made to a crop are changes to the genetics, as these are contained within the seed itself and, for many species, the seed is a pure breeding, self-replicating, resource. This article focuses on the potential of underutilized crops to contribute to food security and, in particular, whether genetics and breeding can overcome some of the constraints to the enhanced uptake of these species in the future. The focus here is on overview rather than detail and subsequent articles will examine the current evidence base.

SUMMARYSimulation models for many crops are often simple, empirical equations that lack generality across different locations or different levels of abiotic stress making them difficult to apply by independent researchers. The objective of this paper is to describe and demonstrate a user-oriented model ‘BAMGRO’ for an underutilized crop, bambara groundnut with enough detail to be general across locations and genotypes but not so complex that independent users cannot apply it to their own situations. The model consists of different sub-modules that deal specifically with weather (thermal time), crop growth (canopy development, biomass production and yield), temperature (heat and cold stress), photoperiod (daylength control of phenology and reproductive development) and soil water (drought stress). The model predictions are achieved by defining genotype (i.e. cultivar) input files, daily weather parameters and soil characteristics. The model achieves a good fit between observed and predicted data for leaf area index (Nash and Sutcliffe (N-S), 0.80–0.84; mean absolute error (MAE) with maximum less than ± 0.50) for tested genotypes. Pod yield simulation correlated well with measured values (N-S 0.73–0.87; MAE ± 16 g m−2). Available soil moisture content correlated well with the observed data for a field site in Botswana indicating successful performance of the soil water module.

SUMMARYSimulation of yield response to water plays an increasingly important role in optimization of crop water productivity (WP) especially in prevalent drought in Africa. The present study is focused on a representative crop: bambara groundnut (Vigna subterranea), an ancient grain legume grown, cooked, processed and traded mainly by subsistence women farmers in sub-Saharan Africa. Over four years (2002, 2006–2008), glasshouse experiments were conducted at the Tropical Crops Research Unit, University of Nottingham, UK under controlled environments with different landraces, temperatures (23 ± 5 °C, 28 ± 5 °C, 33 ± 5 °C) and soil moisture regimes (irrigated, early drought, late drought). Parallel to this, field experiments were conducted in Swaziland (2002/2003) and Botswana (2007/2008). Crop measurements of canopy cover (CC), biomass (B) and pod yield (Y) of selected experiments from glasshouse (2006 and 2007) and field (Botswana) were used to calibrate the FAO AquaCrop model. Subsequently, the model was validated against independent data sets from glasshouse (2002 and 2008) and field (Swaziland) for different landraces. AquaCrop simulations for CC, B and Y of different bambara groundnut landraces are in good agreement with observed data with R2 (CC-0.88; B-0.78; Y-0.72), but with significant underestimation for some landraces.

Genetic diversity of a Bambara groundnut germplasm representing accessions from 25 African countries, maintained at the International Institute of Tropical Agriculture (IITA; Nigeria) was evaluated based on seed patterns, qualitative characters, quantitative traits and Diversity Arrays Technique (DArT) markers. The study aimed at identifying important descriptors for germplasm conservation, validating the crop’s geographical centre of origin and facilitating the utilization of existing genetic resources. Frequencies and diversity indices of seven types of seed patterns, 12 qualitative and 28 quantitative traits were evaluated for 124 representative accessions and were analyzed by region to elucidate the geographic distribution of descriptor states. In addition, individual plant samples from a subset of 40 landrace accessions were analyzed by assessing 554 DArT markers. Both the phenetic tree constructed from the qualitative and quantitative descriptors and the population structure derived from DArT marker analysis suggested a relatively high genetic diversity among accessions. Higher genetic diversity was observed for the Cameroon/Nigeria region relative to other regions, in agreement with the hypothesis that this region is the centre of origin for Bambara groundnut. Use of an extensive and diverse range of germplasm and an approach that integrated morphological and quantitative descriptors with DNA markers that represent wide genomic coverage offered a powerful way to make inferences about crop germplasm, in support of crop-improvement programs.

SUMMARYThe association of carbon isotope discrimination of grain (Δ13C) with yield performance under rain-fed and well-watered conditions was analysed using a doubled-haploid (DH) winter wheat population, derived from the cross between cvars Beaver×Soissons, within field experiments at two site-seasons. The aim of this work was to quantify associations between Δ13C and yield responses to drought and to test effects of major genes (the semi-dwarf genes, Rht-B1b, Rht-D1b, an awn suppressor gene, B1 and the 1BL.1RS wheat–rye chromosome translocation) segregating in the population for associations with Δ13C and drought performance. Carbon isotope discrimination, through its negative relationship with transpiration efficiency, may be used as a surrogate for this trait. Grain Δ13C was positively associated with grain yield under both irrigated and unirrigated conditions in each site-season and, overall, explained 0·34 of the phenotypic variation in grain yield amongst DH lines under drought and 0·14 under well-watered conditions. There was a positive association between specific leaf lamina N content (SLN) at anthesis and Δ13C under drought amongst DH lines in one site-season, suggesting higher SLN may confer increased stomatal conductance via higher photosynthetic capacity, hence increased grain Δ13C. Overall the Rht-D1b (semi-dwarf) lines had slightly higher Δ13C of grain (20·0‰) than the Rht-B1a/Rht-D1a (tall) group of lines (19·8‰). There were no significant differences between the Rht-B1b (semi-dwarf) or the Rht-B1b/Rht-D1b (dwarf) lines and the tall lines. Comparing their performance under irrigated and unirrigated conditions, the Rht groups of lines (Rht-B1b semi-dwarf, Rht-D1b semidwarf and dwarf and tall groups) responded no differently to drought for Δ13C. The Rht-D1b semi-dwarf lines had higher grain yield (9·50 t/ha) than the tall lines (8·76 t/ha), while the yield of the Rht-B1b semi-dwarf and dwarf lines did not differ significantly from the tall lines. In each site-season, the presence of the 1BL.1RS chromosome increased grain Δ13C (PP13C was not statistically significant in either site-season. Overall, the present results show that Rht-D1b confers higher Δ13C and grain yield, and the 1BL.1RS translocation confers higher Δ13C. This implies that modern UK wheat cultivars may have lower water-use efficiency during the grain filling period than their predecessors, and therefore may require more water to fulfil their yield potential.

Canopy development of bambara groundnut (Vigna subterranea (L.) Verdc) is affected by temperature stress, drought stress and photoperiod. The quantification of these documented effects by means of a suitable crop model, BAMGRO is presented in this paper. Data on canopy development from five growth chamber, four glasshouse and three field experiments were analyzed to calibrate and validate the BAMGRO model to produce simulations for temperature stress, drought stress and photoperiodic effect on two contrasting landraces; Uniswa Red (Swaziland) and S19-3 (Namibia). The daily initiation rate of new leaves is calculated by means of a Gaussian function and is altered by temperature stress, drought stress, photoperiod and plant density. The rate in dead leaf number is dependent upon the maximum senescence fraction which can be explained by physiological maturity, mutual shading, temperature stress and drought stress. The leaf area expansion is calculated as a function of leaf number and individual leaf size. The canopy development of bambara groundnut is modelled (and tested) in BAMGRO model by means of leaf initiation and leaf area expansion and branching and stem production are not considered. Nash and Sutcliffe value (N–S) is used as the measure of the mean square error to the observed variance. The simulated leaf number per plant correlated well with the glasshouse measurements for Uniswa Red for the two considered years (2007 and 2008) with high N–S value (Nash and Sutcliffe; from 0.76 to 0.92), low mean absolute error (MAE; from ±2.91 to 3.98) and Botswana field grown in January 18 and February 1, 2007 (N–S, 0.88 and 0.74; MAE, ±0.59 and ±6.18). Overall, simulated LAI correlated well with measured values for the two tested landraces; S19-3 (N–S value, 0.84) and Uniswa Red (N–S value, 0.80) with maximum MAE less than ±0.50 thus explaining canopy development under temperature stress, drought stress and variable photoperiods.

This study involves an assessment of the potential effects of greenhouse gas climate change, as well as the direct fertilization effect of CO2 on crop yields in Cameroon. The methodology involves coupling the transient diagnostics of 2 atmosphere-ocean general circulation models, namely NASA/Goddard Institute GISS and the Hadley Centre's HadCM3, to the CropSyst crop model to simulate current and future (2020, 2080) crop yields (bambara nut, groundnut, maize, sorghum and soybean) in 8 agricultural regions of Cameroon. For the future we estimate substantial yield increases for bambara groundnut, soybean and groundnut, and little or no change and even decreases of maize and sorghum yields, varying according to the climate scenario and the agricul- tural region. Maize and sorghum (both C4 crops) yields are expected to decrease by 14.6 and 39.9%, respectively, across the whole country under GISS 2080 scenarios. The results also show that the effect of temperature patterns on climate change is much more important than that of precipitation. Findings call for monitoring of climate change/variability and dissemination of information to farmers, to encourage adaptation to climate change.

The effect of drought on the growth and development of bambara groundnut (Vigna subterranea (L.) Verdc.) was studied in controlled-environment glasshouses in the UK. There were three landraces (S19-3, DipC and UN from Namibia, Botswana and Swaziland, respectively) and two watering regimes; a control that was irrigated weekly to 90% field capacity and a drought treatment with no irrigation from 49 days after sowing (DAS) until final harvest (147 DAS). Bambara groundnut responded to drought by reducing the rate of leaf area expansion, final canopy size and total dry matter (TDM) during vegetative growth. Drought also caused significant reductions in pod dry matter (PDM), pod number, seed weight and harvest index (HI), leading to a decrease in final pod yield that was different between landraces. Across landraces, drought reduced mean pod yield from 298 g m−2 to 165 g m−2, representing 45% yield loss. Despite the reduction in all landraces, the mean pod yield across the droughted treatments that had received no water for almost 100 days indicated the resilience of the species to drought. The three landraces differed in their phenology; S19-3 exhibited a reduced phenology while UN maintained the longest life cycle. The different responses of the landraces reflect their adaptation to their local climates where mean annual rainfall ranges between 365 mm (Namibia) and 1390 mm (Swaziland). We discuss the significance of these results for future breeding programmes on bambara groundnut.

Controlled crosses in bambara groundnut were attempted between a range of thirty-six bambara groundnut landraces (thirty domesticated (V. subterranea var. subterranea) and six wild (V. subterranea var. spontanea)). Ten F-1 seed were produced. Of these, eight germinated producing F-2 populations. On seed set, four populations could be unambiguously confirmed as true crosses by F-3 seed coat colour. A single F-2 population, derived from a domesticated landrace from Botswana (DipC; female parent) crossed with a wild accession collected in Cameroon (VSSP11; male parent) was used to study a range of agronomic and domestication traits. These included; days to emergence, days to flowering, internode (fourth) length at harvest, number of stems per plant, leaf area, Specific Leaf Area (SLA), Carbon Isotope Discrimination (CID), 100 seed weight, testa colour and eye pattern around the hilum. On the basis of variation for internode length and stems per plant, 14 small F-3 families were selected and grown under field conditions to further investigate the genetic basis of the 'spreading' versus 'bunched' plant character, a major difference between wild and cultivated bambara groundnut. Results presented suggest that traits including leaf area, SLA, CID and 100 seed weight are controlled by several genes. In contrast, the variation for traits such as internode length, stems per plant, days to emergence and seed eye pattern around the hilum are likely to be under largely monogenic control. The results of this work are discussed in relation to the domestication of bambara groundnut.

A study was conducted to compare the performance of the PR1 capacitance probe (Delta-T Devices) in measuring soil volumetric moisture content (θ) with two established standard methods: the neutron probe (Didcot Instruments) and the gravimetric method. Over a two-year period, the three methods were used to measure θ in glasshouse plots containing crops of either oilseed rape (Brassica napus L.) or bambara groundnut (Vigna subterranea L.). The PR1 probe gave variable performance depending on the depth and soil profile where the measurements were made. In most cases, the PR1 probe significantly overestimated θ. In some cases, it significantly underestimated θ or gave similar values to the other methods. Despite this frequent overestimation of θ, the PR1 probe adequately registered the relative changes in θ Its measurements were linearly and positively related to those of the gravimetric and neutron-probe methods. However, the regression lines significantly deviated from the 1:l line. This paper discusses the possible reasons for the unsatisfactory performance of the PR1 probe and the practical problems associated with the installation of its access tubes.

Ten bambara groundnut [Vigna subterranea (L.) Verdc] landraces of diverse origin were used to examine the effect of temperature on the rate of leaf appearance (RLA) and to determine the base temperature (T b ) among landraces. Knowledge of leaf development is required in breeding programs where crop morphological development is considered an important selection criterion. The ability to predict leaf appearance would also facilitate modeling of plant development. Plants were grown in controlled-environment growth rooms under different temperatures (20, 25, 30, 32, and 35°C ± 1). The study to examine the effect of temperature on leaf appearance in bambara groundnut landraces indicated that the base temperature (T b ) for leaf appearance ranged from 8.1 to 12.0°C. Within the range of temperatures evaluated in this study, the observation of differences in T b values among the landraces suggests that T b values for leaf appearance are landrace dependent. The phyllochron was also variable among landraces ranging from 40.9 to 53.0°C. The RLA ranged from 0.19 to 0.63 leaves d -1 depending on temperature and landrace. The landrace variations in relation to leaf appearance may allow selection of landraces for different environments.

Genetic diversity in 12 landraces of bambara groundnut (Vigna subterranea), an indigenous African legume, was evaluated using Random Amplified Polymorphic DNA (RAPD) markers. DNA from individuals of each landrace was also analysed to determine the level of heterogeneity within landraces. RAPDs revealed high levels of polymorphism among landraces. The percentage polymorphism ranged from 63.2% to 88.2% with an average of 73.1% for the 16 RAPD primers evaluated. The construction of genetic relationships using cluster analysis groups the 12 landraces in two clusters. RAPDs are useful for the genetic diversity studies in V. subterranea and can identify variation within landraces.

Bambara groundnut (Vigna subterranea (L.) Verdc), an African indigenous legume, is popular in most parts of Africa. The present study was undertaken to establish genetic relationships among 16 cultivated bambara groundnut landraces using fluorescence-based amplified fragment length polymorphism (AFLP) markers. Seven selective primer combinations generated 504 amplification products, ranging from 50 to 400 bp. Several landrace-specific products were identified that could be effectively used to produce landrace-specific markers for identification purposes. On average, each primer combination generated 72 amplified products that were detectable by an ABI Prism 310 DNA sequencer. The polymorphisms obtained ranged from 68.0 to 98.0%, with an average of 84.0%. The primer pairs M-ACA + P-GCC and M-ACA + P-GGA produced more polymorphic fragments than any other primer pairs and were better at differentiating landraces. The dendrogram generated by the UPGMA (unweighted pair-group method with arithmetic averaging) grouped 16 landraces into 3 clusters, mainly according to their place of collection or geographic origin. DipC1995 and Malawi5 were the most genetically related landraces. AFLP analysis provided sufficient polymorphism to determine the amount of genetic diversity and to establish genetic relationships in bambara groundnut landraces. The results will help in the formulation of marker-assisted breeding in bambara groundnut.Key words: under-utilized, African legume, molecular markers.

Stands of groundnut (Arachis hypogaea L. cv. Kadiri-3) were grown in controlled environment glasshouses at mean atmospheric CO 2 concentrations of 375 or 700 μmol mol -1 and daily mean air temperatures of 28 or 32°C on irrigated or drying soil profiles. Leaf water (Ψ 1 ) and solute potential (Ψ s ), relative water content (RWC), stomatal conductance (g,) and net photosynthesis (P n ) were measured at midday for the youngest mature leaf throughout the growing season. Elevated CO 2 and temperature had no detectable effect on the water relations of irrigated plants, but higher values of RWC, Ψ 1 and Ψ s were maintained for longer under elevated CO 2 during progressive drought. Turgor potential (Ψ p ) reached zero when Ψ 1 declined to -1.6 to - 1.8 MPa in all treatments; turgor was lost sooner when droughted plants were grown under ambient CO 2 . A 4°C increase in mean air temperature had no effect on Ψ s in droughted plants, but elicited a small increase in Ψ 1 ; midday g 1 values were lower under elevated than under ambient CO 2 , and Ψ 1 and g, declined below - 1.5 MPa and 0.25 cm s -1 , respectively, as the soil dried. Despite the low g 1 values recorded for droughted plants late in the season, P n was maintained under elevated CO 2 , but declined to zero 3 weeks before final harvest under ambient CO 2 . Concurrent reductions in g, and increases in water use efficiency under elevated CO 2 prolonged photosynthetic activity during drought and increased pod yields relative to plants grown under ambient CO 2 . The implications of future increases in atmospheric CO 2 for the productivity of indeterminate C 3 crops grown in rainfed subsistence agricultural systems in the semi-arid tropics are discussed.

Three landraces of bambara groundnut (Vigna subterranea (L.) Verdc.) were grown as crop stands in controlled environment glasshouses at the Tropical Crops Research Unit, University of Nottingham, in 1995. Two soil moisture treatments were imposed: irrigated to 90% field capacity each week and irrigated to 60% field capacity until establishment (27 days after sowing) with no further irrigation. Seasonal mean fractional interception varied between 0·20–0·37 for the droughted treatments and 0·62–0·74 for the irrigated treatments, resulting in cumulative intercepted radiation of 228–350 MJ/m2 and 662–794 MJ/m2, respectively. The maximum total dry matter (DM) produced was 5·8 t/ha at final harvest (145 days after sowing) with a pod yield of 2·7 t/ha. Under moisture stress there was little difference in DM production between landraces, with the highest total DM of 1·1 t/ha and a pod yield of 0·05 t/ha, representing a harvest index of 0·05 compared with an average of 0·46 for the irrigated treatments. The conversion coefficient was reduced from 1·00 under irrigation to 0·51 g DM/MJ radiation intercepted by soil moisture stress. Two of the landraces showed adaptive mechanisms to avoid drought; these are discussed in relation to maximizing seasonal radiation interception.

Bambara groundnut is an indigenous African legume crop plant. It is largely grown by subsistence farmers, but can also be used as a cash crop to supplement family income. The fact that it is highly drought tolerant means that it has considerably potential to provide part of food security in regions of the world where water availability is a serious issue. As one part of the international effort to understand and improve this species, we report here the first 10 microsatellite markers derived from bambara groundnut.

The components of leaf water potential (Ψ I ) and relative water content (RWC) were measured for stands of bambara groundnut (Vigna subterranea) exposed to three soil moisture regimes in controlled-environment glasshouses at the Tropical Crops Research Unit, Sutton Bonington Campus. Treatments ranged from fully irrigated (wet) to no irrigation from 35 days after sowing (DAS) (dry). RWC values varied between 92-96% for the wet treatment, but declined from 93% to 83% in the dry treatment as the season progressed. Ψ I at midday decreased in both the wet and dry treatments, but the seasonal decline was more pronounced in the latter: seasonal minimum values were -1.19 and - 2.08 MPa, respectively. Plants in the wet treatment maintained turgor (Ψ p ) at about 0.5 MPa throughout the season, whereas values in the dry treatment approached zero towards the end of the season. There was a linear relationship between Ψ p and Ψ I , with Ψ p approaching zero at a Ψ I of -2.0 MPa. Mean daily leaf conductance was consistently higher in the wet treatment (0.46-0.79 cm s -1 ) than in the intermediate and dry treatments (0.13-0.48 cm s -1 ). Conductances in the intermediate and dry treatments were similar, and the lower evapotranspirational water losses in the latter were attributable to its consistently lower leaf area indices (L): L at final harvest was 3.3, 3.3 and 1.9 for the wet, intermediate and dry treatments. Bambara groundnut was apparently able to maintain turgor through a combination of osmotic adjustment, reductions in leaf area index and effective stomatal regulation of water loss.

In Mediterranean regions drought is the major factor limiting spring barley and durum wheat grain yields. This study aimed to compare spring barley and durum wheat root and shoot responses to drought and quantify relationships between root traits and water uptake under terminal drought. One spring barley (Hordeum vulgare L. cv. Rum) and two durum wheat Mediterranean cultivars (Triticum turgidum L. var durum cvs Hourani and Karim) were examined in soil-column experiments under well watered and drought conditions. Root system architecture traits, water uptake, and plant growth were measured. Barley aerial biomass and grain yields were higher than for durum wheat cultivars in well watered conditions. Drought decreased grain yield more for barley (47%) than durum wheat (30%, Hourani). Root-to-shoot dry matter ratio increased for durum wheat under drought but not for barley, and root weight increased for wheat in response to drought but decreased for barley. The critical root length density (RLD) and root volume density (RVD) for 90% available water capture for wheat were similar to (cv. Hourani) or lower than (cv. Karim) for barley depending on wheat cultivar. For both species, RVD accounted for a slightly higher proportion of phenotypic variation in water uptake under drought than RLD.

A number of novel strategies were employed to examine the role of indoleacetic acid (IAA) in regulating floral organ abscission in Arabidopsis (Arabidopsis thaliana). Analysis of auxin influx facilitator expression in β-glucuronidase reporter plants revealed that AUXIN RESISTANT1, LIKE AUX1, and LAX3 were specifically up-regulated at the site of floral organ shedding. Flowers from mutants where individual family members were down-regulated exhibited a reduction in the force necessary to bring about petal separation; however, the effect was not additive in double or quadruple mutants. Using the promoter of a polygalacturonase (At2g41850), active primarily in cells undergoing separation, to drive expression of the bacterial genes iaaL and iaaM, we have shown that it is possible to manipulate auxin activity specifically within the floral organ abscission zone (AZ). Analysis of petal breakstrength reveals that if IAA AZ levels are reduced, shedding takes place prematurely, while if they are enhanced, organ loss is delayed. The At2g41850 promoter was also used to transactivate the gain-of-function AXR3-1 gene in order to disrupt auxin signaling specifically within the floral organ AZ cells. Flowers from transactivated lines failed to shed their sepals, petals, and anthers during pod expansion and maturity, and these organs frequently remained attached to the plant even after silique desiccation and dehiscence had taken place. These observations support a key role for IAA in the regulation of abscission in planta and reveal, to our knowledge for the first time, a requirement for a functional IAA signaling pathway in AZ cells for organ shedding to take place.

SUMMARYStands of bambara groundnut (Vigna subterranea (L.) Verde.) were grown in five controlledenvironment glasshouses at the Tropical Crops Research Unit, University of Nottingham, Sutton Bonington Campus, in 1990. Five soil moisture regimes were imposed (one per house), from fully irrigated each week (treatment A), to no irrigation after crop establishment at 35 days after sowing (DAS) (treatment E). Decreasing the amount of water applied resulted in a decline in total dry matter production and harvest index, and a reduction in pod yield from 412 (treatment B) to 0·041 ha-1 (treatment E) at 125 DAS. A maximum leaf area index of 5–4 was achieved by treatments B and C at 90 DAS, resulting in a fractional interception of c. 0·8 of incoming radiation. Total accumulated radiation interception values were 749, 693, 688, 618 and 554 MJ m-2 for treatments A, B, C, D and E, respectively. The efficiency of conversion of the radiation intercepted into dry matter was reduced from 1·41 to 0·50 g MJ-1 by drought.

The effects of elevated atmospheric CO 2 , alone or in combination with water stress, on stomatal frequency in groundnut (Arachis hypogaea (L.) cv. Kadiri-3) were investigated. CO 2 exerted significant effects on stomatal frequency only in irrigated plants. The effects of drought on leaf development outweighed the smaller effects of CO 2 concentration, although reductions in stomatal frequency induced by elevated atmospheric CO 2 were still observed. When stands of groundnut were grown under irrigated conditions with unrestricted root systems, an increase in atmospheric CO 2 from 375 to 700 ppmv decreased stomatal frequency on both leaf surfaces by up to 16%; in droughted plants, stomatal frequency was reduced by 8% on the adaxial leaf surface only. Elevated atmospheric CO 2 promoted larger reductions in leaf conductance than the changes in stomatal frequency, indicating partial stomatal closure. As a result, the groundnut stands grown at elevated CO 2 utilized the available soil moisture more slowly than those grown under ambient CO 2 , thereby extending the growing period. Despite the large variations in cell frequencies induced by drought, there was no treatment effect on either stomatal index or the adaxial/abaxial stomatal frequency ratio. The data suggest that the effects of future increases in atmospheric CO 2 concentration on stomatal frequency in groundnut are likely to be small, especially under conditions of water stress, but that the combination of associated reductions in leaf conductance and enhanced assimilation at elevated CO 2 will be important in semi-arid regions.

Stands of groundnut (Arachis hypogaea L. cv. Kadiri 3) were grown in controlled environment glasshouses at two mean air temperatures (28° C and 32° C), two atmospheric CO 2 concentrations (371 ppmv and 700 ppmv) and two soil moisture treatments (irrigated weekly to field capacity or allowed to dry from 22 d after sowing). The transpiration equivalent, Ω w (g kPa kg −1 ) - the product of the accumulated biomass/transpired water ratio and the saturation deficit - was calculated for all the treatments using above-ground harvest, root core and neutron probe measurements. Neither temperature nor soil moisture treatment was found to have an effect on Ω w

SUMMARYBambara groundnut (Vigna subterranea (L.) Verde.) is grown throughout southern and western Africa, primarily as a subsistence crop, but agronomic information is scarce. The rates of emergence, flowering and pod production were assessed for 20 weekly sowings between 16 October 1990 and 26 February 1991 at Sebele, Gaborone, Botswana. Daylength during this period changed from 12·7 h to 13·7 h and back to 12·6 h. Mean time to 50% emergence was 111 days while mean time to 50% flowering was 47·5 days. The thermal time to first pod production varied with daylength, decreasing as daylength decreased, to an approximately constant value when daylength after flowering was less than about 12 h. Consequently, the plant size at which pods were produced also varied. The practical implications for date of sowing and plant spacing are discussed.