A substantial increase in grain yield potential is required, along with better use of water and fertilizer, to ensure food security and environmental protection in future decades. For improvements in ...photosynthetic capacity to result in additional wheat yield, extra assimilates must be partitioned to developing spikes and grains and/or potential grain weight increased to accommodate the extra assimilates. At the same time, improvement in dry matter partitioning to spikes should ensure that it does not increase stem or root lodging. It is therefore crucial that improvements in structural and reproductive aspects of growth accompany increases in photosynthesis to enhance the net agronomic benefits of genetic modifications. In this article, six complementary approaches are proposed, namely: (i) optimizing developmental pattern to maximize spike fertility and grain number, (ii) optimizing spike growth to maximize grain number and dry matter harvest index, (iii) improving spike fertility through desensitizing floret abortion to environmental cues, (iv) improving potential grain size and grain filling, and (v) improving lodging resistance. Since many of the traits tackled in these approaches interact strongly, an integrative modelling approach is also proposed, to (vi) identify any trade-offs between key traits, hence to define target ideotypes in quantitative terms. The potential for genetic dissection of key traits via quantitative trait loci analysis is discussed for the efficient deployment of existing variation in breeding programmes. These proposals should maximize returns in food production from investments in increased crop biomass by increasing spike fertility, grain number per unit area and harvest index whilst optimizing the trade-offs with potential grain weight and lodging resistance.
Nitrification, a key process in the global nitrogen cycle that generates nitrate through microbial activity, may enhance losses of fertilizer nitrogen by leaching and denitrification. Certain plants ...can suppress soil-nitrification by releasing inhibitors from roots, a phenomenon termed biological nitrification inhibition (BNI). Here, we report the discovery of an effective nitrification inhibitor in the root-exudates of the tropical forage grass Brachiaria humidicola (Rendle) Schweick. Named "brachialactone," this inhibitor is a recently discovered cyclic diterpene with a unique 5-8-5-membered ring system and a γ-lactone ring. It contributed 60-90% of the inhibitory activity released from the roots of this tropical grass. Unlike nitrapyrin (a synthetic nitrification inhibitor), which affects only the ammonia monooxygenase (AMO) pathway, brachialactone appears to block both AMO and hydroxylamine oxidoreductase enzymatic pathways in NITROSOMONAS: Release of this inhibitor is a regulated plant function, triggered and sustained by the availability of ammonium (NHFormula: see text) in the root environment. Brachialactone release is restricted to those roots that are directly exposed to NHFormula: see text. Within 3 years of establishment, Brachiaria pastures have suppressed soil nitrifier populations (determined as amoA genes; ammonia-oxidizing bacteria and ammonia-oxidizing archaea), along with nitrification and nitrous oxide emissions. These findings provide direct evidence for the existence and active regulation of a nitrification inhibitor (or inhibitors) release from tropical pasture root systems. Exploiting the BNI function could become a powerful strategy toward the development of low-nitrifying agronomic systems, benefiting both agriculture and the environment.
A genetic analysis of plant characters associated with lodging resistance, yield and other agronomic traits was made on two doubled haploid winter wheat populations grown at two UK locations in the ...2004/2005, 2005/2006 and 2006/2007 seasons. Wide genetic variation was found for traits that affect lodging, including plant height, components of stem strength (stem diameter, wall width and material strength), components of anchorage strength (spread and depth of the root plate), ear area and shoot number per plant. Heritabilities were estimated for each of the key lodging traits, with plant height having the highest heritability and anchorage traits the lowest values. Six quantitative trait loci (QTL) controlling plant height had individual height effects (2 × the additive effect) of 3–9 cm and taken together, could potentially increase plant height by up to 34 cm. Three of the height QTL were also associated with greater yield or greater thousand grain weight, and three were associated with components of stem strength or anchorage strength. QTL were also identified for each of the measured lodging traits, which were unrelated to height. Individual QTL with the largest estimated effects on lodging resistance were for height, stem diameter, stem material strength, stem failure moment, root plate spread and root plate depth. Diagnostic genetic markers for the most important QTL regions are now required to enable breeders to efficiently combine multiple traits together in a single variety that will increase lodging resistance and yield simultaneously.
•Genetic variation for lodging related properties of spring wheat under North-wet Mexico growing conditions.•Heritability of lodging related properties.•Implications of achieving a lodging resistant ...crop with current genetic variation of wheat.
Lodging-related traits were evaluated on the CIMMYT Core spring wheat Germplasm Panel (CIMCOG) in the Yaqui Valley of North-West Mexico during three seasons (2010–2013). Genetic variation was significant for all the lodging-related traits in the cross-year analysis, however, significant G×E interaction due to rank changes or changes in the absolute differences between cultivars were identified. The inconsistences on cultivar performances across seasons particularly reduced the heritability of key characters related to root lodging resistance (anchorage strength). Target characters related to stem lodging resistance (stem strength) showed good heritability values equal or above 0.70. Positive correlations between stem strength and stem diameter and between root plate spread and root strength were found. Selecting for greater stem diameter and wall width, greater root plate spread and shorter plant height could enable breeders to increase lodging resistance by increasing stem strength, root strength and decreasing plant leverage, respectively. Achieving a lodging-proof crop will depend on finding a wider root plate spread and implementing new management strategies. Genetic linkages between lodging traits will not constrain the combination of the key lodging-trait dimensions to achieve a lodging-proof ideotype. However, strong association between stem strength and stem wall width will increase the total biomass cost needed for lodging resistance.
•Use of an existing model for lodging resistance on spring wheat growing in North-West Mexico.•Structural properties of a lodging-proof crop able to resist lodging for a period of years in North-West ...Mexico.•Biomass cost for increasing lodging resistance (support structures).•Implications for breeding a lodging resistant crop.
A model of the lodging process has been successfully adapted for use on spring wheat grown in North-West Mexico (NWM). The lodging model was used to estimate the lodging-associated traits required to enable spring wheat grown in NWM with a typical yield of 6tha−1 and plant height of 0.7m to achieve a lodging return period of 25 years. Target traits included a root plate spread of 51mm and stem strength of the bottom internode of 268Nmm. These target traits increased to 54.5mm and 325Nmm, respectively, for a crop yielding 10tha−1. Analysis of multiple genotypes across three growing seasons enabled relationships between both stem strength and root plate spread with structural dry matter to be quantified. A NWM lodging resistant ideotype yielding 6tha−1 would require 3.93tha−1 of structural stem biomass and 1.10tha−1 of root biomass in the top 10cm of soil, which would result in a harvest index (HI) of 0.46 after accounting for chaff and leaf biomass. A crop yielding 10tha−1 would achieve a HI of 0.54 for 0.7m tall plants or 0.41 for more typical 1.0m tall plants. This study indicates that for plant breeders to achieve both high yields and lodging-proofness they must either breed for greater total biomass or develop high yielding germplasm from shorter crops.
Quantitative participatory exploration of the many complex issues surrounding cross-sectoral climate change impacts, vulnerability and adaptation under uncertain futures is dependent on the ...provision, in some form, of scenarios and scenario outputs. However, the normal provision by the research community of pre-defined scenario outputs results in a lack of flexibility for stakeholders regarding choice of climate models, scenarios, scenario quantification and output indicators which in turn can lead to a lack of trust. This Special Issue describes the development and application of a web-based interactive simulation and display environment, called the CLIMSAVE Integrated Assessment (IA) Platform, which provides a holistic (cross-sectoral, climate and socio-economic change) modelling framework. The IA Platform guides the user through simulation of (1) potential impacts under scenarios of climate and/or socio-economic change, (2) identification of sectoral and multi-sectoral vulnerability ‘hotspots’ either before or after adaptation, (3) the potential for adaptation to reduce impacts within the capital constraints of the selected scenario(s), and (4) the cost-effectiveness of adaptation measures. The Special Issue explores how the IA Platform has been: (i) designed to provide a user-friendly, intuitive and facilitating, rather than predictive or prescriptive, environment for users; and (ii) utilised to quantitatively explore a diverse range of uncertain futures across Europe.
Concurrent hip and spine pathologies can alter the biomechanics of spinopelvic mobility in primary total hip arthroplasty (THA). This study examines how differences in pelvic orientation of patients ...with spine fusions can increase the risk of dislocation risk after THA.
We identified 84 patients (97 THAs) between 1998 and 2015 who had undergone spinal fusion prior to primary THA. Patients were stratified into three groups depending on the length of lumbar fusion and whether or not the sacrum was involved. Mean age was 71 years (40 to 87) and 54 patients (56%) were female. The mean body mass index (BMI) was 30 kg/m
(19 to 45). Mean follow-up was six years (2 to 17). Patients were 1:2 matched to patients with primary THAs without spine fusion. Hazard ratios (HR) were calculated.
Dislocation in the fusion group was 5.2% at one year versus 1.7% in controls but this did not reach statistical significance (HR 1.9; p = 0.33). Compared with controls, there was no significant difference in rate of dislocation in patients without a sacral fusion. When the sacrum was involved, the rate of dislocation was significantly higher than in controls (HR 4.5; p = 0.03), with a trend to more dislocations in longer lumbosacral fusions. Patient demographics and surgical characteristics of THA (i.e. surgical approach and femoral head diameter) did not significantly impact risk of dislocation (p > 0.05). Significant radiological differences were measured in mean anterior pelvic tilt between the one-level lumbar fusion group (22°), the multiple-level fusion group (27°), and the sacral fusion group (32°; p < 0.01). Ten-year survival was 93% in the fusion group and 95% in controls (HR 1.2; p = 0.8).
Lumbosacral spinal fusions prior to THA increase the risk of dislocation within the first six months. Fusions involving the sacrum with multiple levels of lumbar involvement notably increased the risk of postoperative dislocation compared with a control group and other lumbar fusions. Surgeons should take care with component positioning and may consider higher stability implants in this high-risk cohort.
Satellite radar altimetry can be used to monitor surface water levels from space. While current and past altimetry missions were designed to study oceans, retracking the waveforms returned over land ...allows data to be retrieved for smaller water bodies or narrow rivers. The objective of this study is the assessment of the potential for river monitoring from radar altimetry in terms of water level and discharge in the Zambezi River basin. Retracked Envisat altimetry data were extracted over the Zambezi River basin using a detailed river mask based on Landsat imagery. This allowed for stage measurements to be obtained for rivers down to 80 m wide with an RMSE relative to in situ levels of 0.32 to 0.72 m at different locations. The altimetric levels were then converted to discharge using three different methods adapted to different data-availability scenarios: first with an in situ rating curve available, secondly with one simultaneous field measurement of cross-section and discharge, and finally with only historical discharge data available. For the two locations at which all three methods could be applied, the accuracies of the different methods were found to be comparable, with RMSE values ranging from 4.1 to 6.5% of the mean annual in situ gauged amplitude for the first method and from 6.9 to 13.8% for the second and third methods. The precision obtained with the different methods was analyzed by running Monte Carlo simulations and also showed comparable values for the three approaches with standard deviations found between 5.7 and 7.2% of the mean annual in situ gauged amplitude for the first method and from 8.7 to 13.0% for the second and third methods.
It is widely accepted that climate change poses severe threats to freshwater ecosystems. Here we examine the scientific basis for adaptively managing vulnerable habitats and species. Our views are ...shaped by a literature survey of adaptation in practice, and by expert opinion. We assert that adaptation planning is constrained by uncertainty about evolving climatic and non-climatic pressures, by difficulties in predicting species- and ecosystem-level responses to these forces, and by the plasticity of management goals. This implies that adaptation measures will have greatest acceptance when they deliver multiple benefits, including, but not limited to, the amelioration of climate impacts. We suggest that many principles for biodiversity management under climate change are intuitively correct but hard to apply in practice. This view is tested using two commonly assumed doctrines: “increase shading of vulnerable reaches through tree planting” (to reduce water temperatures); and “set hands off flows” (to halt potentially harmful abstractions during low flow episodes). We show that the value of riparian trees for shading, water cooling and other functions is partially understood, but extension of this knowledge to water temperature management is so far lacking. Likewise, there is a long history of environmental flow assessment for allocating water to competing uses, but more research is needed into the effectiveness of ecological objectives based on target flows. We therefore advocate more multi-disciplinary field and model experimentation to test the cost-effectiveness and efficacy of adaptation measures applied at different scales. In particular, there is a need for a major collaborative programme to: examine natural adaptation to climatic variation in freshwater species; identify where existing environmental practice may be insufficient; review the fitness of monitoring networks to detect change; translate existing knowledge into guidance; and implement best practice within existing regulatory frameworks.
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