• Energy Research

Abstract Source traits are currently of great interest for the enhancement of yield potential; for example, much effort is being expended to find ways of modifying photosynthesis. However, photosynthesis is but one component of crop regulation, so sink activities and the coordination of diverse processes throughout the crop must be considered in an integrated, systems approach. A set of ‘wiring diagrams’ has been devised as a visual tool to integrate the interactions of component processes at different stages of wheat development. They enable the roles of chloroplast, leaf, and whole-canopy processes to be seen in the context of sink development and crop growth as a whole. In this review, we dissect source traits both anatomically (foliar and non-foliar) and temporally (pre- and post-anthesis), and consider the evidence for their regulation at local and whole-plant/crop levels. We consider how the formation of a canopy creates challenges (self-occlusion) and opportunities (dynamic photosynthesis) for components of photosynthesis. Lastly, we discuss the regulation of source activity by feedback regulation. The review is written in the framework of the wiring diagrams which, as integrated descriptors of traits underpinning grain yield, are designed to provide a potential workspace for breeders and other crop scientists that, along with high-throughput and precision phenotyping data, genetics, and bioinformatics, will help build future dynamic models of trait and gene interactions to achieve yield gains in wheat and other field crops.

The realisation of the full objectives of international policies targeting global food security and climate change mitigation, including the European Green Deal, United Nation’s Sustainable Development Goals (SDGs), the Paris Climate Agreement COP21 and transition away from a fossil-carbon industrial base to one that is more bio-based, requires that we (i) sustainably increase the yield, nutritional quality, and biodiversity of major crop species, (ii) select climate-ready crops that are adapted to future weather dynamic and (iii) increase the resource use efficiency of crops to preserve natural resources, such as fresh water and phosphate and reducing the environmental burden arising from the application of nitrogenous fertiliser. Advanced scientific knowledge and tools for research and crop breeding already provide an excellent platform to build on. A long-term Strategic Research Agenda now needs to be agreed and priorities set to deliver blueprints for climate resilient future-proofed crops. This strategy should then be implemented through an innovative collaborative approach that combines the joint knowledge base of the research and industrial communities, with multi-stakeholder involvement and strong support from policy makers. This white paper has been compiled from contributions from several experts across the field of plant sciences. The CropBooster-P project has developed this strategic research agenda for a crop improvement programme that will provide the genetic innovation to improve and future proof our crop plants. It builds a strong collaboration between plant scientists and modellers, physicists, soil scientists, engineers and coders, biomathematicians, agronomists, plant breeders and farmers. The goal is to exploit the largely untapped genetic diversity that exists within the wild relatives and ancient and heirloom varieties of our crop plants to improve our crops so they will be more resilient, high yielding, resource efficient, nutritious, and ready for the future climate of Europe. The knowledge and technology to reach this goal springs from the transformative developments that have occurred in the last 20 years in genomics, phenomics, crop sciences, molecular plant sciences, agronomy, and plant breeding.

Abstract African rice (Oryza glaberrima) has adapted to challenging environments and is a promising source of genetic variation. We analysed dynamics of photosynthesis and morphology in a reference set of 155 O. glaberrima accessions. Plants were grown in an agronomy glasshouse to late tillering stage. Photosynthesis induction from darkness and the decrease in low light was measured by gas exchange and chlorophyll fluorescence along with root and shoot biomass, stomatal density, and leaf area. Steady-state and kinetic responses were modelled. We describe extensive natural variation in O. glaberrima for steady-state, induction, and reduction responses of photosynthesis that has value for gene discovery and crop improvement. Principal component analyses indicated key clusters of plant biomass, kinetics of photosynthesis (CO2 assimilation, A), and photoprotection induction and reduction (measured by non-photochemical quenching, NPQ), consistent with diverse adaptation. Accessions also clustered according to countries with differing water availability, stomatal conductance (gs), A, and NPQ, indicating that dynamic photosynthesis has adaptive value in O. glaberrima. Kinetics of NPQ, A, and gs showed high correlation with biomass and leaf area. We conclude that dynamic photosynthetic traits and NPQ are important within O. glaberrima, and we highlight NPQ kinetics and NPQ under low light.

A range of fungicides including epoxiconazole, azoxystrobin and isopyrazam, were applied to winter wheat at GS 31/32 to determine their effect on photosystem II (PSII) efficiency, biomass and yield. Frequent, repeated measurements of chlorophyll fluorescence were carried on plants grown under different water regimes in controlled environment and in the field to establish the transiency of fluorescence changes in relation to fungicide application. Application of the succinate dehydrogenase inhibitor isopyrazam in a mixture with the triazole epoxiconazole increased PSII efficiency associated with a 28% increase in biomass in the controlled environment and 4% increase in grain yield in the field in the absence of disease pressure. Application of isopyrazam and epoxiconazole increased efficiency of PSII photochemistry (Fv'/Fm') as early as 4h following application associated with improved photosynthetic gas exchange and increased rates of electron transport. We reveal a strong, positive relationship between Fv'/Fm' and CO2 assimilation rate, stomatal conductance and transpiration rate in controlled environment and Fv'/Fm' detected just after anthesis on the flag leaf at GS 73 and grain yield in field. We conclude that application of a specific combination of fungicides with positive effects of plant physiology in the absence of disease pressure results in enhanced biomass and yield in winter wheat. Additionally, an accurate and frequent assessment of photosynthetic efficiency of winter wheat plants can be used to predict yield and biomass in the field.

AbstractPlant scientists and farmers are facing major challenges in providing food and nutritional security for a growing population, while preserving natural resources and biodiversity. Moreover, this should be done while adapting agriculture to climate change and by reducing its carbon footprint. To address these challenges, there is an urgent need to breed crops that are more resilient to suboptimal environments. Huge progress has recently been made in understanding the physiological, genetic and molecular bases of plant nutrition and environmental responses, paving the way towards a more sustainable agriculture. In this review, we present an overview of these progresses and strategies that could be developed to increase plant nutrient use efficiency and tolerance to abiotic stresses. As illustrated by many examples, they already led to promising achievements and crop improvements. Here, we focus on nitrogen and phosphate uptake and use efficiency and on adaptation to drought, salinity and heat stress. These examples first show the necessity of deepening our physiological and molecular understanding of plant environmental responses. In particular, more attention should be paid to investigate stress combinations and stress recovery and acclimation that have been largely neglected to date. It will be necessary to extend these approaches from model plants to crops, to unravel the relevant molecular targets of biotechnological or genetic strategies directly in these species. Similarly, sustained efforts should be done for further exploring the genetic resources available in these species, as well as in wild species adapted to unfavourable environments. Finally, technological developments will be required to breed crops that are more resilient and efficient. This especially relates to the development of multiscale phenotyping under field conditions and a wide range of environments, and use of modelling and big data management to handle the huge amount of information provided by the new molecular, genetic and phenotyping techniques.

Abstract Photocatalytic reduction of CO2 into valuable hydrocarbons using TiO2 is a promising route for mitigating the effects of global warming and meeting future energy demands. However, TiO2 utilises UV light for photocatalysis and its hydrocarbon yields are still low. In order to enhance the light absorption and increase yields, light-harvesting complexes (LHCII) extracted from spinach were attached to the surface of Rh-doped TiO2 (TiO2:Rh) resulting in a hybrid catalyst, TiO2:Rh-LHCII. The LHCII can absorb visible light in green plants, which convert CO2 to sugars via photosynthesis. CO, acetaldehyde and methyl formate were produced from aqueous CO2 solution in a stirred batch reactor under visible-light irradiation. The yields of acetaldehyde and methyl formate were enhanced by almost ten and four times respectively, when using TiO2:Rh-LHCII compared to those of TiO2:Rh.