Periodic Reporting for period 4 - SolACE (Solutions for improving Agroecosystem and Crop Efficiency for water and nutrient use) Reporting period: 2021-05-01 to 2022-09-30 Summary of the context and overall objectives of the project SolACE overarching goal has been to help European agriculture dealing with more frequent combined limitations of water and nutrients (N and P) in the coming decades, through the design of novel crop genotypes and agroecosystem management innovations to improve water, N and P use efficiency, with a focus on 3 major crops - potato, bread and durum wheat. SolACE aimed to identify the (i) optimum combinations of above- and below-ground traits for improving resource use efficiency, (ii) best-performing genotypes under combined water and N/P stress and (iii) novel practices that make better use of plant-plant and plant-microbe interactions to access such resources in conventional, organic and conservation agriculture. A double interactive innovation loop has been implemented, based on agroecosystem management and breeding strategies, and implying the engagement of end-users across the production chain. The tested innovations included crop genotype mixtures, legume-based crop rotations, consortia of microbial inoculants, improved decision support systems and hybrids or products from genomic selection and participatory evolutionary breeding schemes. Complementary approaches have been used, from data mining, modelling, phenotyping in high throughput platforms and field conditions, to experiments in research stations and farmer networks in contrasted pedoclimatic zones. Through co-designing and co-assessing with end-users the tested breeding and management innovations to increase resource use efficiency, SolACE outputs have been and will be available for dissemination to a broad range of stakeholders, including policy-makers. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far The data collected with harmonised formats have been shared in SolACE repository and used to parameterise crop models to evaluate wheat and potato production in Europe based on present and projected climate for various management scenarios. Experiments have been conducted with diverse germplasms for each crop to identify key root/microbiome traits and aboveground traits (or combinations of) contributing to crop tolerance to combined water and N/P limitations. Roots and shoots were phenotyped in controlled and field environments in large diversity panels for each crop. Smaller scale field trials for finer analyses of crop responses to combined stress and simulation with coupled crop / root architecture models have also been part of the strategy. Novel breeding strategies and tools have been designed to identify gene-derived markers for above- and belowground traits of crop adaptation to combined stress. Genomic selection (GS) models based on root traits were produced and tested in wheat. A participatory breeding strategy was applied in farmer communities in organically-grown durum wheat, and changes driven by combined stresses was studied in evolutionary breeding population. New F1 hybrids in diploid potato and bread wheat have been produced and tested for adaptation to combined stresses. A range of management practises have also been tested in controlled prior to field conditions: microbial strain combinations, crop rotations and durum wheat genotype mixtures. Numerous field trials have been performed across Europe to test these different management practices designed to improve stress resilience. Seven farmers’ networks have been set-up to test combinations of some of the above-mentioned novel genotypes and management practices on-farm with contrasting pedoclimatic conditions throughout Europe. Life Cycle Analysis (LCA) has been used to conduct a multicriteria assessment of the innovations tested within these networks. Stakeholder workshops were held to collect feedbacks on tested innovations.Crop modelling showed a wide diversity of crop responses to climate change, either negative in Southern and Eastern regions of Europe, or rather positive in other areas: there, yield improvement due to increased CO2 and temperature may indeed occur, assuming no other stress would occur. Experiments and model simulations with diverse wheat and potato germplasms showed under which circumstances crop/root/microbiome traits (or combinations of) contributed to crop tolerance to combined water and N/P stress. Significant diversity and plasticity of root traits was found, making SolACE efforts a first step forward, in spite of the difficulties to isolate traits supporting crop performance. Deep rooting emerged as an essential trait for drought adaptation and nutrient acquisition at depth. Root-trait based GS models were set up and validated for improving wheat yield adaptation under multiple stresses. Experimental F1-hybrid produced in potato and bread wheat proved quite efficient to face multiple stresses in field conditions. In durum wheat, participatory breeding strategy led to new populations evolved from a genetically diverse population, involving organic farmers in Hungary and Italy. In addition to these breeding strategies and products, the tested management innovations proved more or less efficient under combined drought and N/P limitations. While using legumes as precrop or reduced tillage revealed often efficient, durum wheat genotype mixtures and formulated microbial consortia inoculants proved promising, although their effect under field conditions was not always significant. Engagement of farmers with the project has raised interest and enthusiasm for most of the tested innovations. On-farm experiments highlighted the potential of grain legumes in rotations to reduce the C footprint of cereals and improve the economic margin to farmers, based on LCA. On-farm experiments showed inconsistent results for microbial inoculants and experimental potato hybrids, but farmers were keen to further assess such innovations over a larger number of trialling years. SolACE partners engaged stakeholders beyond farmers through a series of events and modes of interaction. Practice abstracts, videos, training materials, specialized press and newsletters, and policy briefs have been made available on the SolACE website and community on Zenodo. Further exploitation of some of the findings is currently being considered for the work conducted on microbial inoculants, F1-hybrids of bread wheat and potato, as well as for durum wheat populations derived from the participatory approach. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) SolACE advanced our knowledge on how combined water and N/P limitations impact yield and quality of conventionally- or organically-grown potato, bread and durum wheat, and solutions to better cope. Including root traits identified by phenotyping large diversity panels in GS and new ideotypes for breeding schemes were novel solutions. Potato and bread wheat F1-hybrids proved promising to stack traits associated with distinct stress tolerance (including root). Participatory breeding in durum wheat populations with large trait diversity proved efficient to raise farmers’ interest. On top of such solutions, a range of management innovations have been tested, targeting techniques making use of belowground interactions and biodiversity to use soil resources more efficiently: consortia of microbial inoculants, mixtures of genotypes or rotational legumes. Combinations of these novel genotypes and management practices need to be co-designed and co-assessed on-farm with relevant stakeholders across Europe, as achieved in SolACE, for their effective uptake at the right scale to ultimately achieve an ecological intensification of European agriculture in the context of climate change. solace-logo-title-rgb.jpg
