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Adapting FLORSYS for climate change: implementing plant-plant competition for water in a 3D mechanistic model for predicting future crop/weed interactions and their consequences in arable cropping systems
No full textInternational audienceIntroductionWeeds compete with crops for light, minerals and water, and weed-related yield losses will probably increase with climate change (drought, heat waves), under the influence of competitive weeds, in particular for increasingly scarcer water resources (Storkey et al., 2021). Thus, cropping systems must be redesigned to make weed management low-input and climate-resilient. FLORSYS is a 3D mechanistic model (Colbach et al., 2021) that can be used to investigate such issues. It simulates the multi-annual dynamics of weeds and their harmfulness (e.g. yield losses) and benefits (e.g. trophic supply for crop auxiliaries) from cropping system (rotation, cultivars, cropping techniques) and pedoclimate. However, FLORSYS does not include all mechanisms relevant to climate change, in particular plant-plant competition for water. To better forecast future weed dynamics in arable cropping systems, this work aimed at developing a water competition submodel for FLORSYS.Material and methodsThe submodel was customised for FLORSYS and connected to other submodels (e.g. growth and phenology, light and nitrogen competition). When possible, it reused existing formalisms. The submodel was designed to be generic across crop and weed species, with few parameters.ResultsAs in Aschehoug et al. (2016), the submodel modelled: (1) water availability, demand, competition and uptake at the voxel (3D pixel) scale, as for light and nitrogen competitions (Munier-Jolain et al., 2013; Moreau et al., 2021) and (2) the consequences of water stress on photosynthesis and morphology at the plant scale (Figure 1).The potential water uptake of a plant in each voxel occupied by its roots is the minimum of (1) its water demand in the voxel, downscaled from total plant demand according to soil water distribution (formalisms from ‘Virtual Grassland’, Louarn and Faverjon (2018)), (2) the amount of water available to plants in the voxel (linked with the STICS soil submodel, Brisson et al. (2008)) and (3) the maximum amount of water roots can take up (experiment of Cournault et al. (2024)). Competition among plants with roots in the voxel only occurs if the available water is insufficient to meet their potential uptakes. After completing the loop across soil voxels, it is possible that some plants did not take up enough water to fulfil their demands in some voxels, while water remains in other occupied voxels. Thus, a second uptake loop is run across voxels to compensate for the initial insufficient uptake.The plant's total water uptake is the sum of water uptakes over all occupied voxels. For each plant, a daily water stress index is computed as “1 - the ratio of water uptake to water demand”. To account for past stresses, the daily indexes are combined into a relative linear combination over the plant life (since emergence), with a greater weight for recent stresses. Together with shading and nitrogen stress indexes, the water stress index can affect photosynthesis (according to DSSAT/APSIM formalisms, Ritchie (1998)), and plant morphology (new formalisms from Cournault et al. (2024), first presentation in this congress).DiscussionFLORSYS becomes the first crop-weed model to account for light, water and nitrogen competitions, with new formalisms accounting for maximum root water uptake and water-stress effects on plant morphology. The new submodel includes only 7 new parameters, in line with FLORSYS’ spirit. It disregards daily lateral soil water flows, but this is consistent with FLORSYS' focus on multiannual cropping system evaluation (Colbach et al., 2021).ConclusionThe new FLORSYS version is expected to improve the credibility of flora projections in the context of climate change. Once the model has been evaluated with field observations, it will be used in simulation studies and participatory workshops with farmers and crop advisors, to design sustainable low-input and climate-resilient cropping systems
Identification of spatial spillovers: Do’s and don'ts
No full textInternational audienceThe notion of spatial spillovers has been widely used in applied spatial econometrics. In this paper, we consider how they can be identified in both structural and causal reduced-form models. First, discussing the various threats to identification in structural models, we point out that the typical estimation framework proposed in the applied spatial econometric literature boils down to considering spatial spillovers as a sideeffect of a data-driven chosen specification. We also discuss the limits of blindly relyingon interaction matrices purely based on geography to identify the source and content of spillovers. Then, we present reduced forms impact evaluation models for spatial data and show that the current spatial versions of usual impact evaluation models are not fully satisfactory when considering the identification issue. Finally, a set of recommendations for applied articles aimed at identifying spatial spillovers is proposed
Impact of environmental storage conditions on properties and stability of a smart bilayer film
No full textInternational audienceThis study aimed to investigate the behavior of smart bilayer films under various temperature and relative humidity (RH). Smart bilayer films were fabricated using sodium alginate with incorporated butterfly pea anthocyanin and agar containing catechin–lysozyme. Cellulose nanospheres were added at concentrations of 0% and 10% w/w of the film and subjected to test at 4 °C and 25 °C, considering different RHs (0%, 50%, and 80%). The results showed that RH had a greater impact on the mechanical properties than temperature, leading to a decrease in tensile strength and an increase in elongation at break with higher RH. The films displayed increased strength but reduced flexibility at low temperatures. Oxygen permeability was negatively affected by increasing RH, while water vapor barrier properties were better at 25 °C than at 4 °C. In terms of color stability, the temperature played a more important role, with both types of smart bilayer films retaining their color stability throughout 14-day storage at 4 °C, even maintaining their ability to change color with pH. However, the films stored at 25 °C exhibited lower color stability and showed potential for color change with varying pH levels, but with lower intensity. The findings of this study demonstrate the significant impact of temperature and RH on the functional properties of smart bilayer films, with and without the addition of cellulose nanospheres. Such smart bilayer films have great potential for various applications, particularly in food packaging, where maintaining color, mechanical, and barrier properties under varying environmental conditions is crucial
Calorie Restriction Decreases Competitive Fitness in Saccharomyces cerevisiae Following Heat Stress
No full textInternational audienceExperiments exposing Saccharomyces cerevisiae to glucose limitation (calorie restriction) are widely used to determine impacts on cell health as a model for aging. Using growth on plates and in liquid culture, we demonstrated that calorie restriction reduces fitness in subsequent nutrient-limited environments. Yeast grown in a calorie-restricted environment took longer to emerge from the lag phase, had an extended doubling time and had a lower percentage of culturability. Cells grown under moderate calorie restriction were able to withstand a gradual heat stress in a similar manner to cells grown without calorie restriction but fared less well with a sudden heat shock. Yeast grown under extreme calorie restriction were less fit when exposed to gradual heating or heat shock. Using RNAseq analysis, we provide novel insight into the mechanisms underlying this response, showing that in the absence of calorie restriction, genes whose products are involved in energy metabolism (glycolysis/gluconeogenesis and the citrate cycle) are predominantly overexpressed when yeasts were exposed to gradual heating, whereas this was not the case when they were exposed to shock. We show that both the culture history and the current environment must be considered when assaying physiological responses, and this has wider implications when developing strategies for the propagation, preservation or destruction of microbial cells
Phenotypic relationships between meat quality parameters and residual feed intake in Japanese black Wagyu cattle
No full textInternational audienceJapanese black Wagyu cattle are renowned for producing some of the world’s most highly valued and recognized beef with exceptional marbling. Therefore, the primary focus of genetic selection for Wagyu cattle has historically been on meat quality, particularly achieving high marbling levels. However, even when the price of the final product is high, production costs also remain high, especially considering that most of the feed has to be imported. The objective of this study was to evaluate phenotypic relationships between feed efficiency, specifically residual feed intake (RFI), as the most utilized efficiency index in cattle, and various meat quality parameters in Japanese black cattle in order to determine if a common phenotypic selection for these parameters could be feasible. For this, a total of 39 Wagyu cattle were evaluated for feed efficiency over their entire fattening period (900 d), with a focus on RFI as a key indicator. Animals were fed high-starch diets with vitamin A deprivation to achieve the desired marbling. Results revealed positive correlations between feed efficiency and meat quality in Wagyu cattle. Specifically, animals with higher feed efficiency exhibited superior meat quality traits, including firmness, marbling, and overall meat rating. When comparing the 20 most extreme RFI individuals (10 most and 10 least efficient), we observed that efficient RFI animals showed increased marbling levels (+13.2%, P = 0.05) and ranking quality (+12%, P = 0.06) of the meat. In conclusion, this research contributes to understanding the interplay between feed efficiency and meat quality in Japanese black Wagyu cattle. Phenotypic correlations observed suggest the possibility of incorporating RFI criteria into genetic selection programs without compromising the prized meat quality traits of Wagyu beef
Ultra-High Irradiance Blue Light Treatment: A Promising Method for Inactivation of the Wine Spoilage Yeast Brettanomyces Bruxellensis
No full textUltra-high irradiance (UHI) blue light treatment is effective in minutes for inactivating not only the planktonic forms but also the sporicidal forms of several microorganisms, including yeasts, filamentous fungi, and bacteria. This treatment could represent a new, cost-effective, and rapid candidate for microbial inactivation in a wide range of applications, such as food or surface treatment. Our study characterized the effects of UHI blue light treatments on Brettanomyces bruxellensis planktonic or biofilm forms that can be formed on the most representative surfaces of the wine industry (wood and stainless steel). B. bruxellensis is the main spoilage microorganism of red wines and constitutes a growing problem for winemakers. Treatments of 1 to 5 min (22.2 J.cm–² to 111 J.cm–²) were performed on planktonic cells and 1 to 10 min (22.2 J.cm–² to 222 J.cm–²) on biofilms. Cultivability on yeast peptone dextrose agar medium and viability (esterase activity) of the yeasts were analyzed after treatment for each of the treatment modalities using flow cytometry after labeling with 5-carboxyfluorescein diacetate, acetoxymethyl ester. The findings of this study showed the possibility of inactivating both the planktonic forms of B. bruxellensis in phosphate-buffered saline or wine and the forms of biofilm developed on wood or stainless steel in wine or yeast peptone dextrose using UHI blue light treatments. Treatments lasting less than 10 min resulted in a loss of cultivability but a lesser loss of viability. However, a 10-min treatment resulted in a complete loss of viability for all types of biofilms studied. Therefore, this treatment process appears particularly promising for eliminating biofilms that can develop on surfaces in contact with food products, as is the case for Brettanomyces on surfaces representative of the wine industry
Identification of volatile and odor‐active compounds in pea protein fractions obtained by a modified extraction method using fermentation
No full textInternational audienceThis study investigates the aromatic composition of pea albumin and globulin fractions obtained through either fermentation or conventional acidification using hydrochloric acid (control) toward the isoelectric point of pea globulins. Different lactic acid bacteria were used including S. thermophilus (ST), L. plantarum (LP), and their coculture (STLP). The volatile compounds were extracted by solvent‐assisted flavor evaporation technique and quantified by gas chromatography–mass spectrometry (GC‐MS). Odor‐active compounds (OAC) were further characterized by gas chromatography–olfactometry (GC‐O). In total, 96 volatile and 36 OACs were identified by GC‐MS and GC‐O, respectively. The results indicated that the protein fractions obtained by conventional acidification were mainly described by green notes for the presence of different volatile compounds such as hexanal. However, the samples obtained by fermentation had a lower content of these volatile compounds. Moreover, protein fractions obtained by coculture fermentation were described by volatile compounds associated with fruity, floral, and lactic notes. Practical Application The insights from this study on pea protein aroma could find practical use in the food industry to enhance the sensory qualities of plant‐based products. By utilizing fermentation methods and specific lactic acid bacteria combinations, manufacturers may produce pea protein with reduced undesirable green notes, offering consumers food options with improved flavors. This research may contribute to the development of plant‐based foods that not only provide nutritional benefits but also meet consumer preferences for a more appealing taste profile
Intentions d’usage et fonctions de l’image vidéo pour former : Transformer et comprendre une situation industrielle
No full textInternational audienceVideo images are now ubiquitous as a medium for training and professional development. Most of the images captured and used are in fact in the name of reference frameworks or didactic situations attached to a programme. This article looks at the functions that these video images can play in a vocational training process that does not know its purpose. This is the case in technical universes where new problems arise: the aim is then to use video images to teach a dual dynamic of transforming and understanding. Transforming the work actions put to the test here by the necessary modifications to the process, under the constraint of a similar production process. To gain a deep understanding of the phenomena involved in transformation, so as to be able to reproduce them in action, but also to share them by naming them and explaining them. The order transform/understand is subverted on the one hand by the previous experience of those involved in production and on the other by watching videos that suspend action to give time for reflection. Because they form a trace and offer the possibility of looking back on the action, the use of video images plays a number of structuring roles in a training course, in the heritage of know-how and in the production/transmission processes. These functions result from the articulation of images as data with other ethnographic, documentary or immersive survey data. They are constructed by the complementary status of this articulation, which is in turn i) comprehensive (through the identification and construction of the production problem); ii) transitional from understanding to transforming (through a naming operation that distinguishes the description of a process, its conceptual charge, from its registration and use in the work flow); iii) deliberative of the relevance of this transforming dynamic on the common culture of the trade between the different stakeholders.Les images vidéo sont aujourd’hui omniprésentes comme supports de la formation ou de la professionnalisation. Une majorité des images captées et exploitées le sont en effet au nom de référentiels, de situations didactiques attachées à un programme. Cet article s’intéresse aux fonctions que ces images vidéo peuvent jouer dans un processus de formation professionnelle qui ne connaît pas son objet. C’est le cas dans des univers techniques où des problèmes inédits surgissent : il s’agit alors d’instruire avec l’aide des images vidéo une double dynamique transformer/comprendre. Transformer les actions du travail mises à l’épreuve ici par de nécessaires modifications du procédé, sous contrainte d’un process de production similaire. Comprendre profondément les phénomènes en jeu dans la transformation pour être en capacité de les reproduire en action, mais également de les partager en les nommant et en les explicitant. L’ordre transformer/comprendre est subverti d’une part, par l’expérience antérieure des acteurs de la production et d’autre part, par un visionnage de vidéos qui suspend l’action pour donner du temps à la réflexion. Parce qu’elles font trace et qu’elles offrent la possibilité de retours sur l’action, le recours aux images vidéo joue plusieurs fonctions structurantes d’un parcours de formation, de patrimonialisation de savoir-faire et de processus productifs/transmissifs. Ces fonctions résultent de l’articulation des images comme données avec d’autres données d’enquêtes ethnographique, documentaire ou immersives. Elles se construisent par le statut complémentaire de cette articulation tour à tour i) compréhensive (par l’identification et la construction du problème productif) ; ii) transitionnelle du comprendre au transformer (par une opération de nommage qui amène à distinguer la description d’un procédé, sa charge conceptuelle, à son inscription et son usage dans le flux du travail) ; iii) délibérative de la pertinence de cette dynamique transformante sur la culture commune de métier entre les différentes parties prenantes
Former à la gestion des haies multifonctionnelles : accompagnement d’équipes pédagogiques engagées dans des dispositifs partenariaux territoriaux et scientifiques
No full textInternational audienceFace aux changements climatiques et avec la transition agroécologique, la haie retrouve une réelle pertinence dans les systèmes agricoles, y compris ceux des établissements d’enseignement et de formation agricoles. Cette orientation « de transition » se traduit par des activités de sensibilisation aux rôles des haies et des plantations nouvelles. La gestion de l’existant, une réelle intégration de la haie aux agroécosystèmes et les démarches nécessaires d’accompagnement de ce mouvement restent cependant plus rares
Ancient varieties can help control weed density while preserving weed diversity
No full textInternational audienceWeeds are a major component of agricultural diversity affecting crop yield and ecosystem services. Compared to modern wheat (Triticum aestivum) varieties, ancient wheat cultivars (released before 1960) are taller, and this trait can be used to control weeds in organic farming systems. However, there is still a lack of quantitative assessments of the relative contribution of wheat breeding-history (ancient vs modern varieties) and synthetic inputs in explaining weed density and community structure. In this study, a field experiment was undertaken where five modern and five ancient wheat varieties were either treated as in a conventional system with synthetic inputs (nitrogen, herbicide and fungicide) or as in an organic system without the use of synthetic inputs. Crop light interception and weed density were recorded for 12 weeks until crop maturity. On average, ancient varieties reduced weed density by 17% compared with modern varieties, while the application of chemical inputs was responsible for an average reduction of 37%. The stronger competitive effect of ancient varieties was associated with increased sunlight interception. Species richness was higher in the absence of inputs for some weeks, but not by the end of the experiment. The field-based results illustrated that ancient varieties can be used to help control weed density in organic systems that do not rely on synthetic inputs for weed control Despite this effect of crop interference on weed density, a reduction in weed diversity was not observed. These findings could be of particular interest to promote agrobiodiversity in agricultural systems without synthetic inputs