39,657 research outputs found

    Response of grapevine to irrigation with treated wastewater

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    Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia / Faculdade de Ciências. Universidade do PortoClimate change, population growth, industry expansion and increasing water demand in agriculture are pressuring water resources in dry, warm-climate regions, such as Mediterranean Europe. The aim of this study was to evaluate the possibility of using treated wastewater (TWW) for vineyard irrigation, as a strategy to maintain grapevine's water status within acceptable levels, while contributing to decrease the pressure on natural water resources. To achieve this goal, the effects of TWW and conventional water (CW) on grapevine and soil were compared after two years of irrigation. TWW appears to have had a significant impact on soil salinity, with TWW irrigated soil having a 10% higher salinity (VIC) than the CW irrigated one. Concerning grapevine growth rate and ecophysiology, shoot length of TWW irrigated vines was significantly lower (15%), though there were generally no differences in phenology and reflectance indexes (PRI and NDVI) between treatments. In one measurement during summer peak, though, NDVI values were significantly lower for TWW irrigated vines. Also during summer peak, berries of TWW irrigated vines were significantly darker and greener, and had higher total acidity than CW irrigated vines. Canopy traits such as exposed leaf area, total leaf area and leaf layer number did not differ between treatments, and the same occurred for grape and wood yield, suggesting that TWW had no impact on vine balance and yield. It is crucial to continue exploring the use of TWW for irrigation as an answer to drought and water scarcity, while studying its effects on crops and soil within wider time periods, to scout for long-term impacts of this practiceN/

    A multidimensional genomics approach to unfold the Ethiopian teff (Eragrostis tef) untapped allelic diversity and the genomic architecture of adaptive traits

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    The utilization of locally adapted crop genetic resources is essential to address food insecurity, climate change vulnerability and economic instability in smallholder farming systems. Neglected or Underutilized crop Species (NUS) such as teff (Eragrostis tef), a staple crop in Ethiopia and Eritrea, offer promising opportunities to build resilient agricultural ecosystems and ensure sustainable consumption and production patterns in marginal environments. Advancements in genomics and crop genetic improvement now provide powerful tools to bridge the gap between NUS and 21st century agriculture. This study focuses on the genomic characterization of a core collection of 370 Ethiopian teff accessions held at the Ethiopian Biodiversity Institute (EBI, Addis Abeba, Ethiopia). A bioinformatics workflow was first implemented to map pre-sequenced and demultiplexed Double-Digest Restriction-site Associated DNA Sequencing (ddRAD-Seq) reads on the teff V3 genome and to identify Single Nucleotide Polymorphisms (SNPs). The 31K high quality genome-wide loci identified were implemented in an unsupervised clustering algorithm, a Bayesian inference framework and a neighbor-joining phylogeny to unfold the genetic diversity and the evolutionary history of the teff core collection. Diversity analyses were combined with landscape genomics and environmental-association analysis to uncover spatio-environmental patterns of genetic variation and to identify Quantitative Trait Loci (QTLs) driving local adaptation. Furthermore, genotype information was coupled to previously collected phenotypic and Participatory Variety Selection (PVS) data and integrated in a Mixed Linear Model (MLM)-based Genome Wide Association Study (GWAS) framework to identify polymorphisms associated with adaptive traits. The analyses reveal a subdivision of the population into nine genetic clusters and allow us to infer spatio-environmental genetic patterns across temperature, soil acidity and precipitation seasonality clines. Local adaptation to bioclimatic conditions was contributed by three QTLs, namely S2_2138473, S15_19236753 and S7_382207, which was found to be in linkage disequilibrium with a gene encoding for a LEA-2 domain-containing protein. Significant differences in phenotypic performances and in their relative scores provided by farmers were observed among genetic clusters at the two study sites, corroborating the hypothesis that the broad variation in phenology, plant architecture and, consequently, yield displayed by teff landraces is actively maintained by local adaptation and, interestingly, by farmer cultural patterns. Several significant marker-trait associations (MTAs) and marker-farmer preference associations (MFAs) underpinning phenology, panicle architecture, yield and farmers’ phenotypic performance scores and likely controlling teff adaptive variation, are identified. The multidimensional genomics approach developed in this study, integrating landscape genomics, association mapping and participatory variety selection, paves the way towards integrative germplasm management practices and genomics-assisted breeding efforts

    Remotely Evaluating the Seasonality of Gross Primary Production at High Latitudes

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    A warming trend larger than the global average is changing high-latitude terrestrial ecosystems. The impact of climate change at high latitudes is especially notable on the seasonality of vegetation photosynthesis, such as the Arctic greening, lengthened growing season, and increased peak production in the growing season. As a critical component of the global carbon cycle and land carbon sink, continuously monitoring the seasonal trajectory of ecosystem-level photosynthesis, Gross Primary Production (GPP), is much needed to better understand the climate change impacts and the sensitivity of high-latitude plant communities under global climate change. GPP has been estimated from both ground and space. However, sparsely distributed ground-level measurements are not representative of heterogeneous land cover and complex terrain in high latitudes. Remote sensing techniques provide extensive spatial coverage for comparing GPP at the regional scale. In this thesis, I carefully examine the advances in remote sensing for monitoring GPP at high latitudes, including using hyperspectral reflectance and Solar-Induced chlorophyll Fluorescence (SIF). We show that reflectance near 531 nm can track the seasonality of Light Use Efficiency (LUE), complementing conventional normalized difference vegetation index which is only a proxy of Absorbed Photosynthetic Active Radiation (APAR). Tracking both LUE and APAR is critical for improving GPP estimation, especially in evergreen forests with photosynthetic phenology but sustained canopy color -- a typical land cover type at high latitudes. Satellite-measured SIF can also track both LUE and APAR. Here, it is shown that the empirical model predicting GPP using SIF is land cover dependent. The presence of snow and surface, heterogeneous land cover, and complex terrains in the high latitudes further complicate the interpretation of the SIF-GPP relationship. To improve the accuracy of interpreting SIF in complex terrain, a geometric model is developed to account for variations in APAR on tilted slopes. The results of this thesis enhance the use of both reflectance and SIF to help improve terrestrial biosphere models simulating GPP and cope with model-data uncertainties. The results are also a useful reference for future satellite missions designing instruments and correcting topographic impacts. Overall, this thesis contributes to better evaluating GPP and constraining climate projection uncertainties.</p

    Snow cover phenology is the main driver of foraging habitat selection for a high‚ÄĎalpine passerine during breeding: implications for species persistence in the face of climate change

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    High-alpine ecosystems are strongly seasonal and adverse environments. In these ecosystems, the brevity of optimal breeding conditions means species must efficiently track spatiotemporal variations in resources in order to synchronise their reproductive effort with peaks in food availability. Understanding the details of prey-habitat associations and their seasonality in such ecosystems is thus key for deciphering species’ ecological niches and developing sound conservation action. However, the ecological requirements of high-alpine avifauna remain poorly documented. Furthermore, mountain ranges in the Old World are affected not only by profound alterations of climate, but also by changes in land-use, the interaction of which hampers both proper forecasting of species’ resilience to environmental change and delivery of evidence-based conservation guidance. Here, we investigate the prey-habitat associations of a high-alpine passerine, the White-winged Snowfinch (Montifringilla nivalis), by radio-tracking breeding adults in the Swiss Alps. In late spring and early summer, Snowfinches foraged preferentially next to invertebrate-rich, melting snow patches where Tipulidae larvae abound. Later, in mid-summer, they favoured flower-rich alpine meadows. When foraging, they always preferred short ground vegetation while avoiding rock and scree. Their pattern of foraging habitat selection reflects trade-offs between food abundance and accessibility, i.e. prey availability. The reliance of this passerine on a habitat mosaic where snow plays a major role questions its ability to cope with climate change due to future habitat loss and potential phenological mismatches. Targeted grazing could possibly help in habitat management by aiming at maintaining invertebraterich meadows with short vegetation. Yet, it remains an open question whether habitat management would suffice to compensate for the potentially detrimental effects of the progressive retreat of snow fields to higher elevations

    Dissecting the Heat-Stress Tolerance QTLome in Durum Wheat

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    Heat stress negatively affects wheat performance during its entire cycle, particularly during the reproductive stage. In view of the climate change and the prediction of a continued increase in temperature in the new future, it is urgent to concentrate efforts to discover novel genetic sources able to improve the resilience of wheat to heat stress. In this direction, this study addressed two different experiments in durum wheat to identify novel QTLs suitable to be applied in marker-assisted selection for heat tolerance. Chlorophyll fluorescence (ChlF) is a valuable indicator of plant response to environmental changes allowing a detailed assessment of PSII activity in view of its non-invasive measurement and high-throughput phenotyping. In the first study (Chapter 2), the Light-Induced Fluorescence Transient (LIFT) method was used to access ChlF data to map QTLs for ChlF-related traits during the vegetative growth stage in durum wheat under heat stress condition. Our results provide evidence that LIFT consistently measures ChlF at the level of high-throughput phenotyping combined with high accuracy which is required for Genome-Wide Association Study (GWAS) aimed at identifying genomic regions affecting PSII activity. The 50 QTLs identified for ChlF-related traits under heat stress mostly clustered into five chromosomes hotspots unrelated to phenology, a feature that makes these QTLs a valuable asset for marker-assisted breeding programs across different latitudes. In the second study (Chapter 3), a set of 183 accessions suitable for GWAS, was exposed to optimal and high temperature during two crop seasons under field conditions. Important agronomic traits were evaluated in order to identify valuable QTLs for GY and its components. The GWAS analysis identified several QTLs in the single years as well as in the joint analysis. From the total QTLs identified, 13 QTL clusters can be highlighted to be affecting heat tolerance across different years and/or different traits

    √Čvaluation de l'impact du changement climatique sur la d√©foliation de l'√©pinette noire par la tordeuse des bourgeons de l'√©pinette

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    Les mod√®les √©cologiques actuels pr√©voient de profonds effets des changements climatiques sur les r√©gimes de perturbations naturelles des for√™ts. La tordeuse des bourgeons de l'√©pinette (Choristoneura fumiferana) (TBE) est le principal insecte d√©foliateur dans l'est de l'Am√©rique du Nord. Les √©pid√©mies de TBE ont un impact majeur sur la structure et la fonction de la for√™t bor√©ale canadienne puisque la d√©foliation entra√ģne une diminution de la croissance des arbres, une augmentation de la mortalit√© et une baisse de la productivit√© foresti√®re. Les √©pid√©mies de TBE sont devenues plus s√©v√®res au cours du dernier si√®cle √† cause des changements climatiques; cependant, nous savons peu de choses sur la mani√®re dont l'effet int√©gr√© du climat et du TBE modifie la croissance des esp√®ces h√ītes. Nous √©valuons ici comment l‚Äôinteraction entre le climat et la gravit√© de l'√©pid√©mie affecte la croissance de l'√©pinette noire (Picea mariana) pendant l'√©pid√©mie de TBE qui a eu lieu entre 1968-1988 et 2006-2017. Nous avons compil√© des s√©ries dendrochronologiques (2271 arbres), des donn√©es de s√©v√©rit√© de l'√©pid√©mie (estim√©e par la d√©foliation a√©rienne observ√©e) et des donn√©es climatiques pour 164 sites au Qu√©bec, Canada. Nous avons utilis√© un mod√®le lin√©aire √† effets mixtes pour d√©terminer l'impact des param√®tres climatiques, de la d√©foliation cumulative (des cinq ann√©es pr√©c√©dentes) et de leur effet coupl√© sur la croissance en surface terri√®re. √Ä la gravit√© maximale de l'√©pid√©mie, la croissance en surface terri√®re de l'√©pinette noire a √©t√© r√©duite de 14 √† 18 % sur les cinq ann√©es en raison de l'effet TBE. Cette croissance a √©t√© affect√©e par le climat : des temp√©ratures minimales estivales pr√©c√©dentes plus √©lev√©es et un indice d'humidit√© climatique estival plus √©lev√© ont r√©duit la croissance de 11 % et 4 % respectivement. En revanche, l'effet n√©gatif de la d√©foliation a √©t√© att√©nu√© de 9% pour une temp√©rature minimale plus √©lev√©e au printemps pr√©c√©dent et de 7% pour une temp√©rature maximale plus √©lev√©e l'√©t√© pr√©c√©dent. Cette √©tude am√©liore notre compr√©hension des effets combin√©s de la TBE et du climat et aide √† pr√©voir les dommages futurs caus√©s par cet insecte dans les peuplements forestiers afin de soutenir la gestion durable des for√™ts. Nous recommandons √©galement que les projections des √©cosyst√®mes dans la for√™t bor√©ale incluent plusieurs classes de d√©foliation de la TBE et plusieurs sc√©narios climatiques

    Fruit Crop Improvement with Genome Editing, In Vitro and Transgenic Approaches

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    Fruit species contribute to nutritional and health security by providing micronutrients, antioxidants, and bioactive phytoconstituents, and hence fruit-based products are becoming functional foods presently and for the future. Although conventional breeding methods have yielded improved varieties having fruit quality, aroma, antioxidants, yield, and nutritional traits, the threat of climate change and need for improvement in several other traits such as biotic and abiotic stress tolerance and higher nutritional quality has demanded complementary novel strategies. Biotechnological research in fruit crops has offered immense scope for large-scale multiplication of elite clones, in vitro, mutagenesis, and genetic transformation. Advanced molecular methods, such as genome-wide association studies (GWAS), QTLomics, genomic selection for the development of novel germplasm having functional traits for agronomic and nutritional quality, and enrichment of bioactive constituents through metabolic pathway engineering and development of novel products, are now paving the way for trait-based improvement for developing genetically superior varieties in fruit plant species for enhanced nutritional quality and agronomic performance. In this article, we highlight the applications of in vitro and molecular breeding approaches for use in fruit breeding

    Biological impacts of marine heatwaves

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    Climatic extremes are becoming increasingly common against a background trend of global warming. In the oceans, marine heatwaves (MHWs)‚ÄĒdiscrete periods of anomalously warm water‚ÄĒhave intensified and become more frequent over the past century, impacting the integrity of marine ecosystems globally. We review and synthesize current understanding of MHW impacts at the individual, population, and community levels. We then examine how these impacts affect broader ecosystem services and discuss the current state of research on biological impacts of MHWs. Finally, we explore current and emergent approaches to predicting the occurrence and impacts of future events, along with adaptation and management approaches. With further increases in intensity and frequency projected for coming decades, MHWs are emerging as pervasive stressors to marine ecosystems globally. A deeper mechanistic understanding of their biological impacts is needed to better predict and adapt to increased MHW activity in the Anthropocene
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