Pulses are an important component in crop rotations in the semiarid Brown soil zone of southern Saskatchewan, Canada. Besides their capability to fix nitrogen, pulse crops establish a strong symbiotic relationship with arbuscular mycorrhizal fungi (AMF), which have been shown to increase nutrient and water uptake through hyphal extensions in the soil. Incorporating strongly mycorrhizal crops in a rotation may increase inoculum levels in the soil and benefit the growth of a subsequent crop. The objective of this study was to determine if AMF potential and colonization of a durum crop is significantly affected by cropping history and to assess the impact of pulses in crop rotations on the abundance and diversity of AMF communities in the soil. In 2004 and 2005, soil, plant, and root samples were taken on Triticum turgidum L. (durum) with preceding crops of Pisum sativum L. (pea), Lens culinaris Medik (lentil), Cicer arietinum L. (chickpea), Brassica napus L. (canola) or Triticum turgidum L. (durum). Although there were few differences in soil N and P levels, previous crop had a significant effect (p<0.05) on durum yields in both years. A previous crop of pea was associated with the highest yields, while the durum monocultures were lowest. Arbuscular mycorrhizal potential and colonization were significantly affected (p<0.05) by cropping history, but not consistently as a result of inclusion of a pulse crop. Phospholipid and neutralipid fatty acids (PLFA/NLFA) were completed to analyse the relative abundance of AMF (C16:1ù5), saprophytic fungi (C18:2ù6), and bacteria in the soil. The effect of treatment on the abundance of AMF, saprotrophic fungi and bacteria were not significant (p<0.05), but the changes over time were. These results demonstrate that although previous crop may play a role in microbial community structure, it is not the only influencing factor.

Pulses are an important component in crop rotations in the semiarid Brown soil zone of southern Saskatchewan, Canada. Besides their capability to fix nitrogen, pulse crops establish a strong symbiotic relationship with arbuscular mycorrhizal fungi (AMF), which have been shown to increase nutrient and water uptake through hyphal extensions in the soil. Incorporating strongly mycorrhizal crops in a rotation may increase inoculum levels in the soil and benefit the growth of a subsequent crop. The objective of this study was to determine if AMF potential and colonization of a durum crop is significantly affected by cropping history and to assess the impact of pulses in crop rotations on the abundance and diversity of AMF communities in the soil. In 2004 and 2005, soil, plant, and root samples were taken on Triticum turgidum L. (durum) with preceding crops of Pisum sativum L. (pea), Lens culinaris Medik (lentil), Cicer arietinum L. (chickpea), Brassica napus L. (canola) or Triticum turgidum L. (durum). Although there were few differences in soil N and P levels, previous crop had a significant effect (p<0.05) on durum yields in both years. A previous crop of pea was associated with the highest yields, while the durum monocultures were lowest. Arbuscular mycorrhizal potential and colonization were significantly affected (p<0.05) by cropping history, but not consistently as a result of inclusion of a pulse crop. Phospholipid and neutralipid fatty acids (PLFA/NLFA) were completed to analyse the relative abundance of AMF (C16:1ù5), saprophytic fungi (C18:2ù6), and bacteria in the soil. The effect of treatment on the abundance of AMF, saprotrophic fungi and bacteria were not significant (p<0.05), but the changes over time were. These results demonstrate that although previous crop may play a role in microbial community structure, it is not the only influencing factor.

My dissertation research investigates the genetic architecture and evolutionary significance of physiological variation in two wildflower species, Ipomopsis aggregata and Arabidopsis thaliana. In particular, my work focuses on water use efficiency (WUE), a critical physiological trait that dictates plant growth and performance in resource-limited environments. I used a combination of quantitative trait loci (QTL) mapping, field selection experiments, and classic quantitative genetics to investigate 1) the genetic architecture of water use efficiency and flowering time, 2) patterns of natural selection on water use efficiency, flowering time, and other ecological traits in I. aggregata, and 3) additive genetic variation, genetic correlations, and selection on water use efficiency, flowering time, and plasticity to drought in Arabidopsis thaliana. Using an Ipomopsis aggregata genetic mapping population, I identified four QTL underlying WUE, three QTL-QTL epistatic interactions, and evidence for a possible QTL x cytoplasmic interaction affecting WUE. I found a similar genetic architecture underlying flowering time, with four main effect QTLs that all adjacently localized to the same linkage groups as WUE, and three QTL-QTL epistatic interactions, which occur between the same chromosome pairs as the WUE interactions. The combined main and interactive effects explain 35% and 40% of the phenotypic variation in WUE and flowering time, respectively. The adjacent localization suggests a possible role for the evolution of co-inheritance or, if the true QTL positions actually overlap, a possible role for pleiotropy underlying the phenotypic correlation between WUE and flowering time. Additionally, these results suggest epistasis is a significant factor affecting phenotypic variation in nature. In a reciprocal transplant and water addition experiment, I demonstrated variable natural selection on WUE, flowering time, and nectar production in I. aggregata across elevation/habitat and differential water availability. At low elevation in the water addition treatment, natural selection favors early flowering and greater nectar sugar concentration, while dry conditions favor high WUE and early flowering time. At high elevation, where the growing season is shorter and drier, selection favors early flowering regardless of water addition. These results suggest natural selection on ecophysiological and floral traits varies with resource availability (e.g. water availability and pollinator visitation). Using data from a glasshouse experiment involving a global panel of accessions of Arabidopsis thaliana, I demonstrated strong positive genetic correlation between WUE and flowering time, as well as selection for low WUE and early flowering under experimental season-ending drought. Finally, I found significant genetic variation in plasticity as well as selection favoring greater WUE plasticity under drought, indicating plasticity to drought is adaptive in A. thaliana. / text

Grünlandfutter mit einem hohen Ertrag und gutem Futterwert ist eine Grundvoraussetzung für die effiziente Produktion von wiederkäuenden Nutztieren. Im Zuge des prognostizierten Klimawandels werden sich die Niederschlagsmuster ändern und das Auftreten von Extremwetterereignissen, wie temporärer Trockenheit, wird sich erhöhen. Besonders produktives Grünland benötigt aber eine ausreichende und regelmäßige Wasserversorgung während der Wachstumsperiode. Deshalb werden die Futterproduktion von Grünland, die Ertragsstabilität und der Futterwert von temporärer Trockenheit beeinflusst werden. Aus diesem Grund sind Anpassungsstrategien nötig, um eine zukünftige und nachhaltige Grünlandfuttererzeugung zu sichern. Erhöhte pflanzliche Biodiversität wird oft als Möglichkeit angesehen, Funktionen von Ökosystemen, wie Produktivität und Futterwert, im Grünland zu verbessern. Es gibt eine fortlaufende Diskussion wie eine erhöhte Artenzahl auf Stress, besonders Trockenstress, reagiert und wie dabei Produktivität, Futterwert und Wassernutzung beeinflusst werden. Andere Untersuchungen zeigten, dass Artidentität und die Zusammensetzung der funktionellen Gruppen wichtige Faktoren für Produktivität und Futterwert sind. Auf Grund dessen haben wir von Juli 2009 bis Juni 2011 ein Trockenstressexperiment in einer Vegetationshalle durchgeführt. Verschiedene temporäre Trockenstressereignisse wurden in drei Aufwüchsen in zwei Vegetationsperioden durchgeführt. Die klimatischen Verhältnisse in der Vegetationshalle folgten normalen saisonalen Verläufen mit Frost im Winter und höheren Temperaturen im Sommer. Trockenstress wurde induziert, indem, nach einer anfänglichen Bewässerung, die Wasserversorgung für einen bestimmten Zeitraum eingestellt wurde. Die Wasserverfügbarkeit des Bodens konnte dabei immer kontrolliert werden. Für das Experiment wählten wir ertragsstarke und landwirtschaftlich nutzbare Arten des Grünlands der gemäßigten Zonen aus. Die Arten wurden in Monokultur und Drei- sowie Fünfartenmischungen gesät und enthielten die funktionellen Gruppen Leguminose (Trifolium repens L.), Gras (Lolium perenne L., Dactylis glomerata L.) und Kraut (Plantago lanceolata L., Taraxacum officinale F.H. Wigg. agg.). Der von uns gewählt Umfang der Artenzahl zeigte schon in anderen Biodiversitätsexperimenten einen Einfluss auf die Produktion. Untersucht wurden die Effekte von Artenzahl und funktionellen Gruppen auf Ertrag, Ertragsstabilität, Wassernutzung und Futterwert (Rohprotein, wasserlösliche Kohlenhydrate, neutrale und saure Detergenzienfasern). Als Indikatoren für die Ertragsentwicklung und die agronomische Wassernutzungseffizienz (Verhältnis von Ertrag zu Wasserverbrauch) dienten der Stickstoffertrag und die Stickstoffkonzentration der Bestände sowie δ13C Signaturen, sowohl mit unlimitierter Wasserversorgung als auch mit Trockenstress. Überdies führten wir 2009 ein Kurzzeitfeldexperiment auf einem alten Grünlandbestand auf dem Versuchsgut der Universität Göttingen in Reliehausen durch. In diesem Versuch wurde ebenso der Einfluss von Trockenstress und Artenzahl auf den Ertrag und die Wassernutzung untersucht. Unsere Daten zeigten, dass Trockenstress die Produktivität verringert und die Wassernutzung beeinflusst, beides abhängig von der Stärke des Stresses. Bei moderatem Stress war die agronomische Wassernutzungseffizienz unverändert oder stieg leicht an, bei starkem Stress verringerte sie sich jedoch. Der Stickstoffertrag und die Stickstoffkonzentration waren brauchbare Indikatoren für die agronomische Wassernutzungseffizienz, wohingegen δ13C weniger geeignet war. Die agronomische Wassernutzungseffizienz wurde von Stickstoff erhöht. Es gab keinen oder nur einen sehr geringen Einfluss von Trockenstress auf den Futterwert. Saisonale Effekte hatten mehr Einfluss auf den Futterwert. Allgemein scheint der Ertragsrückgang wichtiger als die Veränderungen des Futterwerts zu sein. Die Artenzahl beeinflusste den Futterwert und die Ertragsstabilität über die Vegetationsperiode nicht. Mit Hilfe des “sampling effect“ (Probennahmeeffekt) können der manchmal positive Einfluss der Artenzahl auf den Ertrag und die agronomische Wassernutzungseffizienz und der Rückgang dieses Einflusses unter Trockenheit erklärt werden. Mit erhöhter Artenzahl stieg der Anteil der leistungsfähigen, aber trockenheitssensitiven Leguminose. Weiterhin gab es einen Hinweis, dass die Artenzahl die Geschwindigkeit des Wasserverbrauchs erhöht. Die Ergebnisse des Feldexperiments bekräftigten die Befunde bezüglich der Effekte des Trockenstresses, des Ertrages und der Wassernutzung. Aus diesen Gründen kann die „insurance hypothesis“ (Versicherungshypothese), die besagt, dass eine erhöhte Artenzahl Ökosystemfunktionen gegenüber Umweltveränderungen stabilisieren kann, nicht bestätigt werden. Jedoch waren die funktionellen Gruppen wichtige und bestimmende Faktoren der Leistung unter nicht Wasser limitierten Bedingungen und Trockenstress. Die Leguminose hatte besonders auf Ertrag, agronomische Wassernutzungseffizienz und Rohprotein einen positiven Einfluss, jedoch erhöhte sie auch den Wasserverbrauch und die saisonale Variabilität. Gräser stabilisierten den Ertrag und den Wasserverbrauch und erhöhten die wasserlöslichen Kohlenhydrate sowie die Faserfraktionen, während sie den Ertrag und die agronomische Wassernutzungseffizienz unter den stickstofflimitierten Bedingungen unseres Experiments verringerten. Die funktionelle Gruppe Kräuter zeigte ähnliche Ergebnisse bezüglich Ertrag und Wassernutzung, aber sie erhöhte das Rohprotein. Unsere Ergebnisse demonstrieren, dass die vorhergesagte Zunahme von Trockenstressereignissen die Produktion reduzieren und die Wassernutzung ändern wird. Änderungen im Futterwert werden dabei weniger wichtig als der Ertragsrückgang sein. Für die Produktion, die Wassernutzung und den Futterwert wird die Artenanzahl weniger relevant sein als die funktionelle Zusammensetzung von Grünland. Deshalb wird eine angepasste Grasnarbenzusammensetzung für die Sicherung der Produktion von wiederkäuenden Nutztieren unter den Bedingungen des erwarteten Klimawandels Bedeutung erlangen.

Wastewater treatment is traditionally considered a separate part of an industrial activity, hardly connected to the production units themselves. It is nowadays essential to ensure that the quality of water is not degraded and that water that has been polluted is purified to acceptable levels, especially in a country with scarce water resources such as South Africa. Where water quality is concerned, Zero Effluent Discharge (ZED) is the ultimate goal, in order to avoid any releases of contaminants to the water environment. The push towards ZED in South Africa is also promoted further by the South African Government’s plan to reduce freshwater usage and the pollution of water sources due to the water scarcity in a semi-arid South Africa. Future legislation will see a marked increase in the cost of freshwater usage and/or a possible limitation of the quantity of freshwater available. There is a need in the South African Industry for a framework of Best Management Practices (BMPs) in order to provide interested stakeholders, which include not only industry, but also academia, environmental interest groups and members of the public, with a procedure to meet the ZED statutory requirements. This dissertation explores the regulatory requirements and current environmental management practices implemented. A framework of BMPs to successfully attain ZED status in South African industries is developed from the literature study and the researcher’s own experience. The BMP framework embodies practices for one integrated strategy within three dimensions. The three dimensions of the BMP framework were selected to differentiate between BMPs for management (Governance BMPs), the project management team responsible for ZED projects (Project Management BMPs) and the implementation of preventative and operational measures to obtain and sustain ZED compliance for South African industries. The BMP framework was validated against the practices applied by Mittal Steel. The Mittal Steel plant in Vanderbijlpark implemented various projects, reduced the intake of water and eliminated the discharge of effluent and by doing this successfully realised their ZED status. The BMP framework will enable South African industries to develop their own BMPs Manual which should be specific to their operational and environmental requirements. The implementation of these BMPs should be tailored and used accordingly to demonstrate compliance to ZED requirements in South African industries. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2009.

Wastewater treatment is traditionally considered a separate part of an industrial activity, hardly connected to the production units themselves. It is nowadays essential to ensure that the quality of water is not degraded and that water that has been polluted is purified to acceptable levels, especially in a country with scarce water resources such as South Africa. Where water quality is concerned, Zero Effluent Discharge (ZED) is the ultimate goal, in order to avoid any releases of contaminants to the water environment. The push towards ZED in South Africa is also promoted further by the South African Government’s plan to reduce freshwater usage and the pollution of water sources due to the water scarcity in a semi-arid South Africa. Future legislation will see a marked increase in the cost of freshwater usage and/or a possible limitation of the quantity of freshwater available. There is a need in the South African Industry for a framework of Best Management Practices (BMPs) in order to provide interested stakeholders, which include not only industry, but also academia, environmental interest groups and members of the public, with a procedure to meet the ZED statutory requirements. This dissertation explores the regulatory requirements and current environmental management practices implemented. A framework of BMPs to successfully attain ZED status in South African industries is developed from the literature study and the researcher’s own experience. The BMP framework embodies practices for one integrated strategy within three dimensions. The three dimensions of the BMP framework were selected to differentiate between BMPs for management (Governance BMPs), the project management team responsible for ZED projects (Project Management BMPs) and the implementation of preventative and operational measures to obtain and sustain ZED compliance for South African industries. The BMP framework was validated against the practices applied by Mittal Steel. The Mittal Steel plant in Vanderbijlpark implemented various projects, reduced the intake of water and eliminated the discharge of effluent and by doing this successfully realised their ZED status. The BMP framework will enable South African industries to develop their own BMPs Manual which should be specific to their operational and environmental requirements. The implementation of these BMPs should be tailored and used accordingly to demonstrate compliance to ZED requirements in South African industries. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2009.

Submitted by Ronildo Prado (ronisp@ufscar.br) on 2017-08-16T20:20:29Z No. of bitstreams: 1 DissTGM.pdf: 2889804 bytes, checksum: c55eea68163f4e92468140f7d3ced089 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-16T20:20:36Z (GMT) No. of bitstreams: 1 DissTGM.pdf: 2889804 bytes, checksum: c55eea68163f4e92468140f7d3ced089 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-16T20:20:43Z (GMT) No. of bitstreams: 1 DissTGM.pdf: 2889804 bytes, checksum: c55eea68163f4e92468140f7d3ced089 (MD5) / Made available in DSpace on 2017-08-16T20:20:49Z (GMT). No. of bitstreams: 1 DissTGM.pdf: 2889804 bytes, checksum: c55eea68163f4e92468140f7d3ced089 (MD5) Previous issue date: 2017-04-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The tomato is a demanding crop in regards to water and is among the most consumed vegetables in Brazil. The search for alternatives to improve tomato productivity, as well as reduce the water use in the crop cycle, is essential for agricultural production and environment. The objectives of this work were to evaluate the contribution of subsurface drip irrigation to yield and fruit quality of Grape tomatoes and to estimate the water use efficiency (EUA). The experiment was carried out in the CCA / UFSCar and consisted of three treatments with four randomized blocks. Irrigation management considered the storage soil water capacity (CAD), the soil moisture being high according to the water content reference of the treatment, 0.33 (T1), 0.29 (T2) and 0.25 m3 m-3 (T3), corresponding to 100 % replacement of CAD, and deficit irrigations of 75 and 50 % of CAD, respectively. Water content was monitored by TDR probes and the roots depth obtained through a root images scanner. The Grape tomatoes were transplanted under drip lines installed at 0.20 m depth. Quantitative and qualitative characteristics of the fruits were evaluated in relation to the proposed treatments, being: fruits number per plant, average fruit mass and productivity, quantitative characteristics and; Diameter, length, soluble solids, fruit pH and dry mass of leaves and stem, qualitative characteristics. The total water applied was 1297 mm in T1, 471 mm in T2 (36 % of water applied in T1) and 234 mm in T3 (18 % of T1). Among the characteristics evaluated, the T2 did not differ from the T1 treatment, except in the diameter and pH. The T3 treatment was equal to T1 only in the fruits number per plant. The average fruit mass was different among all treatments and there was no difference between soluble solids values. The T3 treatment obtained higher EUA, followed by T2 and T1, but did not have higher productivity nor better results in other evaluated attributes. Deficit subsurface irrigation of 75 % of CAD did not interfere in Grape tomato productivity and fruit quality, being the most recommended because of qualitative and quantitative attributes similar to full irrigation and to increase the EUA. It is concluded that deficit subsurface irrigation had productivity and fruit quality of Grape tomatoes like full irrigation when used 75 % of CAD, increased the water use efficiency and contributed with water use reduction in crop cycle. / O tomateiro é uma cultura exigente em água e está entre as hortaliças mais consumidas no Brasil. A busca por alternativas que melhorem sua produtividade, bem como reduzam o uso da água no ciclo da cultura, é essencial para a produção agrícola e para o meio ambiente. Este trabalho teve o objetivo avaliar a contribuição da irrigação subsuperficial deficitária na produtividade e qualidade dos frutos de tomateiros Grape e estimar a eficiência no uso da água (EUA). O experimento foi realizado no CCA/UFSCar e consistiu de três tratamentos com doze parcelas em blocos casualizados. O manejo da irrigação levou em consideração a capacidade de água disponível no solo (CAD), sendo a umidade do solo elevada de acordo com a umidade de referência do tratamento, 0,33 (T1), 0,29 (T2) e 0,25 m3 m-3 (T3), correspondendo à reposição de 100 % da CAD, e irrigações deficitárias de 75 e 50 % da CAD, respectivamente. A umidade do solo foi monitorada por sondas TDR e o crescimento das raízes por imagens obtidas através de scanner de raízes. As mudas de tomateiro Grape foram transplantadas sob linhas de gotejamento instaladas a 0,20 m de profundidade. Foram avaliados atributos quantitativos e qualitativos dos frutos em relação aos tratamentos propostos, sendo eles: número de frutos por planta, massa média dos frutos e produtividade como atributos quantitativos; diâmetro, comprimento, sólidos solúveis, pH dos frutos e massa seca das folhas e caule como atributos qualitativos. A lâmina total de água aplicada foi 1297 mm em T1, 471 mm em T2 (36 % da lâmina aplicada em T1) e 234 mm em T3 (18 % de T1). Entre os atributos avaliados, o diâmetro e pH dos frutos do tratamento T2 diferiram do T1. Já o tratamento T3 foi igual ao T1 apenas no número de frutos por planta. A massa média dos frutos foi diferente entre todos os tratamentos e não houve diferença no valor de sólidos solúveis. O tratamento T3 obteve maior EUA, seguido por T2 e T1, porém não teve maior produtividade e nem melhores resultados em outros atributos avaliados. A irrigação subsuperficial deficitária de 75 % da CAD não interferiu na produtividade do tomateiro Grape e na qualidade dos frutos, sendo a mais recomendada por apresentar atributos qualitativos e quantitativos similares à irrigação plena e aumentar a EUA. Conclui-se com este trabalho que irrigação subsuperficial deficitária teve produtividade e qualidade de frutos de tomateiro Grape semelhante à irrigação plena quando utilizado 75 % da CAD, aumentou a eficiência no uso da água e contribuiu com a redução no uso da água no ciclo da cultura.

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-02-14T19:11:01Z No. of bitstreams: 1 JonasOF_TESE.pdf: 3319263 bytes, checksum: 51b79bea8bd5a5a042d4db215bfe1a86 (MD5) / Approved for entry into archive by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-02-15T14:50:14Z (GMT) No. of bitstreams: 1 JonasOF_TESE.pdf: 3319263 bytes, checksum: 51b79bea8bd5a5a042d4db215bfe1a86 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-02-15T14:52:02Z (GMT) No. of bitstreams: 1 JonasOF_TESE.pdf: 3319263 bytes, checksum: 51b79bea8bd5a5a042d4db215bfe1a86 (MD5) / Made available in DSpace on 2017-03-21T14:53:47Z (GMT). No. of bitstreams: 1 JonasOF_TESE.pdf: 3319263 bytes, checksum: 51b79bea8bd5a5a042d4db215bfe1a86 (MD5) Previous issue date: 2016-08-29 / Sunflower adapts to different conditions of climate and soil, including the prevailing climate in the Northeast, but the water needs, as well as nitrogen fertilizer recommendations are not yet fully defined. The objective of this study was to evaluate sunflower productivity and efficiency of water and nitrogen use. The experiment was conducted between October 2013 to January 2014 in Unidade Agrícola Industrial Escola do Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte (IFRN/Campus Apodi), Apodi, in the state of Rio Grande do Norte, Brazil. Statistical design used was in blocks in the 4 x 4 factorial scheme with four replications. The treatments consisted of four water slides 58, 80, 100 and 120% of crop evapotranspiration (ETc) associated with four doses of nitrogen 40, 100, 200 and 370% of the dose recommended for the cultivation of 70 kg ha-1. The depth water of 517 mm (108% ETc) associated with nitrogen dose of 77 kg ha-1 provided 91.3% of the maximum productivity, these being the doses recommended in the studied conditions. The oil productivity depending on depths water and nitrogen levels followed the trend surface function in oil yield of water depths and doses of nitrogen. The water factor was most limiting characteristics evaluated the nitrogen fertilization / O girassol se adapta a diferentes condições de clima e solo, inclusive ao clima predominante na Região Nordeste, porém, as necessidades hídricas, assim como as recomendações de adubação nitrogenada, ainda não estão perfeitamente definidas. Objetivouse com o presente estudo, avaliar a produtividade do girassol e a eficiência do uso da água e nitrogênio. O experimento foi conduzido no período de 29 outubro de 2013 a janeiro de 2014 na Unidade Agrícola Industrial Escola do Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte (IFRN/Campus Apodi), Apodi, RN. O delineamento estatístico adotado foi em blocos no esquema fatorial 4 x 4 com quatro repetições. Os tratamentos consistiram em quatro lâminas de irrigação 58, 80, 100 e 120% da evapotranspiração da cultura (ETc) associadas a quatro doses de nitrogênio 40, 100, 200 e 370% da dose padrão de 70 kg ha- 1. A lâmina de água de 517 mm (108% da ETc) associada a dose nitrogenada de 77 kg ha-1 proporcionou 91,3% da produtividade máxima de grãos, sendo estas as doses recomendadas nas condições estudadas. A produtividade de óleo em função das doses de água e nitrogênio acompanhou a tendência da superfície do rendimento de óleo em função das lâminas de água e doses de nitrogênio. As lâminas de água foram mais limitantes às características avaliadas que a adubação nitrogenada / 2017-02-14

La raréfaction des ressources en eau associée au changement climatique menace particulièrement la durabilité de la viticulture en climat Méditerranéen. Pour y faire face, la création ou le choix de cépages économes en eau et suffisamment vigoureux en cas de déficit hydrique se présente comme un levier important. Une compréhension approfondie des mécanismes qui gouvernent le maintien de l'état hydrique par la plante est indispensable pour avancer dans cette direction. Dans ce travail les déterminants génétiques et physiologiques de l'utilisation de l'eau ont été explorés chez la vigne. Une descendance F1, issue d'un croisement entre les cépages Syrah et Grenache, a été soumise à deux scénarios hydriques dans des pots (bonne irrigation et déficit modéré) en combinant de nouveaux outils de phénotypage, une démarche de génétique quantitative (pour la détection de QTLs) et des approches physiologiques. L'analyse de l'architecture génétique du maintien du potentiel hydrique par la plante, plus ou moins efficace en cas de déficit hydrique (i.e. iso- ou aniso-hydrique), a révélé un double déterminisme, impliquant non seulement la régulation stomatique de la transpiration mais également le maintien de la conductance hydraulique à travers la plante. Nous avons démontré l'existence d'une action indirecte de l'acide abscissique sur la fermeture stomatique à travers une diminution de la conductance hydraulique dans la feuille avec une variabilité génétique reliée aux comportements iso- ou aniso-hydriques. Par ailleurs, nous avons mis en évidence une variabilité génétique importante de la transpiration nocturne, liée à celle de l'efficience d'utilisation de l'eau, avec des déterminants génétiques et physiologiques que nous avons identifiés. Au-delà de l'utilité des QTLs détectés pour l'amélioration variétale, les résultats originaux de ce travail démontrent l'intérêt de la génétique quantitative pour progresser dans la compréhension de mécanismes physiologiques. / In Mediterranean regions, water scarcity associated with climate change particularly threatens the sustainability of viticulture. Breeding grapevine for reduced water use and maintained production is therefore of major interest. This requires a comprehensive knowledge of the plant physiological responses to drought. In this study we focused on the determinism of transpiration rate as a key trait regulating water status in plant tissues, and on its relationship with water-use efficiency (WUE). We used a F1 progeny from a cross between cultivars Syrah and Grenache and combined powerful phenotyping tools on potted plants submitted to either well-watered or mild deficit conditions with quantitative genetics (for QTL detection) and physiological experiments. Analysis of the genetic control of water status maintenance in the plant, more or less efficient under soil water deficit (i.e. iso- or anisohydric), revealed a dual physiological determinism with a key role for plant hydraulic conductance beside that of stomatal control of transpiration. An indirect role of abscisic acid on stomatal conductance was also evidenced, mediated by the downregulation of leaf hydraulic conductance, with a genetic variability which correlated with genetic variation in iso- or aniso-hydric behaviour. We then revealed wide genetic variations in nocturnal transpiration, which correlated with variations in water use efficiency, and identified corresponding genetic and physiological determinants. In a final switch to the field, we showed consistency between QTLs detected for daytime WUE in pots and in the vineyard. Beyond the potential interest of the QTLs detected in this study for breeding prospects, this work demonstrated the benefits of quantitative genetics to shed light on ecophysiological and physiological processes.

Fatores ambientais são determinantes nos processos fisiológicos das plantas de milho, no acúmulo de matéria seca e no rendimento da cultura. O objetivo desse trabalho foi avaliar as interações entre as variáveis ambientais com o crescimento, desenvolvimento e produtividade do milho (Zea mays L.) em quatro épocas de semeaduras, com destaque para a eficiência no uso da radiação e da água. Para tanto, um experimento de campo foi conduzido na região de Arapiraca, (09º48 55,1 S, 36º36 22,8 W e altitude de 236 m), Alagoas Brasil. O experimento foi conduzido, durante a estação chuvosa, de maio a outubro de 2008 com quatro épocas de semeadura. A primeira época de semeadura (T1) ocoreu no dia 06 de maio, a segunda (T2) no dia 19 de maio, a terceira no dia 10 de junho e a quarta no dia 30 de junho de 2008, utilizando a variedade Al Bandeirante. Os elementos meteorológicos foram medidos através de sensores, instalados na estação meteorológica localizada na área contígua ao experimento e os dados de umidade do solo foram capturados através de sensores, utilizando a reflectometria no domínio do tempo (TDR), coletadas durante a estação de crescimento da cultura. A evapotranspiração de referência (ETo), a evapotranspiração da cultura (ETc) e a evapotranspiração real (ETr) foram estimadas pela metodologia definida no Boletim FAO-56. A análise das interações agrometeorológicas do milho mostraram que a taxa de crescimento da cultura (TCC) em g m-2 dia-1, o índice de área foliar (IAF) no estádio fenológico de grãos farináceos (R4) e a produtividade de grãos foram menores na última época de semeadura (T4), quando comparadas às demais épocas (T1, T2 e T3). Já os valores da área foliar específica (AFE) não apresentaram diferenças entre si, para as quatro épocas de semeadura. A evapotranspiração real (ETr) variou de 356 mm, na primeira época de semeadura (T1) a 229,6 mm na última época (T4), enquanto a eficiência no uso da água (EUA) esteve no intervalo de 4,28 kg m-3 na terceira época (T3) a 3,76 kg m-3 de matéria seca, na quarta época de semeadura (T4). Na primeira época de semeadura (T1), verificou-se uma eficiência no uso da radiação (EUR) de 4,61 g de massa seca por MJ m-2 de radiação fotossinteticamente ativa absorvida (RFAabs), enquanto a quarta época (T4), contabilizou 2,98 g de massa seca por MJ m-2 de RFAabs, sendo 35,4% menor que T1. Diante das observações conclui-se que a menor produtividade foi verificada no tratamento T4, decorrente das modificações morfofisiológicas, ocorridas nas plantas de milho, causadas pelas alterações ambientais.