• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 158
  • 121
  • 103
  • 39
  • 37
  • 21
  • 16
  • 9
  • 6
  • 5
  • 3
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 588
  • 151
  • 113
  • 100
  • 98
  • 96
  • 94
  • 94
  • 60
  • 59
  • 54
  • 54
  • 52
  • 48
  • 46
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

Sprachkontakt und Sprachkompetenzen bei Bildungsausländer/-innen: Eine empirische Studie zum Zusammenhang zwischen Sprachkontakt und Sprachkompetenzen im Rahmen des Projektes „Sprache und Studienerfolg“ der Universitäten Leipzig und Würzburg

Grimmer, Anna 29 May 2021 (has links)
Die Frage, ob mehr Sprachkontakt automatisch zu mehr Sprachkompetenzen führt, wird und wurde in der Fremdspracherwerbsforschung bereits disziplinübergreifend diskutiert. Viele Pädagogen, Didaktiker und auch Studenten sehen in Auslandsaufenthalten die perfekte Möglichkeit, um in eine Fremdsprache einzutauchen und die fremdsprachlichen Kompetenzen in kurzer Zeit stark zu verbessern. Unter anderem stellen Segalowitz et al. (2004) fest, dass Studenten, die ein Auslandssemester absolvierten, am Ende zwar flüssiger sprachen, jedoch im Gegensatz zu den Kommilitonen, die nicht im Ausland waren, teilweise sogar weniger Kompetenzzuwachs im Bereich des Grammatikwissens vorweisen konnten. Die Aussage, mehr Sprachkontakt führe bei L2-Lernern automatisch zu besseren Sprachkompetenzen in der Zielsprache, ist somit unzulässig verallgemeinernd und trägt mitnichten der Komplexität des Spracherwerbsprozesses Rechnung. Im Rahmen der vorliegenden Masterarbeit möchte ich mich deshalb intensiver mit der Frage zum Einfluss des Sprachkontaktes auf die Entwicklung von Sprachkompetenzen beschäftigen.
162

Mango, Chili und Tomaten: Adventsaktion für das Olugamangalam-Gartenprojekt in Tamil Nadu

29 October 2019 (has links)
Dieses Jahr bitten wir um Unterstützung für ein Gartenprojekt in Tamil Nadu. Wir hoffen nicht nur auf ausreichend Spenden, sondern wünschen uns, dass wir mit diesem Projekt die Beziehung zur Partnerkirche des Leipziger Missionswerkes in Indien vertiefen können. Wir haben deshalb zum fünften Mal Begleitmaterial entwickelt. Die Bausteine in diesem Heft können Sie im Kindergarten, bei der Christenlehre oder im Kindergottesdienst verwenden. Angelehnt an die Adventszeit finden Sie vier Themenblöcke: Andachten, Geschichten, Lieder, Rezepte, Spiele und Bastelideen, die natürlich auch außerhalb der Adventszeit benutzt werden können.
163

Establishing the Value of ALS-Inhibiting Herbicides in Fields with Confirmed Weed Resistance to ALS-Inhibiting Herbicides

Jodi E Boe (6632369) 11 June 2019 (has links)
<p>Acetolactate synthase (ALS) inhibitors are a widely used class of selective herbicides used to control grass and broadleaf weeds. The repeated use of ALS-inhibiting herbicides has selected for biotypes of weeds resistant to ALS inhibitors, especially in the weeds most problematic to growers in the Midwest. While ALS inhibitor use seems futile, new mechanisms of herbicide action are not predicted to be commercialized in the near future to solve this problem. This leads to the main objective of this research, determining what value ALS inhibitors provide in controlling populations of weeds with resistance to ALS inhibitors. </p> <p>Field experiments with soil-applied (PRE) applications of ALS inhibitors on horseweed (<i>Erigeron canadensis</i>) and tall waterhemp (<i>Amaranthus tuberculatus </i>var. <i>rudis</i>) exhibited higher efficacy than would be expected given the frequency of the ALS resistance trait in the population. Whereas control of these species with POST-applied applications was similar or less than the proportion of the population characterized as susceptible using molecular techniques. Soil-applied applications, therefore, resulted in relatively greater control than POST applications in populations with known ALS-inhibitor-resistance mechanisms.</p> <p>Greenhouse experiments showed that overall resistance ratios were higher for PRE applications of ALS inhibitors in horseweed, tall waterhemp, and Palmer amaranth (<i>Amaranthus palmeri</i>). However, GR<sub>50</sub> values decreased for both susceptible and resistant biotypes for the PRE applications compared to POST, suggesting the biologically effective dose of these herbicides is lower in soil residual applications. This research found that PRE applications of ALS inhibitors resulted in some level of control on horseweed and tall waterhemp classified as resistant to ALS inhibitors due to the higher efficacy of PRE herbicide applications.</p> <p>Genetic analysis assessing the amino acid substitutions that confer resistance to ALS inhibitors in tall waterhemp confirmed a difference in selection pressure between PRE and POST applications and between ALS active ingredients in tall waterhemp. Applications of chlorimuron PRE at 11 g ai ha<sup>-1 </sup>selected for 35% homozygous W574L genotypes and at 44 g ha<sup>-1</sup> selected for 70% homozygous W574L genotypes. An increase of homozygous W574L individuals along with a decrease in heterozygous individuals from 65 (11 g ha<sup>-1</sup>) to 29% (44 g ha<sup>-1</sup>) suggests that W574L is semi-dominant in tall waterhemp and that high labeled rates of chlorimuron applied PRE can partially overcome the heterozygous W574L-resistance mechanism. In horseweed, no difference in selection pressure was observed between application timing or between chlorimuron or cloransulam. A new mutation conferring ALS-inhibitor resistance in horseweed was discovered, a Pro197Leu amino acid substitution, with resistance ratios of 21X to chlorimuron and 8.6X to cloransulam. These resistance ratios are slightly less than those reported for the Pro197Ala and Pro197Ser amino acid substitutions in conferring ALS-inhibitor resistance in horseweed. </p> <p>Finally, a survey of 42 populations of tall waterhemp in Indiana counties with confirmed ALS-inhibitor resistant populations of tall waterhemp found that all populations contained at least 16% individuals with the W574L amino acid substitution, 35 populations contained at least 1% individuals with the S653N substitution, and 9 populations contained at least 1% individuals with the S653T substitution. Taking into consideration the three mutations tested, 8 of the 42 populations tested contained <50% ALS-inhibitor resistant individuals within the population. Using the same tall waterhemp populations as collected in the survey, Next-Generation Sequencing was used to determine if other amino acid substitutions conferring resistance to ALS inhibitors existed. Results from WideSeq revealed that 10 other amino acid substitutions in the ALS protein may be conferring resistance in tall waterhemp in Indiana: A122T, A122N, A122S, P197T, P197L, P197H, D376E, and G654F. Further research from this survey also suggests that metabolic resistance to ALS inhibitors is likely a contributor to resistance in tall waterhemp in Indiana.</p> <p>This research suggests that ALS-inhibiting herbicides, more specifically chlorimuron, would provide the greatest contribution to management of tall waterhemp. Chlorimuron would perform best when used in soil residual applications and in populations of tall waterhemp containing either individuals susceptible to chlorimuron or individuals heterozygous for ALS inhibitor resistance conferred by the W574L mutation. This research also demonstrates the specificity of the amino acid substitutions in the ALS protein and by weed species to realize the benefit of these herbicides for management of weeds resistant to ALS inhibitors. Molecular characterization of target site resistance to ALS inhibitors has traditionally been considered relatively simple. However, we found 11 new amino acid substitutions that confer resistance to ALS inhibitors in horseweed and tall waterhemp. The complexity of ALS inhibitor resistance calls for the use of methods such as NGS to detect all potential resistance mutations in a timely manner and for the use of tests detecting metabolic resistance. Overall, this research demonstrates that ALS inhibitors still provide some utility for management of weed populations classified as resistant to ALS inhibitors and that the resistance mechanisms in horseweed and tall waterhemp are more numerous than previously reported. </p>
164

Respostas de cultivares de soja ao resíduo da mistura dos herbicidas imazapyr e imazapic / Answers of soybean cultivars to carryover of herbicides mixture imazapyr and imazapic

Fraga, Diego Severo 22 March 2016 (has links)
Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-05-02T13:55:51Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_diego_severo_fraga.pdf: 1548587 bytes, checksum: c109de985c27f806698e98816b90240d (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-05-02T17:57:09Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_diego_severo_fraga.pdf: 1548587 bytes, checksum: c109de985c27f806698e98816b90240d (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-05-02T17:58:55Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_diego_severo_fraga.pdf: 1548587 bytes, checksum: c109de985c27f806698e98816b90240d (MD5) / Made available in DSpace on 2017-05-02T17:59:16Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_diego_severo_fraga.pdf: 1548587 bytes, checksum: c109de985c27f806698e98816b90240d (MD5) Previous issue date: 2016-03-22 / Sem bolsa / A rotação da cultura da soja ao arroz irrigado e sucessão com azevém pode ser considerado opção para manejo de plantas daninhas em área de terras baixas, principalmente o arroz-vermelho. Além disso, o surgimento de novas tecnologias de soja resistente a herbicidas do grupo das imidazolinonas como a Cultivance® pode auxiliar o produtor de sementes no controle de plantas daninhas quando associadas a sistemas de manejo como “plante-aplique” e “aplique-plante”. Dessa forma, os objetivos da pesquisa foram avaliar a fitotoxicidade, os componentes da produtividade e a qualidade fisiológica das sementes de cultivares de soja contendo as tecnologias Cultivance®, tolerância a sulfonilureias e Roundup Ready®, frente ao resíduo de doses crescentes da mistura dos herbicidas imazapyr e imazapic, aplicado no manejo da cultura do arroz irrigado; avaliar a permanência do resíduo do herbicida no solo em virtude do acúmulo de massa da matéria seca da parte aérea de plantas de azevém, semeadas em sucessão com a cultura da soja; quantificar a atividade da enzima ALS em cultivares de soja resistentes ou suscetíveis ao herbicida imazapic; avaliar as alterações nos metabólitos secundários de plantas de soja contendo essas tecnologias, submetidas a mistura dos herbicidas imazapyr e imazapic nos sistemas de manejo “plante-aplique e “aplique-plante”. Para isso, foram realizados experimentos em campo, casa-de-vegetação e laboratório da Universidade Federal de Pelotas, Embrapa Clima Temperado e Embrapa Trigo, utilizando diferentes cultivares de soja submetidas ao herbicida imazapyr+imazapic. Os resultados demonstraram que a cultivar de soja contendo a tecnologia Cultivance® é resistente a mistura dos herbicidas imazapyr e imazapic aplicado no manejo do arroz irrigado, porém, as demais cultivares são suscetíveis. O resíduo do herbicida afeta a produtividade e a qualidade fisiológica da semente das cultivares estudadas. A massa da matéria seca da parte aérea do azevém, é reduzida na presença do resíduo do herbicida. O KM (concentração de piruvato) da enzima ALS das cultivares de soja são semelhantes, contudo o Vmáx (velocidade máxima da reação) da cultivar resistente é menor, comparado às demais, supondo-se que a resistência da cultivar contendo a tecnologia Cultivance® pode ser decorrente da insensibilidade da enzima ALS ao herbicida imazapic. As cultivares suscetíveis apresentam, em geral, maior teor de clorofila e sofrem maior ação das espécies reativas de oxigênio, comparadas a resistente. A elevação da dose da mistura dos herbicidas imazapyr e imazapic aumenta a ação do sistema antioxidante enzimático, por meio das enzimas superóxido dismutase, catalase e ascorbato peroxidase, independente do sistema de manejo. / Soybean crop rotation with irrigated rice and sucession with ryegrass may be considered an option to weed management in flooded area, mainly for red rice. Besides that new technologies appearance of soybean herbicide resistant of imidazolinone group such as Cultivance® may help seed farmers in the weed control when associated to management systems such as “plant-apply” and “apply-plant”. Thus the reseach objectives were evaluate phytotoxicity, yield components and physiological quality of soybean seeds’ cultivars containing Cultivance®, sulfonylurea tolerant and Roundup Ready® technologies, as affected by carryover of increasing doses of mixture of herbicides imazapyr and imazapic spraying in management of irrigated rice crop; evaluate herbicide carryover in soil due ryegrass shoot dry matter, seeded in sucession with soybean crop; quantify ALS enzyme activity in soybean cultivars resistants or susceptibles to imazapic herbicide; evaluate the changes on secondary metabolism of soybean plants containing these technologies, submmited to mixture of herbicides imazapyr and imazapic in “plant-apply” and “apply-plant” management systems. Therefore experiments were performed on field, greenhouse and laboratories in the Federal University of Pelotas, Embrapa Temperate Climate and Embrapa Wheat, using differents soybean cultivars submmited to imazapyr+imazapic herbicide. The results showed that soybean cultivar containing Cultivance® technology is resistant to mixture of herbicides imazapyr and imazapic sprayed in management of irrigated rice, but the others cultivars are susceptibles. The herbicide carryover affect the crop yield and physiological quality of seed of the studied cultivars. Ryegrass shoot dry matter is affected by herbicide carryover. ALS enzyme KM (pyruvate concentration) of soybean cultivars are similar, however the Vmáx (maximum reaction speed) of resistant cultivar is minor, compared with the other cultivars, supposing that the resistance of the cultivar containing Cultivance® technology may be due insensibility ALS enzyme to imazapic herbicide. The susceptibles cultivars show, in general, more chlorophyll and suffer more action of reactives oxygen species, compared to resistant. The increasing dose of mixture of herbicides imazapyr and imazapic enhance the action of enzymatic antioxidant system, by means of superoxide dismutase, catalase and ascorbate peroxidase enzymes, independent of management system.
165

"Cool my doubt is erased": constructive disagreement and creating a psychologically safe space in multicultural student teamwork

Komori-Glatz, Miya January 2018 (has links) (PDF)
This paper investigates the roles of disagreement and trust in multicultural teamwork on an English-medium master's programme at an Austrian business university. The teamwork project - assigned by the content teacher - took place mostly outside the classroom and simulated business practice both in terms of the tasks and the multicultural context. Each team comprised two Austrian students and two international students, resulting in an English as a lingua franca (ELF) setting. The teams were observed and audio-/video-recorded, with the analysis focusing on an early stage of the project where they laid the groundwork for the team mental models in terms of establishing the team goals, relationships and communicative practices. Additionally, retrospective interviews were conducted at the end of the project with each of the team members and the lecturer to gain emic insights into the project. The findings suggest a symbiotic relationship between disagreement and trust, in which high levels of trust and the construction of a psychologically safe space allow the team members to disagree with and challenge each other without damaging their relationships, leading to better decisions. In turn, these decisions can contribute to a sense of shared success that strengthens the team's joint identity.
166

La interpretació als serveis públics des d'una perspectiva ética: La deontologia professional i l'aplicació al context penitenciari

Baixauli Olmos, Lluís 02 July 2012 (has links)
Aquesta tesi doctoral estudia la professió de la interpretació als serveis públics (ISP) des del punt de vista de l'ètica, tot aprofundint en el marc deontològic que dirigeix la praxi i la seua aplicació a una àrea delimitada d'especialització, la interpretació penitenciària. Amb la finalitat d'analitzar el marc normatiu general de la ISP, s'ha estudiat set documents deontològics (codis deontològics, codis de conducta i normes de pràctica) en vigor. Els factors que defineixen l'àmbit d'interpretació específic s'han determinat per mitjàde l'observació del context, d'entrevistes i de qüestionaris als diversos agents implicats. La hipòtesi principal del treball planteja que l'estudi de l'ètica professional a través dels documents deontològics aporta informació útil per fer emergir un entramat d'estructures i relacions semàntiques, subjacents als documents, que serveixen per caracteritzar la ISP en general i els diversos contextos de treball. La descripció d'un context de treball, com el penitenciari, pot servir per afinar l'ètica general d'acord amb les característiques ambientals. Com una primera aproximació de tipus formal als documents deontològics estudiats, s'aporta una descripció del gènere textual. Així mateix, es realitza una anàlisi semàntica dels documents, especialment des d'una perspectiva ètica (el sistema moral), però també socioprofessional (les estructures i processos que el col·lectiu ha instaurat per controlar el camp) i tècnica (les estratègies pròpies del camp de la ISP que la comunitat professional recomana). Aquestos tres eixos conformen un marc d'anàlisi adequat per a la caracterització moral de la ISP. A continuació, es presenta una descripció del context penitenciari de la ISP a partir de les estructures semàntiques extretes dels documents deontològics. S'observa una majoria d'àrees de convergència entre el marc deontològic general i els territoris "inexplorats" de la pràctica de la ISP. Això no obstant, categories com l'"espai" reben una atenció mínima en els documents deontològics, tot i ser un element contextual que afecta directament a la ISP, concretament a l'ambient emocional, el tipus de relacions entre els participants primaris, el rol dels intèrprets i algunes de les dificultats més importants que aquests acaren. D'altra banda, la ISP penitenciària es veu clarament condicionada pels procediments de seguretat, que es revela com el tret distintiu principal. Finalment, es proposa una valoració del treball i vies futures d'estudi i d'acció.
167

Χρήση του προτύπου MPEG-4 ALS και διακαναλλική πρόβλεψη για κωδικοποίηση πολυκαναλλικού ηλεκτροκαρδιογραφήματος

Κωνσταντίνου, Ιωάννης 03 July 2009 (has links)
Είναι γεγονός ότι το ηλεκτροκαρδιογράφημα είναι ένα πολύ καλά μελετημένο σήμα. Ειδικά τα τελευταία χρόνια, έχει προταθεί ένας μεγάλος αριθμός αλγορίθμων επεξεργασίας, συμπίεσης, αυτόματης διάγνωσης, φιλτραρίσματος, αποθορυβοποίησης και κωδικοποίησης. Σ’ αυτή τη διπλωματική εργασία, προτείνουμε ένα αποδοτικό αλγόριθμο κωδικοποίησης χωρίς απώλειες για δεδομένα από δωδεκακάναλλο ηλεκτροκαρδιογράφημα. Ο κωδικοποιητής υλοποιεί ένα πολυγραμμικό μοντέλο υψηλής απόδοσης, το οποίο είναι «ειδικευμένο στους ασθενείς», ενδοκαναλικής πρόβλεψη και εφαρμόζει το πρότυπο κωδικοποίησης MPEG-4 ALS για διακαναλική πρόβλεψη και κωδικοποίηση. Τα αποτελέσματα του αλγορίθμου συγκρίθηκαν με τεχνικές κωδικοποίησης εντροπίας χωρίς απώλειες και δείχνουν αύξηση της απόδοσης κωδικοποίησης. / The Electrocardiogram (ECG) is one of the most well studied medical signals. A large number of ECG processing algorithms have being proposed over the years covering the areas of ECG noise filtering, automated diagnostic interpretation and coding. In this master thesis, we propose a robust multi-channel ECG encoder architecture, which operates on 12-channel ECG data. The encoder utilizes highly efficient multi-linear patient specific models for inter-channel prediction and the MPEG-4 Audio Lossless Coding (ALS) architecture for intra-channel prediction and coding. The results of the algorithm show improved performance over standard encoding techniques.
168

Mitochondrial metabolism in hypoglossal motoneurons from mouse – implications for amyotrophic lateral sclerosis (ALS) / Mitochondrialer Metabolismus in hypoglossalen Motoneuronen der Maus - Bedeutung für die Amyotrophe Lateral Sklerose (ALS)

Bergmann, Friederike 12 February 2004 (has links)
No description available.
169

Zuhören lernen - die didaktische Funktion des Hörens im Religionsunterricht zwischen überfachlicher Kompetenz und Kompetenzen religiöser Bildung

Wegener, Judith 29 August 2017 (has links) (PDF)
In der Dissertation wird die Frage nach einer überfachlichen Zuhörkompetenz, ihrem Verhältnis zu Kompetenzen religiöser Bildung sowie nach Möglichkeiten beides im Religionsunterricht zu fördern, gestellt. Bezugspunkte bilden dabei die Lernkompetenz nach Czerwanski et al. sowie der Orientierungsrahmen der EKD für die Sekundarstufe I. Nach der Darstellung des Forschungsstandes wird Hören/Zuhören in Beziehung zu Wahrnehmung, Ästhetischer Bildung sowie Evangelischer Bildungstheorie gesetzt und damit der bildungstheoretische Bezugsrahmen der Thematik beschrieben. An praktischen Beispielen aus dem Unterricht können anschließend die verschiedenen Zuhörarten in ihrer Relevanz für den Religionsunterricht gezeigt werden, bevor die besondere Bedeutung des Hörens im religiösen Kontext untersucht wird. Die in den vorherigen Kapiteln erarbeiteten Ergebnisse werden schließlich in Form von Thesen anhand einer per Video aufgezeichneten und transkribierten Unterrichtseinheit einer Lerngruppe der Klassenstufe 5 überprüft. Dabei steht die Frage nach konkret in dieser Unterrichtseinheit geförderten Teilkompetenzen einer überfachlichen Zuhörkompetenz sowie Kompetenzen religiöser Bildung im Vordergrund. Den Abschluss bildet der Entwurf eines Kompetenzmodells, das die systematische Förderung des Zuhörens im Religionsunterricht möglich macht. Im Abstract genannte Literatur: Czerwanski, Annette/ Solzbacher, Claudia/ Vollstädt, Wittloff (Hg.): Förderung von Lernkompetenz in der Schule. Bd. 1. Recherche und Empfehlungen, Gütersloh (Verlag Stiftung Bertelsmann) 2002. Kirchenamt der Evangelischen Kirche in Deutschland (Hg.): Kompetenzen und Standards für den Evangelischen Religionsunterricht in der Sekundarstufe I. Ein Orientierungsrahmen, Hannover 2010.
170

Alterações fisiológicas e morfológicas de duas cultivares de arroz irrigado após aplicação do herbicida imazamox na fase reprodutiva / Physiological and morphological changes of two rice cultivars after imazamox herbicide application in reproductive phase

Moraes, Bibiana Silveira 01 March 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Weed control is one of the main agricultural practices indispensable to ensure profitability and crop success. In paddy rice field, red rice is the most important weed due to its difficult control. A widespread control method is the use of rice cultivars resistant to herbicides which are inhibitors of ALS, since it is possible to have a selective chemical control. Studies showed that the late control with imazamox promotes efficient control of red rice escapes. Thus, the objective of this research was to check the effects of imazamox application in the reproductive phase of two rice cultivars that differ in the level of resistance to imidazolinones. Two studies were carried out at the Federal University of Santa Maria in the years of 2009/10 and 2010/11. Imazamox was applied in different stadium of development and doses. At the end of the application the final dose was 80 g a.i ha-1 for all treatments. Results showed that independent of the date of the imazamox application in the reproductive phase of rice, the grain yield reduced and spikelet sterility of IRGA 422 CL increased. In general, the parameters 1000-grain weight, flag leaf length, panicule length, fresh and dry weight of panicles, and panicles per m2 showed a reduction in practically all imazamox treatments in the IRGA 422 CL cultivar. Changes in the biochemical parameters (chlorophyll, carotenoids, thiobarbituric acid reactive substances, superoxide dismutase, catalase and ascorbate peroxidase) were observed in leaves and panicles from main culm in some treatments, demonstrating that the oxidative stress promoted by imazamox may have contributed to grain yield reduction and the high percentage of sterile spikelet from IRGA 422 CL cultivar. Morphologic and anatomical changes showed that imazamox application in the panicle differentiation promoted similar changes to homeotic changes observed in rice mutant. Moreover, in the other treatments different morphologic and anatomical changes were observed. Therefore, morphologic and anatomical changes were likely to be responsible for grain yield reduction and high percentage of spikelet sterile from IRGA 422 CL. / O controle de plantas daninhas é uma das práticas agrícolas indispensáveis para garantir rentabilidade e sucesso no cultivo. No cultivo de arroz irrigado, o arroz vermelho é a planta daninha de maior importância, devido sua dificuldade de controle. Um método de controle bastante difundido é o uso de cultivares resistentes aos herbicidas inibidores da ALS, pois permite um controle químico seletivo. Estudos demonstram que o controle tardio com o herbicida imazamox promove controle eficiente de escapes de arroz vermelho. Por isso, o objetivo deste trabalho foi verificar os efeitos da aplicação do imazamox na fase reprodutiva de duas cultivares de arroz irrigado (IRGA 422 CL e PUITÁ INTA CL) que diferem quanto ao nível de resistência as imidazolinonas. Em vista do exposto, foram conduzidos dois estudos na área experimental da Universidade Federal de Santa Maria (2009/10 e 2010/11). O imazamox foi aplicado em diferentes estádios de desenvolvimento e doses, sendo que a dose final foi de 80 g i.a ha-1. Com os resultados obtidos conclui-se que independente da data de aplicação do imazamox na fase reprodutiva da cultura ocorreu redução da produtividade de grãos e aumentou a esterilidade de espiguetas da cultivar IRGA 422 CL. De maneira geral, os parâmetros: peso de mil grãos, comprimento da folha bandeira, comprimento de panícula, peso fresco e seco de panículas, e número de panículas por metro quadrado mostraram redução em praticamente todos os tratamentos na cultivar IRGA 422 CL. Alterações nos parâmetros bioquímicos (clorofila, carotenoides, substâncias reativas ao ácido tiobarbitúrico, superóxido dismutase, catalase e ascorbato peroxidase) foram observadas em folhas e panículas do colmo principal em alguns tratamentos, demonstrando que o estresse oxidativo provocado pela aplicação do imazamox pode ter contribuído para a redução da produtividade de grãos e o elevado percentual de espiguetas estéreis da cultivar IRGA 422 CL. A cultivar PUITÁ INTA CL não sofreu alterações em todos os parâmetros avaliados neste estudo. As alterações morfológicas e anatômicas demonstraram que a aplicação de 80 g i.a ha-1 imazamox na diferenciação da panícula promoveu alterações semelhantes às alterações homeóticas observadas em arroz mutante. Além disso, nas plantas que receberam a dose de 80 g i.a ha-1 após 14 dias da diferenciação do primórdio floral (DPF) e as plantas que receberam a dose de 80 g i.a ha-1 em aplicação fracionada (metade da dose 7 dias após DPF e metade da dose aos 14 dias após DPF) mostraram alterações morfológicas e anatômicas do grão de pólen. Dado o exposto, os resultados obtidos sugerem que as alterações morfológicas e anatômicas foram responsáveis pela redução da produtividade de grãos e alto percentual de espiguetas estéreis da cultivar IRGA 422 CL.

Page generated in 0.0316 seconds