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  • 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.
11

In-field variation for corn emergence and development /

Hager, Joshua W. January 2004 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.
12

Soil aggregate and organic matter dynamics in reclaimed mineland soils

Wick, Abbey Foster. January 2007 (has links)
Thesis (Ph.D.)--University of Wyoming, 2007. / Title from PDF title page (viewed on July 26, 2010). Includes bibliographical references.
13

In-field variation for corn emergence and development

Hager, Joshua W. January 2004 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.
14

Variability of soil hydraulic properties and estimation of plant-available water on claypan-soil landscapes

Jiang, Pingping, January 2007 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 25, 2007) Vita. Includes bibliographical references.
15

Behaviour of ¹³⁷Cs and ⁹⁰Sr in agricultural soils : influence of ageing and soil type on availability, migration and plant uptake /

Forsberg, Sverker, January 1900 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.
16

Ionic balance and the constituent organic acids of current-year foliage of western redcedar, western hemlock, and Douglas-fir seedlings /

Graff, Joseph Edward. January 1993 (has links)
Thesis (Ph. D.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 109-125). Also available on the World Wide Web.
17

Detecting the trends in meteorological variables and investigating their effects on runoff over the last 50 years.

Madaeni, Fatemehalsadat January 2012 (has links)
There is now a general consensus among scientists on occurrences of more and intense climatic disasters, floods and droughts, everywhere in the future. To act sooner and smarter against these negative impacts, we must shift our focus in better understanding of the future climate change and possible implications of that to better manage our water resources. Certainly, there is a link between the future effects of climate change on water resources and trends of climatic variables. In this study, by using Mann-Kendall trend analysis method, it is concluded that from 1961 to 2010 only temperature has an upward trend, in all the seasons and yearly, in all the 16 studied stations from north, middle and south of Sweden. Furthermore, runoff simulated by HBV model shows increasing trend in summer and winter which is in partially agreement with the recorded one that discerns a growth in the mentioned seasons, as well as yearly. What is more, potential evapotranspiration estimated by FAO Penman-Monteith equation and actual one simulated by CoupModel reveal a rise in spring for the former and both spring and winter for the latter. Other meteorological variables do not show any significant trend, while intensive precipitation increased in winter and summer in the majority of the stations. Comparing the runoffs simulated by CoupModel and HBV model shows that HBV works better for three selected stations which can enforce the claim that HBV works better for smaller fields.
18

Wechselwirkung Bodenschutz - Pflanzenschutz - Düngung

Rößler, Iris, Nowack, Anja, Thate, Andela 21 December 2011 (has links)
In sächsischen Betrieben wurde bei unterschiedlichen Bodenbearbeitungssystemen die Wechselwirkung zwischen Bodenbearbeitung, Nährstoffversorgung und Pflanzenschutz untersucht. Bei den Bodenbearbeitungssystemen »Pfluglos« und »Konventionell« wurde die Wirkung auf das Nährstoffverhalten im Boden, auf das Nützlingsvorkommen, die Unkrautzusammensetzung und auf pilzliche sowie tierische Schaderreger beurteilt. Es zeigt sich, dass eine zu enge Fruchtfolge die Pflanzenschutzprobleme verschärft. Die Bodenbearbeitung hat entscheidenden Einfluss auf die Artenzusammensetzung, Artenzahl und Unkrautdichte. Das Durchwuchsproblem, eines der Hauptprobleme der nicht wendenden Bodenbearbeitung, mit reduziertem Herbizidaufwand in den Griff zu bekommen, ist nur begrenzt möglich. Im Winterweizen tritt Septoria tritici, DTR und Ährenfusarium bei nicht wendender Bodenbearbeitung mit Vorfrucht Mais oder Stoppelweizen verstärkt auf. Dauerhaft Pfluglos-Flächen der Lössstandorte zeigen einen höheren Gesamt-Behandlungsindex bei Winterweizen. Pfluglose Flächen haben ein höheres Vorkommen an Feldmäusen und Ackerschnecken.
19

Variação sazonal da fotossíntese e relações hídricas de laranjeira 'Valência' / Seasonal variation of photosynthesis and water relations of ‘Valencia’ sweet orange plant

Ribeiro, Rafael Vasconcelos 21 July 2006 (has links)
Esse estudo tem como hipótese que a variação sazonal da fotossíntese de laranjeira ‘Valência’ está relacionada a fatores ambientais e endógenos. A menor atividade fotossintética durante os meses frios e secos está possivelmente associada à baixa temperatura e ao acúmulo de reservas, podendo ocorrer mesmo em condições de boa disponibilidade hídrica. A alta atividade fotossintética durante os meses quentes e chuvosos é possivelmente induzida pela maior disponibilidade de recursos naturais (água, energia solar e temperatura) e maior demanda por carboidratos, haja vista que nessa ocasião ocorre fluxo vegetativo intenso. O objetivo foi testar a hipótese acima, avaliando a variação anual de algumas características fisiológicas relacionadas à fotossíntese (trocas gasosas, fluorescência da clorofila, potencial de água no ramo e conteúdo foliar de carboidratos) de laranjeiras ‘Valência’ em condições de campo, em Cordeirópolis (SP). A influência da baixa disponibilidade hídrica sazonal foi verificada comparando-se plantas em condições naturais com plantas sob irrigação. A produção e algumas características biométricas foram avaliadas. A maior atividade fotossintética de laranjeiras ‘Valência’ ocorre durante a primavera, sendo induzida pelo aumento da temperatura e disponibilidade hídrica, enquanto que a menor fotossíntese ocorre durante o inverno, quando há baixa temperatura e deficiência hídrica. Durante o inverno, a menor fotossíntese não é associada ao conteúdo total de reservas foliares. Os valores máximos de assimilação de CO2 são observados na primavera, quando as condições ambientais são intermediárias entre o verão e o inverno e há fluxos vegetativo e reprodutivo nas laranjeiras. A alta demanda de carboidratos por esses drenos causa decréscimos no conteúdo de reservas foliares entre outubro e novembro, possivelmente estimulando a fotossíntese na primavera. Embora a fotossíntese das plantas no verão seja maior que no inverno, a atividade fotossintética não alcança valores próximos aos da primavera por limitações de origem bioquímica e estomática. A menor atividade bioquímica é induzida pela maior temperatura do ar em relação à primavera, em especial durante o período vespertino, enquanto que a limitação de origem estomática é causada pela alta demanda evaporativa do ar no verão. Durante o período quente e chuvoso, a atividade fotoquímica se ajusta às condições ambientais e não limita a fixação de carbono. A menor atividade fotossintética durante o inverno é ocasionada pela menor condutância estomática, devida à baixa temperatura do ar e solo. A ocorrência de deficiência hídrica no inverno causa redução do potencial de água nos ramos, diminuindo ainda mais a condutância estomática. No inverno, há limitação bioquímica da fotossíntese devida à baixa temperatura do ar, indicada pela redução da eficiência instantânea de carboxilação. Em relação ao metabolismo fotoquímico, não há indícios de limitação da fotossíntese. / This study has as hypothesis that the seasonal variation of photosynthesis in ‘Valencia’ sweet orange plant is related to environmental and endogenous factors. The lower photosynthetic activity during cold and dry months is possibly associated to low temperature and accumulation of leaf reserves, occurring even in well-watered plants.The higher photosynthetic activity during warm and rainy months is probably induced by higher availability of natural resources (water, sunlight and temperature) and by carbohydrate demand, since there is intense vegetative flush during this period. The objective was to test the above hyphotesis, evaluating the annual variation of some physiological characteristics related to photosynthesis (gas exchange, chlorophyll fluorescence, stem water potential and leaf carbohydrate content) of ‘Valencia’ sweet orange plants under field conditions, in Cordeirópolis (SP). The influence of low seasonal water availability was verified by comparing plants under natural with irrigated plants. Fruit production and some biometric characteristics were evaluated. The highest photosynthetic activity in ‘Valencia’ sweet orange plants occurred in spring, being induced by increase of temperature and water availability, while the lowest photosynthesis occurred in winter, when there is low temperature and water deficiency. During the winter, the lowest photosynthesis is not associated to the total reserve content in leaves. The maximum CO2 assimilation values are observed in spring, when environmental conditions are intermediate between summer and winter and there are vegetative and reproductive flushes in sweet orange plants. The high demand for carbohydrates in those sinks causes reduction in leaf reserve contents between october and november, probably estimulating the photosynthesis in spring. Although the photosynthesis in summer is higher than in winter, the photosynthetic activity does not reach values close to ones observed in spring due to biochemical and stomatal limitations. The low biochemical activity is induced by higher air temperature when compared to spring, mainly during afternoon, while the stomatal limitation is caused by the high air evaporative demand in summer. During the warm and wet period, the photochemical activity adjusts itself to environmental conditions and does not limit the carbon fixation. The low photosynthetic activity during winter is caused by low stomatal conductance as a consequence of low air and soil temperature. The occurrence of water deficiency in winter causes reduction of stem water potential, which is an additional factor leading to reduced stomatal conductance. In winter, there is biochemical limitation of photosynthesis due to low air temperature, as indicated by reduced instantaneous carboxylation efficiency. Regarding the photochemical metabolism, there are not signs of limitation to photosynthesis.
20

Produtividade do milho após dessecação antecipada da pastagem degradada com e sem aplicação de cama de aviário / Maize productivity after early desiccation of degraded pasture with and without application of aviary bed

Souza, Leonardo Camillo Grosso de 10 October 2018 (has links)
Submitted by Michele Mologni (mologni@unoeste.br) on 2019-01-24T16:56:25Z No. of bitstreams: 1 Leonardo Camillo Grosso de Souza.pdf: 620949 bytes, checksum: 9b5db07b2086b97ee45f36346e5bf5b4 (MD5) / Made available in DSpace on 2019-01-24T16:56:25Z (GMT). No. of bitstreams: 1 Leonardo Camillo Grosso de Souza.pdf: 620949 bytes, checksum: 9b5db07b2086b97ee45f36346e5bf5b4 (MD5) Previous issue date: 2018-10-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this work was to evaluate the effects and consequences of the desiccation periods of the Urochloa brizantha cv. Marandú degraded, combined or not with application of bed of aviary on the chemical characteristics of the soil, the nutritional state of the plants and the yield of maize grains. The experiment was conducted at the experimental farm of Universidade do Oeste Paulista - UNOESTE, located in the municipality of Presidente Bernardes - SP, in a soil classified as Dystrophic Red Argissolo. The experimental design was a randomized complete block design with four replications. The plots consisted of five forage desiccation periods (60, 90,120, 150 and 180 days before maize sowing) and the subplots with and without aviary beds. The following evaluations were performed: soil chemical analysis (0-10, 10-20, and 20-40 cm); dry mass of straw; nitrogen carbon ratio (C / N) of straw; emergence of plants; height of flowering plants; leaf diagnosis; number of grains per spike; mass of one hundred grains; and corn yield. Maize yield was higher when desiccation of Urochloa brizantha cv. Degraded marandú was performed at 180 days before maize sowing. The 180-day interval between desiccation of Urochloa brizantha cv. Degraded marandú and maize sowing increased the levels of P, K, Ca and Mg of the soil. The time indicated for desiccation of Urochloa brizantha cv. Degraded marandú was of 90 days before the sowing of the corn when it was not applied bed of aviary. The application of litter bed did not interfere with maize productivity. / O trabalho teve o objetivo de avaliar os efeitos e consequências das épocas de dessecação da pastagem Urochloa brizantha cv. Marandú degradada, combinadas ou não com aplicação de cama de aviário sobre as características químicas do solo, o estado nutricional das plantas e a produtividade de grãos de milho. O experimento foi conduzido na fazenda experimental da Universidade do Oeste Paulista – UNOESTE, localizada no município de Presidente Bernardes – SP, em um solo classificado Argissolo vermelho distrófico. O delineamento experimental foi em blocos ao acaso em esquema de parcelas subdivididas, com quatro repetições. As parcelas foram constituídas por cinco épocas de dessecação da forrageira (60, 90,120, 150 e 180 dias antes da semeadura do milho) e as subparcelas com e sem cama de aviário. Foram realizadas as seguintes avaliações: análise química do solo (0-10; 10-20; e 20-40 cm); massa seca da palhada; relação carbono nitrogênio (C/N) da palhada; emergência de plantas; altura de plantas no florescimento; diagnose foliar; numero de grãos por espiga; massa de cem grãos; e produtividade do milho. A produtividade do milho foi maior quando a dessecação da Urochloa brizantha cv. Marandú degradada foi realizada aos 180 dias antes da semeadura do milho. O intervalo de 180 dias entre a dessecação da Urochloa brizantha cv. Marandú degradada e a semeadura do milho aumentou os teores de P, K, Ca e Mg do solo. A época indicada para a dessecação da Urochloa brizantha cv. Marandú degradada foi de 90 dias antes da semeadura do milho quando não foi aplicado cama de aviário. A aplicação de cama de aviário não interferiu na produtividade do milho.

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