Doctor of Philosophy / Department of Geography / Douglas G. Goodin / In this research, proximal measurements of hyperspectral reflectance were used to develop models for estimating chlorophyll content in tallgrass prairie at leaf and canopy scales. Models were generated at the leaf scale and then extended to the canopy scale. Three chlorphyll estimation models were developed, one based on reflectance spectra and two derived from derivative transformations of the reflectance spectra. The triangle chlorophyll index (TCI) model was derived from the reflectance spectrum, whereas the first and second derivative indices (FDI and SDI) models were developed from the derivative transformed spectra. The three models were found to be well- correlated with the chlorophyll content measured with solvent extraction. The result indicated that the three models were effective for the leaf scale estimates of chlorophyll content. The three chlorophyll models developed at the leaf scale were further extended to the canopy scale and fine-scale images. The three models were found to be conditionally effective for estimating canopy chlorophyll content. The TCI model was more effective in dense vegetation, and the FDI and SDI models were better in sparser vegetation. This research suggests that the extension of chlorophyll models from the leaf scale to canopy scale is complex and affected not only by soil background, but also by canopy structure and components

O déficit hídrico é um dos principais fatores limitantes da produtividade agrícola e a aplicação de alguns herbicidas específicos, no controle de plantas daninhas induz, como consequência de seus mecanismos de ação, um acúmulo de elétrons no fotossistema II, formando assim, radicais livres, que promovem a peroxidação dos lipídeos, que por sua vez destroem as membranas celulares, através do fenômeno conhecido como estresse oxidativo, semelhante ao provocado pela reação da planta submetida ao déficit hídrico O objetivo deste trabalho foi caracterizar fisiologicamente as variedades SP83-2847, SP83-5073, SP80-3280 e CTC2, submetidas a níveis de estresse oxidativo, ocasionados pela aplicação de doses do herbicida paraquat. O conteúdo relativo de clorofila (CC), a eficiência quântica potencial do fotossistema II (Fv/Fm), a nota visual de fitotoxicidade (NF) e a fitomassa fresca (MF) foram utilizados como parâmetros fisiológicos de avaliação. O estresse oxidativo foi imposto pela aplicação do herbicida paraquat nas doses 0 (D0), 25 (D1), 50 (D2), 100 (D3) e 200 (D4) g/ha de paraquat (1,1\'-dimetil-4,4\'-bipiridilio dicloreto). As avaliações foram realizadas nos períodos de 24, 48 e 960 horas após a aplicação dos tratamentos. O conteúdo relativo de clorofila (CC) estimado através do índice SPAD, a eficiência quântica potencial do fotossistema II (Fv/Fm), a nota visual de fitotoxicidade (NF) e a massa fresca (MF) são influenciados negativamente pelos tratamentos doses do paraquat. Os padrões de resposta ao estresse oxidativo ocasionado pela aplicação do paraquat nas variedades conhecidas como tolerantes ao déficit hídrico não indicam claramente que são diferentes dos padrões de resposta ao estresse oxidativo ocasionado pelo déficit hídrico, fato que não corrobora claramente com a hipótese de que variedades tolerantes ao estresse oxidativo ocasionado por herbicidas também seriam tolerantes ao déficit hídrico. / Drought is the main factor that limits crop yields, and the use of specific herbicides, to control weeds, induces, as a consequence of their mechanisms of action, an accumulation of electrons in the photosystem II, forming free radicals that promote the lipid peroxidation, hence destroying the cell membranes, by the known phenomenon oxidative stress, similar to the reaction of plants to drought. The objective of this study was to characterize physiologically the varieties SP83-2847, SP83-5073, SP80-3280 and CTC2, under levels of stress caused by the application of doses of the herbicide paraquat. The relative chlorophyll content (CC), the potential quantum efficiency of photosystem II (Fv / Fm), the visual rating of phytotoxicity (NF) and the fresh biomass (MF) were used as physiological parameters. Oxidative stress was imposed by the application of the herbicide paraquat at doses of 0 (D0), 25 (D1), 50 (D2), 100 (D3) and 200 (D4) g/ha of paraquat (1,1 \'-dimethyl -4,4 \'-bipyridylium dichloride). The evaluations were performed by periods of 24, 48 and 960 hours after treatment. The chlorophyll content (CC) estimated by the SPAD, the technique of potential quantum efficiency of photosystem II (Fv / Fm), phytotoxicity visual ratings (NF) and the fresh biomass (FM) are negatively influenced by treatments and doses of paraquat . The response patterns to oxidative stress caused by paraquat application of the known varieties tolerant to drought are not clearly indicate that are different form patterns of response to oxidative stress caused by drought, which did not clearly corroborates the hypothesis that tolerant varieties of oxidative stress caused by herbicides would also be tolerant to drought.

O déficit hídrico é o principal fator limitante na produtividade das culturas agrícolas. Com a crescente expansão da cultura canavieira rumo a regiões de marcantes déficits hídricos, torna-se essencial o desenvolvimento de variedades tolerantes a este tipo de estresse. O objetivo deste trabalho foi estudar os efeitos do déficit hídrico, em 20 variedades de cana-de-açúcar, visando identificar características para auxiliar o programa de melhoramento da cultura. O conteúdo relativo de clorofila, a eficiência quântica potencial do fotossistema II (Fv/Fm), o teor relativo de água (TRA), o incremento em altura dos colmos (IAC) foram utilizados como parâmetros fisiológicos além das características tecnológicas da matéria prima Brix e Pol. O déficit hídrico foi imposto pela suspensão da irrigação durante 3, 10 e 20 dias. O déficit hídrico reduziu o conteúdo relativo de clorofila, TRA, Fv/Fm, IAC e Pol para a maioria das variedades analisadas enquanto o teor de sólidos solúveis, mensurada através do Brix, não foi afetado. O período de suspensão de rega de 03 dias não foi suficiente para induzir déficit hídrico e, as melhores respostas para identificação de diferenças fisiológicas dentro de variedades foi obtida aos 20 dias. Não foi observado padrão de resposta que possa ser relacionado com o nível de tolerância das variedades para o resultado dos parâmetros IAC, TRA, Brix e Pol. Contudo constatou-se que os parâmetros Fv/Fm e conteúdo relativo de clorofila mostraram-se eficientes para diferenciar variedades de cana-de-açúcar tolerantes e sensíveis à deficiência hídrica. / Drought is a major limitation to crop productivity worldwide. The sugarcane is a crop in expansion towards areas of marked water deficit and it is essential the development of drought tolerant varieties. The aim of this work was to study the effects of drought in 20 sugarcane genotypes to identify parameters to improve the genotype screening in the breeding program. The relative chlorophyll content, potential quantum efficiency of photosystem II (Fv/Fm), the relative water content (TRA), the increase in height of stalks (IAC) were evaluated as physiological parameters in addition to the technological parameters Brix and Pol. The water deficit was imposed by withholding irrigation for 3, 10 and 20 days. The water deficit reduced the relative chlorophyll content, TRA, Fv/Fm, Pol and IAC for most varieties evaluated while the soluble solids content, measured by ° Brix, was unaffected. The withhold treatment of 03 days was not sufficient to induce water deficit and the best results to identify physiological differences within genotypes were obtained with 20 days. The IAC, TRA, Brix and Pol results were not related to the level of tolerance of genotypes. However, Fv/Fm and relative chlorophyll content traits were effective to distinguish between drought tolerant and susceptible sugarcane genotypes subjected to water stress.

O déficit hídrico é um dos principais fatores limitantes da produtividade agrícola e a aplicação de alguns herbicidas específicos, no controle de plantas daninhas induz, como consequência de seus mecanismos de ação, um acúmulo de elétrons no fotossistema II, formando assim, radicais livres, que promovem a peroxidação dos lipídeos, que por sua vez destroem as membranas celulares, através do fenômeno conhecido como estresse oxidativo, semelhante ao provocado pela reação da planta submetida ao déficit hídrico O objetivo deste trabalho foi caracterizar fisiologicamente as variedades SP83-2847, SP83-5073, SP80-3280 e CTC2, submetidas a níveis de estresse oxidativo, ocasionados pela aplicação de doses do herbicida paraquat. O conteúdo relativo de clorofila (CC), a eficiência quântica potencial do fotossistema II (Fv/Fm), a nota visual de fitotoxicidade (NF) e a fitomassa fresca (MF) foram utilizados como parâmetros fisiológicos de avaliação. O estresse oxidativo foi imposto pela aplicação do herbicida paraquat nas doses 0 (D0), 25 (D1), 50 (D2), 100 (D3) e 200 (D4) g/ha de paraquat (1,1\'-dimetil-4,4\'-bipiridilio dicloreto). As avaliações foram realizadas nos períodos de 24, 48 e 960 horas após a aplicação dos tratamentos. O conteúdo relativo de clorofila (CC) estimado através do índice SPAD, a eficiência quântica potencial do fotossistema II (Fv/Fm), a nota visual de fitotoxicidade (NF) e a massa fresca (MF) são influenciados negativamente pelos tratamentos doses do paraquat. Os padrões de resposta ao estresse oxidativo ocasionado pela aplicação do paraquat nas variedades conhecidas como tolerantes ao déficit hídrico não indicam claramente que são diferentes dos padrões de resposta ao estresse oxidativo ocasionado pelo déficit hídrico, fato que não corrobora claramente com a hipótese de que variedades tolerantes ao estresse oxidativo ocasionado por herbicidas também seriam tolerantes ao déficit hídrico. / Drought is the main factor that limits crop yields, and the use of specific herbicides, to control weeds, induces, as a consequence of their mechanisms of action, an accumulation of electrons in the photosystem II, forming free radicals that promote the lipid peroxidation, hence destroying the cell membranes, by the known phenomenon oxidative stress, similar to the reaction of plants to drought. The objective of this study was to characterize physiologically the varieties SP83-2847, SP83-5073, SP80-3280 and CTC2, under levels of stress caused by the application of doses of the herbicide paraquat. The relative chlorophyll content (CC), the potential quantum efficiency of photosystem II (Fv / Fm), the visual rating of phytotoxicity (NF) and the fresh biomass (MF) were used as physiological parameters. Oxidative stress was imposed by the application of the herbicide paraquat at doses of 0 (D0), 25 (D1), 50 (D2), 100 (D3) and 200 (D4) g/ha of paraquat (1,1 \'-dimethyl -4,4 \'-bipyridylium dichloride). The evaluations were performed by periods of 24, 48 and 960 hours after treatment. The chlorophyll content (CC) estimated by the SPAD, the technique of potential quantum efficiency of photosystem II (Fv / Fm), phytotoxicity visual ratings (NF) and the fresh biomass (FM) are negatively influenced by treatments and doses of paraquat . The response patterns to oxidative stress caused by paraquat application of the known varieties tolerant to drought are not clearly indicate that are different form patterns of response to oxidative stress caused by drought, which did not clearly corroborates the hypothesis that tolerant varieties of oxidative stress caused by herbicides would also be tolerant to drought.

Made available in DSpace on 2014-06-11T19:29:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-03-07Bitstream added on 2014-06-13T19:39:10Z : No. of bitstreams: 1 teixeirafilho_mcm_me_ilha.pdf: 330643 bytes, checksum: c3b27868589f79025ec907b8f416be35 (MD5) / A utilização de cultivares de trigo de alto potencial produtivo e a adubação nitrogenada são essenciais para obtenção de altas produtividades. Todavia, os estudos sobre a resposta dos componentes de produção e produtividade do trigo à adubação nitrogenada são insuficientes, e devem ser estudadas em condições específicas de ambiente, como a região dos cerrados de baixa altitude, onde há necessidade do uso da irrigação. O objetivo deste trabalho foi avaliar os efeitos de diferentes doses e fontes de N, sendo uma o sulfonitrato de amônio com inibidor de nitrificação (Entec), aplicadas totalmente em semeadura ou em cobertura, em diferentes cultivares de trigo irrigado, sob plantio direto. O experimento foi desenvolvido em área experimental pertencente à Faculdade de Engenharia de Ilha Solteira - UNESP, em Selvíria – MS, em um Latossolo Vermelho Distrófico. O delineamento estatístico foi o de blocos ao acaso, em esquema fatorial 5x3x2x4 (em 2006) e 5x3x2x2 (em 2007), ou seja, cinco doses de N (0, 50, 100, 150 e 200 kg ha-1), três fontes de nitrogênio (Entec, sulfato de amônio e uréia) e duas épocas de aplicação (semeadura ou cobertura). Em 2006, foram utilizados quatro cultivares de trigo (E 21, E 22, E 42 e IAC 370), com 3 repetições. Já em 2007, foram utilizados os cultivares E 21 e IAC 370, com 4 repetições. Os cultivares mais produtivos foram o IAC 370 e E 21. Não houve diferença entre o Entec, sulfato de amônio e uréia para produtividade de grãos e para maioria dos componentes de produção. A aplicação do N totalmente em semeadura ou em cobertura foram semelhantes no desempenho da cultura. O teor de N foliar e o teor de clorofila (SPAD) correlacionam-se positivamente, comprovando a relação nitrogênio e clorofila. As doses de nitrogênio influenciaram o teor de N foliar, teor de clorofila (SPAD) e aumentaram a produtividade de grãos... / The use of wheat cultivar of high productive potential and the nitrogen fertilization are essential to get high income. Though, the studies about the response of the production components and productivity of wheat to nitrogen fertilization are insufficient, and it should be studied in specific environmental conditions, as the savannah area of low altitude, where there is need the use of irrigation. The objective of this work was to evaluate the effects of different doses and sources of N, using one ammonium sulfonitrate with nitrification inhibitor (Entec), applied totally at sowing or at covering, in different wheat cultivars irrigated, under no till. The experiment was conducted at experimental area belonging to UNESP – Ilha Solteira Campus, located in Selvíria - MS, in an Acrustox. A randomized block design was used, in a factorial scheme 5x3x2x4 (in 2006) and 5x3x2x2 (in 2007), being five doses of N (0, 50, 100, 150 and 200 kg ha-1), three sources of nitrogen (Entec, ammonium sulfate and urea) and two application times (at sowing or at covering). In 2006, it was used four wheat cultivars (E 21, E 22, E 42 and IAC 370), with 3 repetitions. In 2007, it was used just the two best cultivars: E 21 and IAC 370, with 4 repetitions. The IAC 370 and E 21 wheat cultivars presented the highest productivity. There was no difference among Entec, ammonium sulfate and urea for grain yield and for majority of the production components. To the application of N totally at sowing or at covering it there was not difference between them. The N leaf and the chlorophyll contents (SPAD) were correlated positively, proving the relationship between nitrogen and chlorophyll contents. The doses of nitrogen influenced the N content, chlorophyll content (SPAD) and they increased the grain yield up to the dose of 118,5 kg ha-1 of N, independent of cultivar, source of N and application time.

O déficit hídrico é o principal fator limitante na produtividade das culturas agrícolas. Com a crescente expansão da cultura canavieira rumo a regiões de marcantes déficits hídricos, torna-se essencial o desenvolvimento de variedades tolerantes a este tipo de estresse. O objetivo deste trabalho foi estudar os efeitos do déficit hídrico, em 20 variedades de cana-de-açúcar, visando identificar características para auxiliar o programa de melhoramento da cultura. O conteúdo relativo de clorofila, a eficiência quântica potencial do fotossistema II (Fv/Fm), o teor relativo de água (TRA), o incremento em altura dos colmos (IAC) foram utilizados como parâmetros fisiológicos além das características tecnológicas da matéria prima Brix e Pol. O déficit hídrico foi imposto pela suspensão da irrigação durante 3, 10 e 20 dias. O déficit hídrico reduziu o conteúdo relativo de clorofila, TRA, Fv/Fm, IAC e Pol para a maioria das variedades analisadas enquanto o teor de sólidos solúveis, mensurada através do Brix, não foi afetado. O período de suspensão de rega de 03 dias não foi suficiente para induzir déficit hídrico e, as melhores respostas para identificação de diferenças fisiológicas dentro de variedades foi obtida aos 20 dias. Não foi observado padrão de resposta que possa ser relacionado com o nível de tolerância das variedades para o resultado dos parâmetros IAC, TRA, Brix e Pol. Contudo constatou-se que os parâmetros Fv/Fm e conteúdo relativo de clorofila mostraram-se eficientes para diferenciar variedades de cana-de-açúcar tolerantes e sensíveis à deficiência hídrica. / Drought is a major limitation to crop productivity worldwide. The sugarcane is a crop in expansion towards areas of marked water deficit and it is essential the development of drought tolerant varieties. The aim of this work was to study the effects of drought in 20 sugarcane genotypes to identify parameters to improve the genotype screening in the breeding program. The relative chlorophyll content, potential quantum efficiency of photosystem II (Fv/Fm), the relative water content (TRA), the increase in height of stalks (IAC) were evaluated as physiological parameters in addition to the technological parameters Brix and Pol. The water deficit was imposed by withholding irrigation for 3, 10 and 20 days. The water deficit reduced the relative chlorophyll content, TRA, Fv/Fm, Pol and IAC for most varieties evaluated while the soluble solids content, measured by ° Brix, was unaffected. The withhold treatment of 03 days was not sufficient to induce water deficit and the best results to identify physiological differences within genotypes were obtained with 20 days. The IAC, TRA, Brix and Pol results were not related to the level of tolerance of genotypes. However, Fv/Fm and relative chlorophyll content traits were effective to distinguish between drought tolerant and susceptible sugarcane genotypes subjected to water stress.

Air pollutant exposure poses a health risk to humans and impacts negatively on agriculture. High levels of air pollution resulted in extensive crop damage and yield reduction in Europe and USA. The Highveld region in South Africa, a very important area for maize and soya production, has already been declared an air pollution hot spot, with SO2 being the most concerning air pollutant. Most of the SO2 over the Highveld originates from the burning of coal for power generation. Developing countries, such as South Africa, are highly dependent on agriculture for food security and high levels of air pollution pose serious risks to the agricultural industry. Currently very little information is available on the effects of air pollution on crop production in South Africa. This study aimed to establish exposure-response relationship for SO2 on soybean and the quantification thereof on the morphological, physiological and biochemical characteristics. Two soybean cultivars were used, namely: LS 6164 and PAN 1666. The plants were fumigated for 7 hours, 7 days a week with 0 (carbon filtered control; CF), 25, 75 and 150 ppb SO2. The effect of SO2 was investigated on the growth, photosynthetic capabilities, photosynthetic gas exchange, peroxidase activity and lipoxygenase activity of the cultivars. Foliar injuries and interveinal chlorosis were visible with increasing levels of SO2 as well as a decrease in biomass accumulation, especially in root biomass; a more prominent feature of LS 6164. The number of nodules of both cultivars decreased insignificantly as the levels of SO2 increased. The number of pods per plant and the average weight of 30 seeds indicated a downward trend with an increase in SO2 concentration. The chlorophyll content of PAN 1666 was lower compared to LS 6164. PAN 1666 had the largest reduction in stomatal conductance at 150 ppb SO2 fumigation. The photosynthetic vitality index indicated that LS 6164 was more sensitive to SO2 inhibition from 25 ppb SO2 and higher, whereas PAN 1666 mostly became sensitive to SO2 from 75 ppb SO2. A decrease in the ability to absorb light energy, the trapping of excitation energy to transfer electrons beyond QA-, and the reduction of end electron acceptors all contributed to the decline in the vitality index. Sulphur content increased significantly in the 75 ppb and 150 ppb treatments of both cultivars. Induced peroxidase and lipoxygenase activity was seen in both cultivars, especially at higher concentrations of SO2 treatments. PAN 1666 had a higher rate of peroxidase and lipoxygenase activity compared to LS 6164. The implication for SO2 on crop production in the highly industrial Highveld area was demonstrated to be potentially of great concern. The dose-response relationships plotted for OJIP parameters emphasized that SO2 is an inhibitor of photosynthesis and phytotoxic of nature. Both cultivars experienced limitations from 75 ppb, especially at the 150 ppb SO2 concentration. From these results it appears that PAN 1666 is more adapted to SO2 compared to LS 6164 and levels of 75 ppb SO2 and higher become toxic to these plants. / Thesis (Master of Environmental Sciences)--North-West University, Potchefstroom Campus, 2013

Air pollutant exposure poses a health risk to humans and impacts negatively on agriculture. High levels of air pollution resulted in extensive crop damage and yield reduction in Europe and USA. The Highveld region in South Africa, a very important area for maize and soya production, has already been declared an air pollution hot spot, with SO2 being the most concerning air pollutant. Most of the SO2 over the Highveld originates from the burning of coal for power generation. Developing countries, such as South Africa, are highly dependent on agriculture for food security and high levels of air pollution pose serious risks to the agricultural industry. Currently very little information is available on the effects of air pollution on crop production in South Africa. This study aimed to establish exposure-response relationship for SO2 on soybean and the quantification thereof on the morphological, physiological and biochemical characteristics. Two soybean cultivars were used, namely: LS 6164 and PAN 1666. The plants were fumigated for 7 hours, 7 days a week with 0 (carbon filtered control; CF), 25, 75 and 150 ppb SO2. The effect of SO2 was investigated on the growth, photosynthetic capabilities, photosynthetic gas exchange, peroxidase activity and lipoxygenase activity of the cultivars. Foliar injuries and interveinal chlorosis were visible with increasing levels of SO2 as well as a decrease in biomass accumulation, especially in root biomass; a more prominent feature of LS 6164. The number of nodules of both cultivars decreased insignificantly as the levels of SO2 increased. The number of pods per plant and the average weight of 30 seeds indicated a downward trend with an increase in SO2 concentration. The chlorophyll content of PAN 1666 was lower compared to LS 6164. PAN 1666 had the largest reduction in stomatal conductance at 150 ppb SO2 fumigation. The photosynthetic vitality index indicated that LS 6164 was more sensitive to SO2 inhibition from 25 ppb SO2 and higher, whereas PAN 1666 mostly became sensitive to SO2 from 75 ppb SO2. A decrease in the ability to absorb light energy, the trapping of excitation energy to transfer electrons beyond QA-, and the reduction of end electron acceptors all contributed to the decline in the vitality index. Sulphur content increased significantly in the 75 ppb and 150 ppb treatments of both cultivars. Induced peroxidase and lipoxygenase activity was seen in both cultivars, especially at higher concentrations of SO2 treatments. PAN 1666 had a higher rate of peroxidase and lipoxygenase activity compared to LS 6164. The implication for SO2 on crop production in the highly industrial Highveld area was demonstrated to be potentially of great concern. The dose-response relationships plotted for OJIP parameters emphasized that SO2 is an inhibitor of photosynthesis and phytotoxic of nature. Both cultivars experienced limitations from 75 ppb, especially at the 150 ppb SO2 concentration. From these results it appears that PAN 1666 is more adapted to SO2 compared to LS 6164 and levels of 75 ppb SO2 and higher become toxic to these plants. / Thesis (Master of Environmental Sciences)--North-West University, Potchefstroom Campus, 2013

Made available in DSpace on 2014-08-20T13:44:29Z (GMT). No. of bitstreams: 1 tese_tiago_zanatta_aumonde.pdf: 1079699 bytes, checksum: a746c53d407f8ae1707486f01d299977 (MD5) Previous issue date: 2012-11-19 / Plants can produce compounds with potential for inhibition of germination and initial growth of other plant species. The work was conducted at the Laboratory of Seed Physiology - UFPel in the years 2010 to 2012 and aimed to evaluate the effect of different concentrations of vegetable extracts on the physiology of lettuce and red rice seeds and seedlings. In Articles 1 and 2, we used extracts of leaves of Zantedeschia aethiopica e Philodendron bipinnatifidum at concentrations of 0, 6, 12, 25 and 50%, established from dilution of the 100% concentrated extract in distilled water. Target species as was used lettuce seeds. In the article 3, the red rice was a target species and used the leaves extract of P. bipinnatifidum at concentrations 0; 12; 25; 50 and 75%. Were evaluated the germination, first count germination, germination speed index, length of shoot and primary root, seedling total dry mass, electrical conductivity, chlorophyll content, activity of the enzymes, alfa-amylase, superoxide dismutase (SOD), catalase (CAT) and ascorbarto peroxidase (APX), lipid peroxidation, content of hydrogen peroxide and seedling emergence, length of organs and total dry mass of seedlings emerged. When lettuce seeds and seedlings were exposed to the action of the leaves extract of P. bipinnatifidum, the activity of the enzyme α-amylase changed in seed, first germination and germination test. The increasing of concentration the extract of Z. aethiopica and P. bipinnatifidum provided reduction of seedling emergence, changes in chlorophyll content and activity of the enzymes SOD, CAT, APX and lipid peroxidation in seedlings. The extracts negatively affected the physiological performance of lettuce and red rice seeds. Provided hydrogen peroxide accumulation with increasing concentration, damaging the integrity of cell membranes, contributing to oxidative stress and reducing the incidence of normal seedlings. / As plantas podem produzir compostos com potencial de inibição da germinação e do crescimento inicial de outras espécies vegetais. O trabalho foi realizado no Laboratório de Fisiologia de Sementes - UFPel, nos anos de 2010 a 2012 e objetivou avaliar o efeito de diferentes concentrações de extratos vegetais sobre a fisiologia de sementes e plântulas de alface e arroz-vermelho. Nos artigos 1 e 2, foram utilizados extratos de folhas maduras de Zantedeschia aethiopica e Philodendron bipinnatifidum nas concentrações 0; 6; 12; 25 e 50%, estabelecidas a partir da diluição do extrato 100% concentrado em água destilada. Como espécie alvo utilizou-se sementes de alface. No artigo 3, a espécie alvo foi arroz vermelho e utilizou-se o extrato de folhas maduras de P. bipinnatifidum nas concentrações 0; 12; 25; 50 e 75%. Foram avaliados a germinação, primeira contagem de germinação, índice de velocidade de germinação, comprimento de parte aérea e raiz primária, massa seca total de plântulas, condutividade elétrica, teores de clorofila, atividade das enzimas superóxido-dismutase (SOD), catalase (CAT) e ascorbarto peroxidase (APX), peroxidação de lipídica, peróxido de hidrogênio e emergência de plântulas, comprimento de parte aérea e de raiz e massa seca total das plântulas emergidas. Em sementes e plântulas alface expostas a ação do extrato de folhas de P. bipinnatifidum, a atividade da enzima alfa-amilase foi alterada na semente, nas plântulas da primeira contagem e do teste de germinação. O aumento da concentração do extrato de Z. aethiopica e P. bipinnatifidum reduziu a emergência de plântulas, alterou os teores de clorofila e a atividade da SOD, CAT, APX e incrementou a peroxidação lipídica em plântulas. Os extratos afetaram negativamente o desempenho fisiológico das sementes de alface e arroz vermelho e proporcionaram acúmulo de peróxido de hidrogênio com o aumento da concentração, prejudicando a integridade de membranas celulares, colaborando para o estresse oxidativo e a redução da incidência de plântulas normais.

Made available in DSpace on 2014-08-20T13:44:50Z (GMT). No. of bitstreams: 1 dissertacao_dalcionei_pazzin.pdf: 829971 bytes, checksum: 3d3a9a4e4d6cd6b10887342484141cf8 (MD5) Previous issue date: 2012-01-19 / Soybean cultivation has increased in regions of low lands, traditionally rice-producing areas, these areas being subject to any conditions of soil flooding. Excess water in the soil for the cultivation of soybean can impair the development, production and seed quality. The objective of this study was to evaluate the effect of flooding in lowland soils, at different times of cultivation on morphological, physiological and productivity of soybean varieties, as well as seed quality. We used five soybean cultivars (IAS-5, BRS Macota, CD 221, BRS 255 RR and BMX Apollo RR) under soil flooding conditions a period of five days at different stages, both in the growing season and in the reproductive tract. The experiment was conducted at the Experimental Station of the Lowlands, from Embrapa Clima Temperado headquartered in the Capão do Leão city, RS. Evaluations were made of the seeds in Didactic Laboratory Seed Analysis, of the Universidade Federal de Pelotas (UFPel). During the crop cycle were evaluated: plant height, main stem diameter, chlorophyll content index, and seed production. The characteristics of the seeds were evaluated for physiological quality, seed weight of 1000 and average size. Statistical analysis for the experiments were performed using analysis of variance to assess the significance of main effects and interactions. The comparison test of Tukey was used to average 5% probability. It was found that productivity is adversely affected by flooding the soil, and there are cultivars that have a lower reduction in output. The weight of thousand seeds is lower when plants suffer stress from excess water in the R5 stage, except the cultivar Apollo BMX RR. Flooding caused a reduction in plant height, and decrease in the chlorophyll content in the leaves. The flooding resulted in variation in the soybean crop cycle, and may postpone or advance depending on the maturity date on which it occurred. Flooding causes negative effect on the physiological quality of seeds, varying according to the time of flooding. / O cultivo da soja vem aumentando em regiões de solos de várzea, tradicionalmente áreas produtoras de arroz irrigado, sendo essas áreas sujeitas a eventuais condições de alagamento do solo. O excesso de água no solo durante o cultivo de soja pode prejudicar o desenvolvimento, a produção e a qualidade fisiológica de sementes. O objetivo do trabalho foi avaliar o efeito do alagamento em solo de várzea, em diferentes períodos do cultivo sobre as características morfológicas, fisiológicas e produtividade de cultivares precoces de soja, além da qualidade das sementes produzidas. Foram utilizados cinco cultivares (IAS-5, BRS Macota, CD 221, BRS 255 RR e BMX Apolo RR) de soja sob condição de alagamento do solo um período de cinco dias em diferentes estádios, tanto no período vegetativo quanto no reprodutivo. O experimento foi conduzido na Estação Experimental de Terras Baixas, da Embrapa Clima Temperado sediada no município do Capão do Leão, RS. As avaliações das sementes foram realizadas no Laboratório Didático de Análise de Sementes da Universidade Federal de Pelotas (UFPel). Durante o ciclo da cultura foram avaliados: altura de plantas, diâmetro da haste principal, índice do teor de clorofila (ITC), e produtividade de sementes. As características das sementes foram avaliadas pela qualidade fisiológica, peso de 1000 sementes e tamanho médio. As análises estatísticas para os experimentos foram realizadas através de análise de variância para verificar a significância dos efeitos principais e das interações. O teste de comparação de média utilizado foi Tukey a 5% de probabilidade. Foi constatado que a produtividade é afetada negativamente pelo alagamento do solo, e há cultivares que apresentam menor redução da produção. O peso de mil sementes é inferior quando as plantas sofrem estresse por excesso hídrico no estádio R5, com exceção da cultivar BMX Apolo RR . O alagamento provocou redução na altura de plantas, e diminuição no índice do teor de clorofila (ITC) nas folhas. O alagamento resultou em variação no ciclo da cultura da soja, podendo adiar ou antecipar a maturação dependendo da data em que ele ocorreu. O alagamento causa efeito negativo na qualidade fisiológica das sementes, variando de acordo com a época do encharcamento.