Bio-optical variability of surface waters in Northeastern Gulf of Mexico (NEGOM) was examined using satellite and in situ data. Relatively high chlorophyll-a concentration (chl>=1 mg m-3) and high colored dissolved organic mater (ag443>=0.1 m-1) were generally observed inshore, near major river mouths, and in plumes of Mississippi River water that extended offshore during the three consecutive summer seasons (1998, 1999, and 2000). River discharge dominated chlorophyll-a concentration variability inshore, particularly near major river mouths. Strong interannual variability in chlorophyll-a concentration was observed inshore from Escambia to Tampa Bay region during the winter to spring transition, which was different in 1998 compared to the winter to spring transition in 1999 and 2000. This was related to higher fresh water discharge during the 1997-1998 El Niño-Southern Oscillation event as well as strong upwelling in spring 1998. The Mississippi plume extended >500 km southeast of the Mississippi delta and up to the Florida Keys was observed for the periods extending over 14 weeks between May and September every year of the study. In general, ag443 covaried linearly and inversely with salinity inshore during spring and fall, indicating conservative mixing. The NEGOM salinity-ag443 relationship of fall 1998, i.e., Salinity=36.59-29.86*ag443 (n=8771, r2=0.86; 0.01<=ag443<=0.52, 16 <=S<=36), served as the best predictor of NEGOM salinity based on in situ ag443 observations for spring and fall seasons from all years (<3% mean percentage errors; corresponding to <1.03 psu). This may help estimate salinity from satellite ocean color data, but further testing using data from multiple years is needed to improve such relationship. While river discharge was an important source of colored dissolved organic matter (CDOM), phytoplankton blooms also contributed to CDOM formation in the NEGOM. Using a pigment index of phytoplankton taxonomic groups, the variability in biomass proportion of microphytoplankton explained up to 76% of the variability of the average of normalized phytoplankton absorption coefficients (545, 625, and 673 nm). The clorophyll-specific absorption coefficient, a*ph(440), varies by a factor of 7 (0.02-0.15 m2mg-1). Particle size and pigment composition played important roles in determining a*ph(440) variability. This must be accounted for in chlorophyll-a concentration algorithms based on aph.

Darbo objektas - paprastoji pušis (Pinus sylvestris L.) – Lietuvoje labiausiai paplitusi, jautri užterštam orui medžių rūšis. Paprastosios pušies tyrimai buvo atliekami Lietuvos įmonių AB “Achema” apylinkėse 25 km ruože nuo gamyklos, AB „Akmenės cementas“ 10 km ruože ir AB „Mažeikių nafta“ – 5.4 km ruože nuo gamyklos. Darbo tikslas – Įvertinti paprastosios pušies (Pinus sylvestris L.) spyglių pigmentinės ir antioksidantinės sistemų priklausomybę nuo medynų atstumo iki taršos šaltinio. Darbo metodas. Tyrimai atlikti 14-oje pušyn����������, nutolusių skirtingu atstumu nuo gamyklų: JonA apylinkėse 5 medynai 25 km ruože, šalia AkmC – 4 medynai 10,0 km ruože, šalia MažN – 5 medynai 5,4 km ruože. Šakos, specialiais kirtikliais pjautos 6-8 metrų virš žemės aukštyje. Spygliai buvo atšaldomi ledu ir transportuojami i laboratoriją. Atskirai tiriami pirmamečiai ir antramečiai spygliai. Pigmentų ir askorbo rūgšties koncentracijų nustatymui naudota žalioji spyglių masė. Pigmentams tirti ėminiai buvo ekstrahuojami nedideliu 100 % acetono kiekiu. Spektrofotometru (Genesys 5) išmatuota pigmentų ekstrakto absorbcija 662 nm (chlorofilas a), 644 nm (chlorofilas b), 440,5 nm (karotinoidai) bangos ilgyje. Askorbo rūgštis spygliuose buvo ekstrahuojama su 0.001 N 2,6 dichlorfenolindofenoliu ir titruojama. Darbo rezultatai. Tyrimai AB “Akmenės cementas” transektoje parodė, kad, fotosintezės pigmentų kiekiai reikšmingai mažesni prie gamyklos 0,5 km atstumu augančiose pušyse nei tolimiausiame (10 km... [toliau žr. visą tekstą] / Object of the research – Scots pine (Pinus sylvestris L.) – common tree in Lithuania, sensitive to air pollution. Research of Scots pine were conducted in the industrial areas of Lithuania companies JSC – (25 km transect) near the factory JSC (10 km sector) and an oil refinery (in 2 – 5,4 km distance). Goal of the research – to evaluate quality of photosynthetic pigments and ascorbic acid in the needles of Scots pine growing around main sources of industrial pollution. Methodology of the research. Research was performed in 17 pine forests, at different distance from the factories. In the surroundings of the nitrogen fertilizer factory 8 forests were examined in 25 km distance, near the cement factory – 4 forests in 10 km distance and near the oil refinery – 5 forests in 5.4 km distance. In each site, samples of current-year and 1-year-old needles were taken from 4 pines at the height of 6-8 m aboveground. The needles were cooled and transported to laboratory. Concentrations of the pigments and ascorbic acid were determined in the fresh needle material. The needles were grinded and in 20ml of 100% acetone. The absorbance at 662 nm (chlorophyll a), 644 nm (chlorophyll b) and 440.5 nm (carotenoids) was measured by spectrophotometer (Genesys 5, US). The ascorbic acid from the needles was extracted with 0.001 N 2.6-dichlorophenolindophenol and estimated titrimetrically. Results of the research. Research results showed that number of photosynthesis pigments is meaningly... [to full text]

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: 40-41)

Orientador: Rogério Peres Soratto / Banca: Roberto Lyra Villas Boas / Banca: Marcelo Andreotti / Resumo: Técnicas de manejo que possibilitem a maximização de absorção de N pelo feijoeiro são de extrema importância, em razão do alto custo dos fertilizantes nitrogenados e das perdas de N, que podem representar prejuízos aos produtores e riscos ao ambiente. Nesse sentido, a estimativa da necessidade de N pelo feijoeiro mediante a leitura indireta de clorofila, pelo clorofilômetro portátil, pode ser uma alternativa viável. Contudo, ainda existe a necessidade de estabelecimento de critérios para a utilização desse aparelho na cultura do feijão. Os objetivos do presente trabalho foram: a) verificar a correlação entre o índice relativo de clorofila (IRC), obtido mediante leituras do clorofilômetro portátil (SPAD- 502), e o teor de N da folha de dois cultivares de feijão (IAC Alvorada e Pérola) em diversos estádios de desenvolvimento; b) verificar o comportamento do IRC e do índice de suficiência de N (ISN) em função dos manejos de N aplicado em cobertura; c) avaliar o ISN calculado com base nas medidas IRC nas folhas como indicador do momento de aplicação de N em cobertura na cultura do feijão e, d) verificar qual valor do ISN (90% e 95%) em relação ao tratamento referência é o mais adequado para indicar o momento da adubação nitrogenada em cada cultivar utilizado. O trabalho foi constituído de um experimento conduzido durantes as safras "das águas" e "da seca" do ano agrícola 2009/2010, na Fazenda Experimental Lageado da FCA/UNESP - Botucatu-SP. O delineamento experimental foi em blocos ao acaso, em esquema de parcela subdividias, com quatro repetições. As parcelas foram constituídas por dois cultivares de feijão (Pérola e IAC Alvorada) e as subparcelas por seis manejos do N M1: 40 kg ha-1 de N na semeadura + 80 kg ha-1 de N aos 15 dias após a emergência (DAE) + 80 kg ha-1 de N aos 30 DAE; M2: 20 kg ha-1 de N na semeadura... (Complete abstract click electronic access below) / Abstract: Management techniques that allow the maximization of N uptake by bean crop are extremely important, because of high cost of nitrogen fertilizers and N losing, which may represent losses to producers and risks to the environment. In this sense, the estimation of N needs of common bean crop by indirect reading of chlorophyll can be a viable alternative. However, there is remains the need to establish criteria for using this device in the bean. The aims of this study were: a) determine the correlation between relative chlorophyll index (RCI), obtained by reading of chlorophyll (SPAD 502) and leaf N content of two bean cultivars (IAC Alvorada and Pérola) in various stages of development; b) verify the behavior of the RCI and N sufficiency index (NSI) for different sidedressing N management practices; c) evaluated the NSI calculated based on the measures RCI leaves as an indicator of time of N application in sidedressing on bean crop and d) verify that value of NSI (90% and 95%) compared to the reference treatment is most appropriate to indicate the moment of fertilization in each cultivar. The work was composed of an experiment conducted in "rainy" and "dry" season of agricultural year 2009/2010 at the Experimental Lageado Farm FCA/UNESP - Botucatu-SP. A randomized block in split plot scheme, with four replications was used. Plots consisted of two bean cultivars (IAC Alvorada and Pérola) and subplots of six N managements M1: 40 kg ha-1 N at sowing + 80 kg ha-1 at 15 days after emergence (DAE) + 80 kg ha-1 N at 30 DAE; M2: 20 kg ha-1 N at sowing + 40 kg ha-1 N at 15 DAE + 40 kg ha-1 N at 30 DAE; M3: 10 kg ha-1 N at sowing + 20 kg ha-1 N at 15 DAE + 20 kg ha-1 N at 30 DAE; M4: 20 kg ha-1 N at sowing + 30 kg ha-1 N when chlorophyll meter readings indicated NSI <95%; M5: 20 kg ha-1 N at sowing + 30 kg N ha-1 N when chlorophyll meter readings indicated NSI <90% and, M6: control (without nitrogen)... (Complete abstract click electronic access below) / Mestre

Purpose of this research was to investigate physiological differences between monocots (Digitaria horizontalis) and dicots (Emilia coccinea) in function on the application of the mixture of herbicides clomazone + ametryn and its relation with mortality of these species. For this, conducted two experiments, one for each species, where was applied the herbicide mixture in four doses: 0 (water); 2.5 L. ha-1 (0.5 kg a.i ha-1 of clomazone + 0.75 kg a.i.ha-1 of ametrina) ; 5 L. ha-1 ( 1 kg a.i ha-1 of clomazone + 1.5 kg a.i ha-1 of ametrina) e 10 L. ha- 1 (2 kg a.i ha-1 of clomazone + 3 kg a.i ha-1 of ametrina), when the plants were 30 days after sowing. Physiological variables studied were levels of photosynthetic pigments, chlorophyll fluorescence emission, superoxide dismutase (SOD) activity, ascorbate peroxidase (APX) activity, electrolyte leakage and lipid peroxidation 72 hours after the apliccation. After 25 days of the application were counted the frequency of dead plants and dry matter accumulation per plant. The data were submitted to analysis of variance and exponential or linear regression analysis. The total chlorophyll and carotenoids decreased exponentially with increasing doses of the mixture in the two species studied. The values of maximum fluorescence (Fm), maximum quantum yield (Fv/Fm) and effective quantum yield (YIELD) also decreased exponentially for both species, since the minimal fluorescence (Fo) decreased linearly for both. The SOD activity decreased linearly in both species, but this decrease was more pronounced in monocots. The APX showed no significant change in its activity. The dicots showed a linear increase more pronounced in electrolyte leakage compared with the monocot. For lipid peroxidation, the species were similar to those electrolyte leakage. In relation to plant mortality, the dose of 10 L.ha-1 eliminated only 53.84% of the population of D. horizontalis while the same dose for E. coccinea eliminated 100% of the population. Given the observations, concluded that the species that suffered the greatest damage of the cell membrane was obtained more reduction in dry matter per plant and a higher percentage of mortality. And other mechanisms than those evaluated in this study may be related to increased tolerance of D. horizontalis to mixture of ametryn+clomazone. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo da pesquisa foi verificar diferenças fisiológicas entre mono (Digitaria horizontalis) e dicotiledôneas (Emilia coccinea) em função da aplicação da mistura de herbicidas clomazone+ametrina e sua relação com a mortalidade dessas espécies. Para isso, foram realizados dois experimentos, um para cada espécie, onde aplicou-se a mistura de herbicidas clomazone e ametrina, em quatro doses: 0 (água); 2,5 L. ha-1 (0,5 kg i.a ha-1 de clomazone + 0,75 kg i.a.ha-1 de ametrina) ; 5 L. ha-1 ( 1 kg i.a ha-1 de clomazone + 1,5 kg i.a ha-1 de ametrina) e 10 L. ha-1 (2 kg i.a ha-1 de clomazone + 3 kg i.a ha-1 de ametrina), aos 30 dias após a semeadura. As variáveis fisiológicas estudadas foram: teores de pigmentos fotossintéticos, emissão da fluorescência da clorofila a, proteínas solúveis, atividade da superóxido dismutase (SOD), atividade da ascorbato peroxidase (APX), extravasamento de eletrólitos e peroxidação de lipídeos 72 horas após a aplicação. Após 25 dias da aplicação foi contabilizada a frequência de plantas mortas e a matéria seca acumulada por planta. Os dados foram submetidos à análise de variância e análise de regressão exponencial ou linear. Os teores clorofila totais e carotenóides decresceram exponencialmente com o aumento das doses da mistura de herbicidas, nas duas espécies estudas. Os valores do rendimento quântico potencial (Fv/Fm), rendimento quântico efetivo (YIELD) e fluorescência máxima (Fm) também decresceram exponencialmente para as duas espécies, já a fluorescência inicial (Fo) decresceu linearmente para ambas. A atividade da SOD decresceu linearmente em ambas as espécies, porém esse decréscimo foi mais acentuado na monocotiledônea. Não houve alteração significativa da atividade da APX. A dicotiledônea apresentou aumento linear mais acentuado no extravasamento de eletrólitos comparado com a monocotiledônea. Para a peroxidação de lipídios, as espécies apresentaram comportamento semelhante aos de extravasamento de eletrólitos. Em relação à mortalidade das plantas, a dose de 10 L.ha-1 eliminou apenas 53,84% da população de D. horizontalis enquanto a mesma dose eliminou 100% da população de E. coccinea. Diante das observações, conclui-se que a espécie que sofreu maior dano de membranas celulares foi a que obteve maior redução na meteria seca por planta e maior percentual de mortalidade. Outros mecanismos que não os avaliados nessa pesquisa podem estar relacionados com a maior tolerância de D. horizontalis à mistura de ametrina+clomazone.

Baby spinach is a relatively new crop in South Africa with both commercial significance and reputed health benefits. It is known to assist in combating degenerative conditions associated with ageing, such as heart disease, cardiovascular disease, Alzheimer’s disease, cataracts and several forms of cancer. Three parallel NPK trials were conducted to investigate the effects of nitrogen (N), phosphorus (P) and potassium (K) on the growth and development of baby spinach. N and P treatments were arranged as (0, 45, 75, 105, 120 kg.ha -1 N and P), and K treatments were arranged as (0, 63, 85, 127, 148 kg.ha -1) in a randomised complete block designed with four replicates. Results showed that yield, dry matter, chlorophyll content and Leaf Area Index (LAI) were significantly increased by increasing the N application, while K had a significant effect on the LAI but not on yield, dry matter, chlorophyll content or stomatal conductance. Nitrogen treatments quadrupled fresh yield, dry matter and chlorophyll content, reaching maximum impact at 75 kg.ha-1 N. Phosphorus application showed significantly increased yields, dry matter and chlorophyll content, reaching maximum impact at 75 kg.ha-1 P. Therefore, to achieve optimum growth with N and P, 75 kg.ha-1 is recommended. The optimum rates of N, P and K were then used to formulate a NPK combined trial which was arranged as 0, 30:30:40, 45:45:60, 60:60:70, 75:75:90 kg.ha-1 in a randomised complete block design with three replicates. The results showed that maximum impact on yield, chlorophyll content, fresh and dry matter was achieved when combined NPK was applied at 45:45:60 / Agriculture and  Animal Health / M. Sc. (Agriculture)

An analysis of algal biomass measured by chlorophyll-a concentration in Lake Texoma was performed as a part of a monitoring program to develop baseline environmental data in order to detect the potential effects of engineered changes in chloride concentrations in the reservoir. This portion of the research project focused on two main research objectives. The first objective was evaluating the effect of sampling strategy on the ability to adequately reflect standing crop estimates and trends in algal biomass. Two sampling regimes utilizing replication of three versus ten samples were applied and then analyzed using a minimum detectable difference algorithm to determine the necessary magnitude of replication to represent the variation in the metric. Chlorophyll-a distribution was analyzed for zonation patterns expected in a river-run reservoir to establish the importance of representative sampling of river, transition and main lake zones of the reservoir for management decisions and trophic characterization.

Indiana University-Purdue University Indianapolis (IUPUI) / Cyanobacterial blooms are currently one of the most important issues faced by environmental agencies, water authorities and public health organizations. Remote sensing provides an advanced approach to monitor cyanobacteria by detecting and quantifying chlorophyll-a (Chl-a) and phycocaynin (PC). In this thesis, an analytical bio-optical model, more typically applied to ocean waters, was modified to accommodate the complexity of inland waters. The newly developed models work well to estimate inherent optical properties, including absorption and backscattering coefficients, in eight different study sites distributed around the globe. Based on derived absorption coefficients, Chl-a and PC concentrations were accurately retrieved for data sets collected annually from 2006 to 2010, and the estimation accuracy exceeded that of currently used algorithms. An important advantage of the model is that low concentrations of Chl-a and PC can be predicted more accurately, enabling early warning of cyanobacterial blooms. In addition, the results also indicated good spatial and temporal transferability of the algorithms, since no specific calibration procedures were required for data sets collected in a different sites and seasons. The compatibility of the newly developed algorithm with MERIS spectra provides the possibility for routine surveillance of cyanobacterial growth in inland waters.

Antarctic krill (Euphausia superba) is a key species of the Southern Ocean, impacted by climate change and human exploitation. Understanding how these changes affect the distribution and abundance of krill is crucial for generating projections of change for Southern Ocean ecosystems. Krill growth is an important indicator of habitat suitability and a series of models have been developed and used to examine krill growth potential at different spatial and temporal scales. The available models have been developed using a range of empirical and mechanistic approaches, providing alternative perspectives and comparative analyses of the key processes influencing krill growth. Here we undertake an intercomparison of a suite of the available models to understand their sensitivities to major driving variables. This illustrates that the results are strongly determined by the model structure and technical characteristics, and the data on which they were developed and validated. Our results emphasize the importance of assessing the constraints and requirements of individual krill growth models to ensure their appropriate application. The study also demonstrates the value of the development of alternative modelling approaches to identify key processes affecting the dynamics of krill. Of critical importance for modelling the growth of krill is appropriately assessing and accounting for differences in estimates of food availability resulting from alternative methods of observation. We suggest that an intercomparison approach is particularly valuable in the development and application of models for the assessment of krill growth potential at circumpolar scales and for future projections. As another result of the intercomparison, the implementations of the models used in this study are now publicly available for future use and analyses.

Master of Science / Department of Agronomy / P. V. Vara Prasad / Grain sorghum (Sorghum bicolor L. Moench) is the fourth most important cereal crop grown throughout the semi-arid regions of the world. It is a staple food crop in Africa and Asia, while it is an important feed crop in the United States (US). More recently it is increasingly becoming important as a potential bioenergy feedstock crop around the world. The state of Kansas is the largest producer of grain sorghum in the US and contributes 40% of the total production. Drought is one of the major environmental factors limiting sorghum production in the semi-arid regions of the US, Asia and Africa. It is estimated that global crop losses due to drought stress exceed $10 billion annually. In crop production, drought stress can be classified into pre- or post-flowering. Even though the world collections of sorghum contain over 35,000 accessions, the genetic base currently used in breeding programs is very small (about 3%). Thus, it is important to identify diverse breeding lines for crop improvement. The diversity (association) panel consisting of 300 sorghum lines from all over the world was assembled for trait evaluation and association mapping. In this research these lines were grouped into the five major races (Figure 1) and 10 intermediate races of sorghum. The objectives of the research are to: (i) quantify the performance of the diversity panel under field conditions in Kansas, (ii) identify critical physiological traits affected by drought at both pre- and post-flowering stages of sorghum development, (iii) identify the most sensitive stage to drought stress during the reproductive phase of sorghum development and, (iv) test the feasibility of using a chlorophyll fluorescence assay (CVA) as a tool for identifying stay-green lines in grain sorghum during early stages of crop development. Field experiments were conducted in 2006 and 2007 in two locations in Kansas (Manhattan and Hays) under rain fed and irrigated conditions for the association panel. Objectives (iii) and (iv) were achieved with controlled environment experiments conducted in the greenhouse at the agronomy department, Kansas State University in 2006 and 2007. Results showed that there was large genetic variability among and within different races in the diversity panel for growth, physiological traits and yield components. Some genotypes showed yield stability across the different environments that were investigated. Drought significantly decreased seed number and harvest index across genotypes and races. In grain sorghum the period prior to flowering (panicle initiation) was the most sensitive stage to drought stress, in terms of its effect on seed-set, during reproductive development. A cell viability assay showed that there were significant differences in the loss of cell viability between leaf sample of stay green and non-stay green genotypes when leaf samples are collected in the morning and subjected to high respiratory demand. Therefore the chlorophyll fluorescence assay has potential as a tool for stay green trait screening at early stages of growth in grain sorghum.