The objective of this study was to determine the effect of increasing leaf area index on the photosynthetic temperature response of a wheat canopy. Hard red spring wheat (Triticum aestivum L. cv. Veery-10) was grown hydroponically in a growth chamber, which also served as the gas-exchange chamber. Gas-exchange parameters were measured on single leaves and on wheat canopies at various leaf area indices. The temperature response curves of the canopy shifted from being steeper with a high temperature optimum to being flatter with a lower temperature optimum as leaf area index increased from 0 to 20.0 m2m-2. Single-leaf and canopy measurements show that this shift was primarily a result of increasing respiration from accumulating stems and reproductive structures and, to a lesser extent, from lower temperature optimums associated with lower light levels within the canopy.

The marine cyanobacterium Synechococcus WH7803 adapts to changes in light intensity by changing its photosynthetic physiology. This work is a study o f the rate o f photoadaptation of Synechococcus WH7803 in laboratory cultures. Cultures were shifted from constant 8 µEm-2s-1 light to constant 80 µEm-2s-1 light, from constant 80 µEm-2s-1 light to 8 µEm-2s-1 light and from different light regimes to a single fluctuating light regime. The response of high iron cultures grown in modified aquil culture medium at 5*10-6M Fe was compared with the response of low iron cultures grown in modified aquil medium at 1*10-6M Fe. Cultures were assayed every 2 days for at least 10 days, assaying cell population density by fluorescence microscopy, chlorophyll a by spectrophotometry of acetone extracts, total protein by the bicinchoninic acid method, and photosynthesis vs. irradiance (P vs. I) response by H14CO3 uptake at 10 light intensities. Iron nutrition did not strongly affect the rate of photoadaptation as determined from the slopes of P vs. I curves as light approaches zero (the parameter called alpha). The rate of chlorophyll a synthesis was the parameter most strongly affected by iron nutrition, slowing in restricted iron medium. Based on alpha per cell, the adaptation time to the shift from constant 8 µEm-2s -1 light to constant 80 µEm-2s -1 light was less than 2 days. Based on other culture parameters the time to complete adaptation may be closer to 8 days. Based on alpha per cell, the adaptation time to the shift from constant 80 µEm-2s -1 light to constant 8 µEm-2s -1 light was on the order of 2 days. Based on other culture parameters the time to complete adaptation may exceed 10 days.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20337号 / 工博第4274号 / 新制||工||1662(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 梶 弘典, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Ozone is known to be the most widespread phytotoxic air pollutant. Ozone causes visible injury, reductions in photosynthesis, growth, and yield. Plant response to ozone may vary with species, varieties, and physiological age. Comparison between sensitive and tolerant cultivars has a key role in assessing ozone damage, investigating the sites of cellular injury, and identifying ozone tolerance mechanism. The objectives of this study were to investigate the effects of high ozone concentration (200 ppb) as well as ambient ozone concentrations (under field conditions) on net CO2 assimilation and PSII function in plants with different sensitivities to ozone. Two species of plants, tobacco (Nicotiana tabacum L.) and black cherry (Prunus serotina) were studied. Gas exchange analysis and chlorophyll fluorometry were utilized to characterize physiological function. Two tobacco cultivars, Bel-B and Bel-W3, tolerant and sensitive to ozone, respectively, were grown in a greenhouse supplied with charcoal filtered air and then exposed to 200 ppb ozone for 4hr. Effects on chlorophyll fluorescence, net photosynthesis, and stomatal conductance are described. Quantum yield was calculated from chlorophyll fluorescence and the initial slope of the assimilation-light curve measured by the gas exchange method. Only the sensitive cultivar, Bel-W3, developed visible injury symptoms involving up to 50% of the 5th leaf. The maximum net photosynthetic rate of ozone-treated plants of the tolerant cultivar was reduced 40% compared to control plants immediately after ozone fumigation; however, photosynthesis recovered by 24 hr post fumigation and remained at the same level as control plants. In the sensitive cultivar, on the other hand, ozone exposure reduced maximum net photosynthesis up to 50%, with no recovery, apparently causing permanent damage to the photosystem. Reductions in apparent quantum efficiency, calculated from the assimilation-light curve, differed between cultivars. Bel-B showed an immediate depression of 14% compared to controls, whereas Bel-W3 showed a 27% decline. Electron transport rate (ETR), at saturating light intensity, decreased 58% and 80% immediately after ozone treatment in Bel-B and Bel-W3, respectively. Quantum yield decreased 28% and 36% in Bel-B and Bel-W3, respectively. It can be concluded that ozone caused a greater relative decrease in linear electron transport than maximum net photosynthesis, suggesting greater damage to PSII than the carbon reduction cycle. Two different sensitivity classes of black cherry, tolerant and sensitive, growing under natural environmental conditions in Giles County, VA were assessed for physiological responses to ambient ozone concentrations. Additional measurements were made at two other sites near Blacksburg. Leaf gas exchange rates and visible foliar injury were determined monthly during the growing seasons of 2000, 2001, and 2002 to characterize the relationship of injury to altered photosynthetic function. Ambient ozone levels were sufficient to induce visible symptoms which were highly correlated with a reduction in PnMAX (maximum net photosynthetic rate under saturating light conditions) and à CO2 (quantum yield for carbon reduction) only in sensitive black cherry. Electron transport rate (ETR) and quantum yield of PSII (à PSII) were also reduced in sensitive black cherry. Maximum photochemical efficiency (Fv/Fm) in sensitive trees was severely damaged by ambient ozone. There were positive correlations between increasing cumulative ozone concentration and substantial reductions in PnMAX and in à CO2 of sensitive trees compared to tolerant trees. There was a negative correlation between chlorophyll content and percent leaf injury in sensitive black cherry / Ph. D.

Made available in DSpace on 2017-07-10T17:37:00Z (GMT). No. of bitstreams: 1 Thaisa_Muriel_Mioranza.pdf: 2175568 bytes, checksum: 5bdfcf6dcf5708e0c3a818711f1c959a (MD5) Previous issue date: 2015-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work was to study the influence of homeopathic or high diluted solution of Thuya occidentalis in the control of root-knot nematode Meloidogyne incognita in tomato plants and physiological responses promoted in the plant. The experiment consisted of in vitro and in vivo assay. The treatments were different dynamization of T. occidentalis 6, 12, 24, 50, 100, 200 and 400CH (centesimal hahnemaniana dilution) and the water (control). In the in vitro experiment nematodes were treated with 0.1% homeopathic solution of the treatments for 24 hours for the motility test and 15 days for hatching test. For the in vivo test, the experiment was carried out in two years, the first year in completely randomized design and the second year in a randomized block design, both with eight treatments and with four replications. At the moment that the tomato seedlings were transplanted, they were submerged in a 0.1% solution of treatments. Subsequently were inoculated 4188 eggs and 661 second-stage juveniles (J2) in the first experiment and 4350 eggs and 700 J2 in the second experiment. Were performed weekly sprays of 0.1% solution of the treatments in the shoots of plants. The plants were cultivated until the nematodes complete a development cycle. We evaluated the number of galls, egg masses, number of eggs and J2 in the roots, number of eggs and J2 in the soil, plant height, shoot fresh and dry weight, root volume, number of clusters, number of fruits per bunch, fresh and dry fruit weight and relative chlorophyll content. In the 2014 experiment were chosen the dynamizations 6, 24 and 50CH, and the control with nematode and treated with water and plants without nematodes and without treatment, with four repetitions each for the measurement of photosynthesis rates (A), stomatal conductance (gs), transpiration (E), internal CO2 concentration on leaf (Ci) and leaf temperature (Tleaf) varying the photosynthetic photon flux density (PPFD). It was also calculated the efficiency of water use (USA) (A/E), intrinsic water use efficiency (EUIA) (A/gs) and the instantaneous efficiency of carboxylation (A/C). The treatments did not show nematostatic and nematicide effect even did not influence in hatches eggs for in vitro assay. To the in vivo assay, in 2013, T. occidentalis 100CH caused a reduction in the population of J2 in the roots, as well as 200CH promoted an increase in the volume root and fruit fresh weight of the first bunch. In 2014, 100CH caused a decrease in the number of egg masses and J2 in the soil, and influenced the development of the root, while 50CH increased the fresh weight of shoots of tomato plants. The specific measures of gas exchange did not differ between treatments. Plants infected with M. incognita and without treatment caused an increase in the net photosynthesis and the carboxylation capacity for response curve to light. Already T. occidentalis 24CH inhibited the effect of increased CO2 fixation in tomato plants inoculated with M. incognita, providing similar behavior to healthy plants in different densities of photons. Plants of homeopathic treatments showed higher leaf temperature. T. occidentalis showed control capability of root-knot nematode and influenced in tomato growth and physiology / O objetivo desse trabalho foi estudar a influência de soluções ultradiluídas de Thuya occidentalis no controle do nematoide de galhas Meloidogyne incognita em plantas de tomateiro e as respostas fisiológicas promovidas na planta. O experimento foi constituído de ensaios in vitro e in vivo. Os tratamentos utilizados foram diferentes dinamizações de T. occidentalis 6, 12, 24, 50, 100, 200 e 400CH (centesimal hahnemanniana) e a testemunha água (controle). No experimento in vitro os nematoides ficaram em contato direto com a solução de 0,1% dos tratamentos, por 24 horas para o teste de motilidade e 15 dias para o teste de eclosão. Para o teste in vivo, o experimento foi realizado em dois anos, sendo o primeiro ano em delineamento inteiramente casualizado e o segundo ano em delineamento de blocos ao acaso, ambos com oito tratamentos e quatro repetições. No momento em que as mudas de tomateiro foram transplantadas, estas foram submersas em uma solução de 0,1% dos tratamentos. Posteriormente foram inoculados 4188 ovos e 661 juvenis de segundo estágio (J2) no primeiro experimento e 4350 ovos e 700 J2 no segundo experimento. Foram realizados pulverizações semanais da solução de 0,1% dos tratamentos na parte aérea das plantas. As plantas foram conduzidas até que os nematoides completassem um ciclo de desenvolvimento. Foram avaliados o número de galhas, massas de ovos, número de ovos e J2 nas raízes, número de ovos e J2 no solo, altura de plantas, massa fresca e seca da parte aérea, volume de raiz, número de cachos, número de frutos por cacho, massa fresca e seca dos frutos e teor relativo de clorofila. No experimento de 2014, foram escolhidas as dinamizações de 6, 24 e 50CH, além da testemunha com nematoide e tratada com água e testemunha sem nematoide e sem tratamento, com quatro repetições cada, para a mensuração da taxa de assimilação líquida de CO2 (A), transpiração foliar (E), condutância estomática (gs), concentração interna de CO2 (Ci) e temperatura foliar (°C), variando-se a densidade de fluxo de fótons fotossinteticamente ativos (DFFFA). Também foi calculada a eficiência no uso da água (EUA) (relação A/E), eficiência intrínseca no uso da água (EUIA) (relação A/gs) e a eficiência instantânea da carboxilação (A/Ci) (relação A/Ci). Os tratamentos não mostraram efeito nematostático e nematicida assim como não influenciaram na eclosão de ovos para o ensaio in vitro. Já para o in vivo, em 2013, T. occidentalis 100CH causou redução na população de J2 nas raízes, assim como 200CH promoveu aumento no volume de raiz e massa fresca de frutos do primeiro cacho. Em 2014, 100CH promoveu diminuição no número de massas de ovos e J2 no solo, e influenciou no desenvolvimento da raiz, enquanto 50CH incrementou a massa fresca da parte aérea de tomateiro. As medidas pontuais de trocas gasosas não apresentaram diferença entre os tratamentos. Plantas infectadas com M. incognita e sem tratamento promoveram aumento na fotossíntese líquida e capacidade de carboxilação pela curva de resposta à luz. Já T. occidentalis 24CH inibiu o efeito de maior fixação de CO2 em tomateiros inoculados por M. incognita, proporcionando comportamento semelhante às plantas sadias em diferentes densidades de fótons. Plantas submetidas aos tratamentos homeopáticos apresentaram maior temperatura foliar. T. occidentalis apresentou capacidade de controle de nematoide de galhas e influenciou no crescimento e fisiologia do tomateiro

While animal steroid hormones are very well known and have been studied for a long time, in plants no steroid substances were known until relatively recently. Only in the second half of the past century brassinosteroids were discovered; later on, their hormonal function in plants was confirmed. Still a lot of unknown remains as regards their function in plant cells. This paper presents in its first part the evidence that brassinosteroids control in maize (Zea mays L.) grown under field conditions not only its morphology and yield but also some developmental/reproduction characteristics like e.g. number of female inflorescences or speed of the development of male inflorescences. Particular response of a plant depends, however, on the type of applied brassinosteroid, its concentration, and last but not least also on a particular maize genotype and developmental stage of the plant during applicatin. Impact of brassinosteroids on primary photosynthetic processes in plants has not been proven under these conditions, neither on the activity of photosystem (PS) I nor on the Hill reaction. No statistically significant differences in the content of photosynthetic pigments have been found either. Another topic dealt with in this thesis is the possible protective influence of brassinosteroids on plants...

Master of Science / Department of Biology / David C. Hartnett / Perennial grasses on tallgrass prairie primarily reproduce vegetatively via the belowground bud bank, yet the production, dynamics, and morphology of belowground buds is largely unexplored. Since the two main photosynthetic pathway guilds (C3 and C4) on tallgrass prairie vary in their aboveground phenology, their belowground phenology would also be expected to vary. Differences in bud production, development, and spatial arrangement result in different growth forms. Therefore, an extensive biweekly examination of a dominant tallgrass prairie C4 rhizomatous grass Andropogon gerardii and C3 caespitose grass Dichanthelium oligosanthes was conducted over an entire year. Andropogon gerardii and D. oligosanthes have multiple distinctive bud developmental stages. Andropogon gerardii was synchronous in its bud development and its bud bank was composed of multiple annual cohorts. The bud bank of D. oligosanthes was developmentally asynchronous and was comprised of a single bud cohort since its bud bank underwent a complete turnover in early summer. The different roles of buds in the life history of each species reflected their differences in bud longevity, quality, and dormancy. In D. oligosanthes, belowground buds enabled plant survival over the C3 summer dormant period whereas juvenile tillers overwintered during the longer winter dormant period. In contrast, A. gerardii survived its single, winter dormant period as dormant buds. The higher-order bud production observed in D. oligosanthes multiplied its tiller production potential and, along with its shortened internodes, contributed to its caespitose growth form. The rhizomatous growth form of A. gerardii resulted from its lack of higher-order bud production and its elongated internodes. Differences in production of buds per vegetative and flowering tiller were quantified in A. gerardii. Flowering tillers of A. gerardii produced larger numbers of buds per tiller and transitioned a larger proportion of their buds to tillers than did vegetative tillers. Therefore, no tradeoff between sexual and vegetative reproduction was evident. Developmental constraints likely prevented such a tradeoff. Bud bank dynamics offer insight into the control of grass population dynamics, production, and ultimately aboveground net primary production (ANPP) and will be useful in understanding the underlying mechanisms by which management practices and environmental change can alter perennial grasslands.

Tyrimai, siekiant išsiaiškinti, kaip keičiasi fotosintetinių rodiklių intensyvumas ir grūdų kokybė bei derlingumas priklausomai nuo augimo tarpsnio bei tręšimo azotinėmis trąšomis, atlikti 2009-2010 metais. Pigmentų ir tirpiųjų sacharidų kiekis tirtas Agrobiotechnologijos laboratorijoje, o grūdų kokybės rodikliai ištirti AB „Kauno grūdai“ laboratorijoje. Žieminiai kviečiai auginti Lietuvos žemės ūkio universiteto Bandymų stotyje, kur dirvožemis IDg8-k (LVg-p-w-cc) – karbonatingas sekliai glėjiškas išplautžemis (Calc(ar)i-Epihypogleyic Luvisols). Tyrimamas pasirinktos dvi žieminių kviečių veislės: labai gerų kepimo savybių ’Ada’ ir gerų kepimo savybių ’Tauras DS’. Buvo tiriama, kaip vegetacijos metu kinta pigmentų ir sacharidų kiekis augalų lapuose ir kaip azoto trąšos įtakojo baltymų, šlapiojo glitimo, sedimentacijos, krakmolo, kritimo skaičiaus pokyčius grūduose ir grūdų derlingumą. Azoto trąšos augaluose skatino bendrą pigmentų kiekio didėjimą, o tirpiųjų sacharidų kaupimuisi esminės įtakos neturėjo. Taip pat azoto trąšos beveik visuose variantuose patikimai skatino baltymų kaupimąsi grūduose, didino sedimentaciją ir šlapiojo glitimo kiekį, o krakmolo kiekis mažėjo atvirkščiai proporcingai baltymų kiekiui. Tręšimas azoto trąšomis visuose variantuose patikimai didino derlingumą. / The research was carried out in the period from 2009 to 2010 to determine the changes in the intensity of photosynthetic characteristics ,grain quality and yield, depending on the growth phase and fertilization with nitrogen fertilizer. The amount of pigments and soluble sugars was investigatd in the laboratory of Agrobiotechnology and the indicators of grain quality were explored in the laboratory of JSC „Kauno grūdai“. Winter wheat were grown in the Experimental Station of Lithuanian University of Agriculture, where the soil is IDg8 k (LVD-pw-cc) - calcareous shallow Luvisols (Calc (or) i Epihypogleyic Luvisols). Two varieties of winter wheat were selected for the experimental study: ’Ada’ with a very good baking properties and ’Tauras DS’ with good baking properties. The research focused on how vegetation changes affect the pigment and sugars content in the plant leaves, as well as the influence of nitrogen fertilizers on the grain yield and changes in content of protein, wet gluten, sedimentation and starch in the investigated grain. The results suggest that the nitrogenous fertilizers stimulated the overall growth of the cultivar, the pigment content but it had no significant effect on the accumulation of soluble sugars .Moreover, almost in all cases of the nitrogen fertilizer treatments it significantly promoted the accumulation of grain protein, increased sedimentation and wet gluten content however the starch content decreased inversely with the protein. The grain... [to full text]

I quantified seasonal variations in corticular photosynthesis in 1st through 5th order branches of Myrica cerifera L. (Myricaceae) in order to determine whether corticular photosynthesis contributes to whole plant carbon gain by reducing respirational CO2 loss. Maximum % refixation was 110 ± 39 % of CO2 efflux in the dark (Rd) in 1st order branches during winter, minimum was 18 ± 3 % in 5th order branches during summer. Variations in % refixation paralleled changes in photosynthetically active radiation (PAR). As light attenuated with increasing branch order % refixation decreased. Increased PAR in the winter due to a more sparse canopy lead to increases in % refixation. Total chlorophyll content and chlorophyll a:b ratios were consistent with shade acclimation as branch order increased. Corticular photosynthesis may be a mechanism to enhance shrub expansion due to increased whole plant carbon use efficiency (CUE) and water use efficiency (WUE) attributed to refixation.