O objetivo do estudo foi a avaliação dos mecanismos termorreguladores, baseada numa abordagem temporal em função de diferentes armazenamentos de calor, proporcionados por diferentes tipos de ambientes térmicos (com e sem radiação solar). Foram utilizadas 12 búfalas da raça Mediterrânea que foram submetidas a quatro experimentos durante o verão de 2010 a 2012 delineados para o comprimento dos objetivos específicos. Nos vários experimentos os parâmetros meteorológicos registrados foram: temperatura de bulbo seco, temperatura de bulbo úmido, umidade relativa do ar, velocidade do vento e temperatura de globo negro. Os parâmetros fisiológicos avaliados foram: temperatura retal, temperatura da base da cauda, temperatura da epiderme, temperatura de superfície do pelame, frequência respiratória e taxa de sudação. As análises estatísticas foram realizadas com auxílio do programa Statistical Analysis System, versão 9.1.3 (SAS Institute Inc., Cary, NC, USA), utilizando-se os procedimentos PROC MIXED. No experimento 1 que visou verificar as reações termorreguladoras ao ambiente aquecido em unidade biometeorológica, o aumento da temperatura do ar em ambiente controlado influenciou todas as variáveis fisiológicas ao longo do dia (P<0,01). O incremento na taxa de sudação durante o período de estresse térmico determinou a depleção na concentração plasmática de potássio (P=0,0051). No experimento 2que avaliou as reações termorreguladoras na presença de radiação solar direta averiguamos que houve influência da exposição ao sol sobre todas as variáveis fisiológicas ao longo do dia (P<0,01). O gradiente térmico favorável no período noturno atenuou os efeitos do estresse térmico não constatando o efeito da exposição a radiação solar direta sobre os constituintes sanguíneos. No experimento 3que objetivou quantificar a velocidade de aquisição de calor ao sol comparando-a posteriormente com a velocidade de dissipação do calor à sombra, constatamos que a exposição por uma hora ao sol incrementou a frequência respiratória em 189,24 % e a temperatura retal em 1,46 %, após o retorno a sombra, por uma hora, verificamos uma redução de 191,75 % e 0,57 %, respectivamente. No experimento 4avaliamos a dinâmica da termólise evaporativa e o balanço térmico de radiação e convecção em condições de radiação solar direta. À medida que reduz a temperatura radiante média, os animais passam a perder o calor armazenado por radiação, reduzem as perdas por polipnéia térmica ao passo que as perdas por sudação permanecem altas. / The aim of the study was to evaluate the thermoregulatory mechanisms, based on a temporal approach, in relation to different heat storages provided by different types of thermal environments (with and without solar radiation). Twelve Mediterranean buffalo heifers were submitted to four experiments during the summer of 2010 to 2012 outlined to achieve specific objectives. Environmental parameters dry bulb temperature; wet bulb temperature; relative humidity; winds speed and black globe temperature were measured. Physiological parameters rectal temperature; base of tail temperature; skin temperature; hair coat surface temperature; respiratory rate and sweating rate were measured. The statistical analysis were done with the assistance of the Statistical Analysis System, version9.1.3(SAS Institute Inc., Cary, NC, USA), using procedures UNIVARIATE,CORR, GLM and MIXED. The first experiment aimed to verify the thermoregulatory reactions of the warm environment in the climatic chamber. Increasing the air temperature in a controlled environment influenced all physiological variables throughout the day (P<0,01). The increase in the sweating rate during heat stress led to the depletion of plasma potassium (P=0,0051). In experiment 2, which assessed the thermoregulatory reactions in the presence of direct solar radiation, it was observed the influence of sun exposure on all physiological variables throughout the day (P<0.01). The favorable thermal gradient at night attenuated the effects of heat stress without identifying the effect of direct sun exposure on blood constituents. In experiment 3, that aimed to measure the heat acquisition rate under the sun subsequently comparing it with the speed of heat dissipation under the shade, it was observed that one hour exposure to the sun increased respiratory rate at 189,24 % and rectal temperature at 1,46 %. After returning the shade for one hour, it was found reductions of 191,75 % and 0,57 %, respectively. The Experiment 4 evaluated the dynamics of evaporative thermolysis and thermal balance of radiation and convection under conditions of direct solar radiation. Reducing the mean radiant temperature, the animals started to lose the stored heat by radiation, reduced losses by thermal polipneia while the losses by sweating remain high.

Orientador: Rosana Marta Kolb / Resumo: O Cerrado é considerado o segundo maior bioma brasileiro em extensão, com ampla diversidade de espécies e endemismo. Nas últimas décadas, áreas de Cerrado vêm sofrendo alterações fitofisionômicas, devido principalmente à ausência do fogo. A sua ausência tem possibilitado que áreas de cerrado stricto sensu sejam invadidas por espécies arbóreas, levando ao adensamento da vegetação, que por sua vez, reduz a riqueza de espécies não lenhosas, por diminuição da luminosidade. Assim, o presente estudo avaliou as respostas de três espécies não arbóreas típicas do cerrado stricto sensu em condições artificiais de sombreamento, a partir de observações fenológicas da mortalidade e capacidade de rebrota, além da análise de parâmetros fotossintéticos. Após 14 meses de experimento, a taxa de mortalidade foi de 43% para as plantas sombreadas, enquanto que as controles (plantas não sombreadas) tiveram uma mortalidade de 10%. As espécies avaliadas (Hyptis campestris, Cissampelos ovalifolia e Lepidaploa chamissonis), quando sombreadas, apresentaram menor ponto de saturação e de compensação luminoso e menor assimilação de carbono, demonstrando potencial de aclimatação. Contudo, plantas sombreadas estão abaixo do ponto de saturação de luz, o que junto com as rebrotas sucessivas pode ter levado ao exaurimento das suas reservas, comprometendo sua sobrevivência. Desta forma, o adensamento vegetacional pode ser um risco para a preservação de plantas não arbóreas de Cerrado. / Abstract: The Cerrado is considered the second largest Brazilian biome in extension, with wide species diversity and endemism. In the last decades, areas of Cerrado have undergone phytophysiognomic alterations, mainly due to the absence of fire. Its absence has allowed tree species to invade areas of cerrado stricto sensu, leading to the densification of vegetation, which in turn reduces the richness of non-woody species, due to the reduction of luminosity. Thus, the present study evaluated the responses of three non-arboreal species typical of cerrado stricto sensu under artificial shading conditions, based on phenological observations of mortality and resprouting capacity, as well as the analysis of photosynthetic parameters. After 14 months of experiment, the mortality rate was 43% for shaded plants, while the controls (unshaded plants) had a mortality of 10%. The evaluated species (Hyptis campestris, Cissampelos ovalifolia and Lepidaploa chamissonis), when shaded, showed lower saturation point and light compensation point and lower carbon assimilation, showing acclimatization potential. However, shaded plants are below the point of saturation of light, which along with the successive resprouts can have led to the exhaustion of their reserves, compromising their survival. In this way, vegetational densification may be a risk for the preservation of non-arboreal Cerrado plants. / Mestre

In the Central Valley of Costa Rica in the Department of Heredia, I investigated the soil chemical properties and microbial communities under four native shade tree species in a coffee agroforestry system. In the second year of the study, Effective Microorganisms, a microbial inoculant, was applied to examine its effect on soil chemistry. The shade tree species included in this study were Anonna muricata L., Diphysa americana Mill., Persea americana Mill., and Quercus spp. L. Plots measured 20 by 30 meters and were replicated three times for each shade tree species except for Quercus spp., which only had two replications. Twelve composite soil samples were collected from each plot in 2008 and again in 2009, and twelve composite foliar samples were taken from the coffee plants in each plot in 2008. The results of this study indicated that the species of native shade tree had a significant effect on soil ammonium-N, nitrate-N, total dissolved nitrogen and magnesium. Sun or shade position had a significant effect on dissolved organic nitrogen and dissolved organic carbon. The species of native shade tree also had a significant effect on the composition of soil microbial communities. PLFA analysis revealed a significant difference in soil fungi abundance in soil samples from Annona plots relative to those from Persea plots. Effective microorganisms in combination with the tree species, as well as in combination with species and sun or shade position, had a significant interaction effect on soil ammonium-N, with the EM-treated plots showing higher concentrations of soil ammonium-N. There was a significant positive correlation between soil pH and foliar calcium, as well as soil dissolved organic nitrogen and foliar %N, at p< 0.01. This study suggests that Quercus spp. is a tree species that may help to regulate the cycling of nitrogen in the coffee agroecosystem. Annona muricata appears to inhibit the action of some fungal species and may reduce the occurrence of fungal pathogens in the soil, although the present study did not explore this issue. Although Diphysa americana is a legume, it does not appear to increase the amount of soil nitrogen in the vicinity of the coffee plants themselves. All four tree species in this study improve coffee soils by increasing soil concentrations of dissolved organic nitrogen and dissolved organic carbon. Coffee yield data and long term observations on the health of the coffee plants would clarify whether one of these species is particularly beneficial, from an agronomic perspective, for the productivity of this coffee agroecosystem.

Thesis--Auburn University, 2010. / Abstract. Includes bibliographic references

Agroforestry production methods present one option for addressing growing concerns about the long term sustainability of intensive coffee production techniques. A study was designed to compare the effects of fertilization and shading from two leguminous species, Erythrina poeppigiana and Chloroleucon eurycyclum, on coffee grown at a Costa Rican research site. Coffee below biannually pruned, conventionally fertilized Erythrina exhibited the highest photosynthetic performance under both low and high light levels as well as greater biomass and higher N concentration. Soil P did not affect coffee performance, although shade trees on sites with higher soil P fixed more N compared to trees grown on low P sites, most of which were not found to be fixing. Results suggest shade mechanisms are the most important drivers of coffee adaptation in coffee agroforestry systems, though proper soil nutrient management and legume species pairing also appear to augment coffee response to microclimate conditions.

Agroforestry production methods present one option for addressing growing concerns about the long term sustainability of intensive coffee production techniques. A study was designed to compare the effects of fertilization and shading from two leguminous species, Erythrina poeppigiana and Chloroleucon eurycyclum, on coffee grown at a Costa Rican research site. Coffee below biannually pruned, conventionally fertilized Erythrina exhibited the highest photosynthetic performance under both low and high light levels as well as greater biomass and higher N concentration. Soil P did not affect coffee performance, although shade trees on sites with higher soil P fixed more N compared to trees grown on low P sites, most of which were not found to be fixing. Results suggest shade mechanisms are the most important drivers of coffee adaptation in coffee agroforestry systems, though proper soil nutrient management and legume species pairing also appear to augment coffee response to microclimate conditions.

No description available.

No description available.

Οι μορφολογικές, φυσιολογικές και βιοχημικές προσαρμογές των φυτών (ή φύλλων) με διαφορετική έκθεση στην ηλιακή ακτινοβολία (σε συνθήκες πλήρους φωτός ή φυσικής σκίασης στο εσωτερικό της φυτικής κόμης) έχουν μελετηθεί και καταγραφεί λεπτομερώς. Στην παρούσα εργασία επανεξετάσαμε κάποιες από τις φυσιολογικές αυτές προσαρμογές, εκμεταλλευόμενοι τα πλεονεκτήματα της χρήσης σύγχρονων μεθόδων μέτρησης του in vivo φθορισμού της χλωροφύλλης. Επίσης, διερευνήθηκε η ύπαρξη προσαρμογών της φωτοσυνθετικής συσκευής σε διαφορετική ένταση φωτός, οι οποίες δεν ήταν είχαν μελετηθεί διεξοδικά. Πιο συγκεκριμένα, χρησιμοποιήθηκαν διαφορετικές τεχνικές φθορισμομετρίας, με τις οποίες μελετήθηκαν συγκριτικά αφ’ ενός οι κβαντικές αποδόσεις και οι περιορισμοί στα επιμέρους στάδια της φωτοσυνθετικής ροής ηλεκτρονίων και αφ’ ετέρου το ποσοστό συμμετοχής της κυκλικής ροής ηλεκτρονίων γύρω από το PSI και της φωτοαναπνοής στα φύλλα φωτός και σκιάς. Με βάση τα αποτελέσματά μας, θεωρούμε ότι το JIP-test μπορεί να προσφέρει αξιόπιστα και αξιοποιήσιμα αποτελέσματα. Πιο συγκεκριμένα, στα φύλλα που είναι προσαρμοσμένα στη σκιά φαίνεται να υπάρχει ένα εμπόδιο στη γραμμική ροή ηλεκτρονίων που εντοπίζεται γύρω από το φωτοσύστημα Ι. Οι παράμετροι που υποδεικνύουν αυτή την κατάσταση δείχνουν ότι περιοριστικός παράγοντας της ροής ηλεκτρονίων φαίνεται να είναι το μικρότερο ποσό των ενεργών κέντρων του PSI (1-VI) σε συνδυασμό με τα μικρότερα αποθέματα των τελικών αποδεκτών ηλεκτρονίων του (1/VI). Αυτό επιβεβαιώνεται από τη μικρότερη πιθανότητα μεταφοράς των ηλεκτρονίων από τους ενδιάμεσους φορείς στους τελικούς αποδέκτες ηλεκτρονίων του PSI (δRo) στα φύλλα σκιάς. Επιπρόσθετα, στην πλειοψηφία των φυτικών ειδών που εξετάστηκαν, η διαφορετική ποιότητα φωτός που δέχονται τα φύλλα σκιάς (φως εμπλουτισμένο σε βαθύ ερυθρό, που διεγείρει επιλεκτικά το PSI) σε σχέση με τα φύλλα φωτός φαίνεται να αυξάνει την κυκλική ροή ηλεκτρονίων γύρω από το PSI. Σε αυτά τα είδη οι προαναφερθείσες παράμετροι του JIP-test έχουν καλή συσχέτιση με το μέγεθος της κυκλικής ροής ηλεκτρονίων. Τέλος, μελετώντας τη φωτοαναπνοή, προκύπτει ότι στα φύλλα φωτός το ποσοστό του κύκλου C2 αυξάνεται με την αύξηση της φωτεινής ακτινοβολίας. Τα φύλλα σκιάς από την άλλη, φαίνεται να έχουν ένα όριο ως προς την προσαρμογή τους σε υψηλές εντάσεις φωτός. / The morphological and biochemical adjustments of plant leaf to high and low light intensity have been widely studied and recorded over the past years. In the present work, some of those physiological adjustments have been re-evaluated with the use of modern methods. In parallel, novel aspects of the light/shade acclimation syndrome were sought. Our results indicate that the JIP-test is quite useful for assessing parameters related to the function of both photosystems. In shade leaves, a lower content of PSI reaction centers (1-VI) combined with a smaller pool size of final electron acceptors of PSI seem to create an obstacle in linear electron flow around photosystem I. This is confirmed by the lower efficiency of electron transfer between intermediate carriers to the reduction of end electron acceptors of PSI (δRo). In addition, in the majority of plant species examined, shade leaves have higher rates of cyclic electron flow around PSI, which is probably caused by the quality of incident light (enriched in far red, FR). In these species there is good correlation between cyclic electron flow and the JIP-test parameters mentioned above. Photorespiration is known to be higher when the plant is under stress. Light acclimated leaves seem confirm that theory as they have higher oxygenase activity of Rubisco with increasing light intensity. On the other hand, shade leaves seem unable to fully adjust to very high light intensity.

Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2007. / The production of high quality fruit that meet international standards is of vital importance to the South African fruit industry. Detrimental climatic conditions are forcing producers to examine alternate production methods. In this study the effect of protective netting on apple tree (Malus domestica) physiology, microclimate and fruit quality was investigated to determine the potential of apple production under netting in the Western Cape Province of South Africa. The influence of 20% black shade netting on the photosynthetically photon flux density, leaf and fruit surface as well as air temperature was measured on four blush apple cultivars over a two year period in the Koue Bokkeveld area, in the Western Cape, South Africa. Measurements were also taken on leaf gas exchange, including net CO2 assimilation rate under ambient and saturating CO2 conditions, stomatal conductance, and transpiration rate. A decrease in light conditions of 22 - 31% was measured under black netting thus reducing the amount of light available to the plant significantly. Leaves under the netting were cooler by 1.7 – 3.9°C on a milder day (11 January 2005) and by 4.3 – 6.2°C on a hot day (28 February 2005) than control leaves. Fruit surface temperature under the netting was cooler by 0.7 - 2.9°C on milder days, and by 4.0 - 5.3°C on a hot day (28 February 2005) than control fruit. Significant increases in CO2 assimilation, stomatal conductance and transpiration were found under the netting. Netted treatments also showed a lower leaf vapour pressure deficit and tended to be less water stressed having higher leaf water potential than the control treatments. Differences in leaf nitrogen were not significant between treatments except for ‘Cripps’ Pink’ where non netted treatments had higher leaf nitrogen levels than the netted treatments during the 2004 season. Heat tolerance and the ability to recover after exposure to different temperatures for different lengths of time, was evaluated for the same four blush apple cultivars grown under protective netting. The results showed that fruit taken from the netted treatments had a higher incidence of injury based on chlorophyll fluorescence measurements, and did not recover well at temperatures higher than 45°C. The higher tolerance of the non-netted fruit at 45°C could be due to better acclimation to high light and heat levels than the fruit from the netted treatment. Fruit quality of ‘Royal Gala’, ‘Fuji’, Cripps’ Pink’ and ‘Braeburn’ was evaluated for netted and non-netted treatments as well as between five different crop loads as sun-treatments. It was found that cultivars reacted differently to the altered microclimate under the netting. Significant interaction between net and crop load treatments was found for fruit mass of ‘Royal Gala’ and ‘Fuji’. Fruit mass declined more rapidly with increased crop load under nets than in the open. The net treatment reduced sunburn significantly in all the cultivars except ‘Cripps’ Pink’. Ground colour was found to be positively influenced by netting on ‘Braeburn’ and during 2005 on ‘Royal Gala’. Blush colour was reduced under the netting for ‘Braeburn’ and ‘Fuji’ and unaffected for ‘Royal Gala’ and ‘Cripps’ Pink’. Fruit firmness, total soluble solids and titratable acidity, were reduced under nets for most of the cultivars. Netting thus seems to have a positive effect in reducing sunburn damage but a varying effect on other fruit quality parameters, which seem to be cultivar specific. The influence of black protective netting on vegetative growth was determined by measuring total prunings and trunk circumference. Reproductive bud development analysis was also done. An increase was found in summer prunings for ‘Fuji’ and ‘Cripps’ Pink’ which was most likely due to the topping of the trees to prevent them from growing into the netting. Seasonal trunk growth was affected significantly for ‘Braeburn’ with a higher percentage recorded under the netting. Reproductive bud development was higher for the netted treatments and on trees with lower crop loads. Photosynthetic photon flux density was reduced significantly in a ‘Granny Smith’ orchard at harvest by black, blue and grey type netting. Sunburn was significantly reduced under the black and blue netting. Fruit mass was higher under the netted treatments during the second season of measurements. Firmness and total soluble solids were lower under the netting. Blush colour was found to be significantly lower under the black netting. Seed viability, ground colour, titratable acidity, starch breakdown, stem end russet and the occurrence of Fusicladium pyrorum damage was unaffected by the netting.