Quercus robur et Quercus petraea sont deux espèces de chêne sympatriques occupant des niches écologiques distinctes et présentant des différences de sensibilités à la sécheresse. La littérature disponible suggère qu’il existe des différences inter-spécifiques stables de l’efficience d’utilisation entre ces deux espèces, Q.petraea présentant des valeurs supérieures à Q.robur. L’efficience d’utilisation de l’eau peut être étudiées à différentes échelles d’intégration spatiales et temporelle. Sur la base de mesures instantanées d’échanges gazeux foliaires, l’efficience d’utilisation de l’eau intrinsèque (Wi) peut être déterminée. D’autre part, l’efficience d’utilisation de l’eau peut être caractérisée par des mesures de composition isotopique du carbone (δ13C) au sein des tissus végétaux ou par l’estimation de l’efficience de transpiration plante entière (TE), permettant ainsi une estimation de l’efficience intégrée dans le temps. La caractérisation de l’efficience à travers ces différents estimateurs a permis de mettre en évidence chez des semis croissant en conditions contrôlées une efficience de transpiration supérieure chez Q.robur bien qu’aucune différence ne soit détectable entre les deux espèces sur la base des mesures instantanées (Wi). Ces variations de TE étaient essentiellement liées aux variations de la production de biomasse par les plants tandis que les variations de Wi qui ont été observées étaient principalement associées à la conductance stomatique. Les variations intra et inter espèces de la dynamique de réponse stomatique au changement abrupte d’un facteur environnemental (lumière, CO2, VPD) n’ont pu être clairement reliées aux variations des différents estimateurs de l’efficience ou leur composantes respectives. Par ailleurs, les conditions de stress hydriques impactaient la dynamique de réponse stomatique chez les deux espèces de chênes. Cet impact se traduit par des réponses stomatiques plus rapides. Les principales différences observées entre les espèces étaient liées à la production de biomasse. Les deux espèces affichaient en effet des stratégies d’allocation du carbone divergentes notamment au niveau du compartiment racinaire. Ainsi Q.petraea produisait un système racinaire plus fin et ramifié que Q.robur. Par ailleurs, cet état de fait était plus marqué sous conditions de stress, conditions à laquelle Q.robur est plus sensible que Q.petraea en terme de production de biomasse. La complexité des relations entre efficience d’utilisation de l’eau et l’ensemble des traits physiologiques et anatomiques étudiés ainsi que leurs possibles implications dans la tolérance à la sécheresse des deux espèces de chênes sont discutées dans cette synthèse. / Quercus robur L. and Quercus petraea (Matt.) Liebl. are two sympatric oak species occupying distinctive ecological niches as well as presenting disparate drought tolerances. Available litterature reports the existence of stable inter-specific differences of water use efficiency (WUE) between the two species, Q. petraea displaying higher values than Q. robur. Water use efficiency can be studied at several integration scales both spatially and temporally. Based on instantaneous foliar gaz exchange, the intrinsic water use efficiency can be determined (Wi). On the other hand, water use can be characterised by measurements of the carbon isotopic composition of plant tissues (13C) or by estimation of the whole plant transpiration efficiency (TE), thus allowing a time-integrated estimate of water use. The characterisation of WUE through these different estimators allowed us to put in evidence in oak seedlings grown under controlled conditions a higher transpiration efficiency in Q. robur even though no differences were observed between the two species regarding instantaneous measurements (Wi). TE variations were mainly linked to the variations of the biomass production by the plants while Wi variations were essentially associated to the stomatal conductance. Both intra and inter specific variations of the dynamics of stomatal response to step changes of environmental factors (light, CO2, VPD) could not be clearly linked to the variations of the different WUE estimates nor their respective components. Nevertheless, drought conditions impacted the stomatal dynamics in both species towards faster stomatal responses, especially for stomatal closing. Furthermore, the main observed differences between species were linked to biomass production. Both species displayed different carbon allocation strategies, especially regarding the root compartment. Thus, Q. petraea produced a significantly more ramified and thinner root system than Q. robur. Such behaviour was accentuated under drought stress, under which Q. robur was more sensitive than Q. petraea in term of biomass production. The complexity of the relationships between water use efficiency and all of these morphological and physiological traits as well as the possible drought tolerance implications in both oak species are discussed in this PhD thesis.

Stormwater bioretention cells (BRCs) are a variety of green stormwater infrastructure with the potential to restore pre-urban water balance, provided they can be tailored to infiltrate and evapotranspire (i.e., harvest) urban runoff in proportions consistent with pre-urban hydrologic conditions. This paper evaluates their capacity to do so, focusing on evapotranspirative harvest, which is relatively understudied, and the capacity of CSR (Competitve, Stress-tolerant, and Ruderal) functional type to serve as an overarching framework characterizing the water use strategy of BRC plants. The goal is to determine if harvest (and therefore the ratio of urban runoff infiltrated to harvested; the I:H ratio) might be fine-tuned to meet pre-urban values in BRCs through informed manipulation of plant community composition. This study focuses on 3 critical plant water use traits, the turgor loss point, the point of incipient water stress, and maximum stomatal conductance. A global plant traits meta-analysis identified degree of plant competitiveness and stress tolerance as significant determinants of all three water use traits, with stem type (woody vs herbaceous) also being significant, but only for turgor loss point. Based on these results, six water use scenarios appropriate for plants with different CSR type/stem type combinations were developed. BRC plants spanning the range of CSR types necessary to actionize these scenarios were determined to be available in eight major climate zones of the coterminous US, suggesting that regulating plant water use in BRCs using CSR is likely feasible. Hydraulic simulations (Hydrus 1D) were conducted for each scenario in all eight climate zones and revealed significant differences in evapotranspirative harvest and I:H ratios in simulated BRCs. Competitive woody plants had the highest evapotranspiration and lowest I:H ratios; 1.5-1.8 times more evapotranspiration and a 1.6-2 times lower I:H ratio than stress tolerant herbaceous plants, on average, across climate zones. Despite these significant differences, no simulated BRC in any climate zone was capable of reproducing pre-urban I:H ratios, regardless of plant type. More water was infiltrated than harvested in all scenarios and climates with the inverse being true for all pre-urban conditions. This suggests that absent additional sources of harvest (e.g., use of BRC water for nonpotable purposes such as toilet flushing and outdoor irrigation, or adoption of novel BRC designs that promote lateral exfiltration, stimulating "extra" evapotranspiration from nearby landscapes), BRCs will be unable to restore pre-urban water balance on their own. If true, then using BRCs in combination with other green technologies (particularly those biased towards harvest), may be the best path forward for balancing urban water budgets. / Master of Science / Stormwater bioretention cells (BRCs) are a variety of green infrastructure designed to manage urban stormwater flows that can dramatically reduce the amount of stormwater that is rapidly (and unnaturally) conveyed from paved surfaces to ecosystems. Their ability to recreate natural flow conditions is dependent on them balancing rates of infiltration – slowly filtering water down to the water table – and evapotranspiration – letting plants capture and transpire water. This paper evaluates the extent to which different plant functional types (competitive, stress tolerant, and ruderal (weedy)) can be used to regulate this balance, bringing urban hydrologic conditions closer to pre-urban ones. Competitiveness and stress tolerance were found to significantly influence plant water use traits, as was plant stem type (woody vs herbaceous) to a lesser extent (i.e., managing water budgets using CSR functional type is theoretically possible). Published BRC vegetation guidelines in 8 major US climate zones were found to include both competitive and stress tolerant species (i.e., the range of functional types required to regulate BRC water balance exists, suggesting it is feasible). Finally, hydraulic simulations conducted under six plant water use scenarios (reflecting different CSR types and stem types) revealed significant differences in the ratio of water infiltrated to evapotranspired by BRCs (i.e., changing plant functional types can meaningfully influence BRC water balance). This said, the magnitude of this effect may be insufficient to return urban catchments to a pre-urban state. All BRCs infiltrated too much water in our simulations suggesting that absent additional sources of harvest (for instance., use of BRC water for nonpotable purposes such as toilet flushing or outdoor irrigation), BRCs will be unable to restore pre-urban water balance on their own. If true, then using BRCs in combination with other green technologies (particularly those biased towards harvest), may be the best path forward for balancing urban water budgets.

Master of Science / Department of Agronomy / Robert M. Aiken / Mary B. Kirkham / Transpiration efficiency (TE) is defined as total biomass produced per unit of water transpired. Improvement of TE means maximizing crop production per unit of water used. The objectives of the study were to examine, at the leaf level and the whole plant level, the variation in TE for sorghum [Sorghum bicolor (L.) Moench] accessions, previously screened for TE and to test physiological mechanisms that may account for differences in TE. Three field studies and two mini-lysimeter studies (one done in pots under greenhouse conditions and one done in pots in the field) were conducted with eight accessions. Instantaneous measurements of assimilation (A), stomatal conductance (gs), and transpiration by gas exchange provided measures of the transpiration efficiency at the leaf level. Growth observations and soil water balance in field plots quantified components of whole-plant TE. Growth and development measurements showed significant difference, explaining the existence of photoperiod sensitivity among the sorghum genotypes. Assimilation (A), stomatal conductance (gs), and maximum quantum efficiency of photosystem II (Fv/Fm) were consistently greater for accession PI533946 (from India) and greater for accession PI295121 (from Australia) in both field and the field-pot studies (p<0.05). Internal carbon dioxide (Ci), an indicator of intrinsic transpiration efficiency, differed among lines under field conditions (p<0.05). Leaf relative water content (RWC), measured in the greenhouse, and did not differ among the eight accessions. No consistent differences in biomass and water use were detected among lines under field conditions. In conclusion, developing reliable selection indices for TE will require a greater understanding of whole-plant physiological processes to utilize the differences in TE observed at the leaf level.

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)

La zone sahélienne a connu une baisse des précipitations et d’importants changements d'utilisation des terres ces dernières décennies qui ont conduit à une forte régression du couvert ligneux. Pourtant, Guiera senegalesis J.F. Gmel est une Combretaceae semi-sempervirente, dont la dominance s'est accrue avec la pression agricole dans la bande soudano-sahélienne où elle joue un rôle socio-économique et agroforestier important. Elle constitue donc un bon modèle pour étudier les réponses hydriques du couvert ligneux actuel à la sécheresse et les modifications de ces réponses sous l'effet de la coupe.Les objectifs de ce travail de thèse étaient : 1) de caractériser et quantifier les processus de régulation hydrique chez G. senegalensis et de déterminer ses limites fonctionnelles, afin d’estimer sa marge de sécurité dans ses conditions actuelles de croissance, 2) d’estimer l’effet de la coupe annuelle sur ses processus de régulation et 3) d’analyser les variations de ses traits foliaires en fonction de la saison et des conditions de croissance.Les mesures et les observations ont été réalisées d’avril 2009 à février 2011 sur une jachère âgée, sur une jeune jachère et sur deux champs de mil adjacents aux deux jachères respectivement. A l'échelle de l'arbuste, le potentiel hydrique foliaire et la conductance stomatique ont été mesurés au cours de ces deux saisons de croissance sur un échantillon d'arbustes dans les trois types de couvert. Le taux de transpiration foliaire et la conductance hydraulique sol-feuille en ont été déduits. A l’échelle du rameau, ont été suivi la dynamique du nombre de feuilles, de la surface moyenne des feuilles, du diamètre moyen des tiges qui les portent. La durée de vie moyenne des feuilles et leur masse surfacique ont été mesurées. La courbe de vulnérabilité à la cavitation de l'espèce, qui est la perte de la conductivité hydraulique en fonction du potentiel hydrique, a été réalisée à partir de plusieurs segments de branches passés au CAVITRON en laboratoire.Les principaux résultats obtenus sont que la fermeture des stomates qui permet à l’espèce de réguler ses pertes en eau a lieu à un niveau faible de cavitation du xylème (30%). Ainsi, l’espèce peut survivre dans les conditions sahéliennes grâce à une « marge de sécurité » positive de +0,6 MPa. La régulation stomatique couplée à un ajustement foliaire permet à l’espèce de maintenir son équilibre hydrique au cours de la saison sèche chez les arbustes matures non perturbés. La baisse des potentiels hydriques foliaires de base et minimum en réponse à la sécheresse saisonnière est isohydrodynamique et est plus élevé chez les arbustes matures, suggérant que les repousses de l'année sont moins stressées. De plus, la coupe a pour effet de découpler l’ajustement foliaire de la régulation stomatique et entraîne une production de feuilles et une croissance des jeunes rameaux continues tout au long de l'année chez les repousses, grâce à une conductance hydraulique sol-feuille deux fois plus élevée que chez les arbustes matures. Enfin, la durée de vie des feuilles s’allonge avec l’âge des rameaux d'une année comme avec l'âge du peuplement, tandis que la masse surfacique foliaire augmente progressivement de la même façon quand on passe de la saison des pluies à la saison sèche, quel que soit l'âge du peuplement.Ces traits fonctionnels contribuent à ce que l’espèce puisse à la fois résister aux conditions de sécheresse dans lesquelles elle croît et ré-allouer de façon intense des ressources, stockées probablement dans les racines, à la reconstruction rapide de sa partie aérienne à la suite d'une coupe. Les limites d'une telle stratégie restent cependant à identifier, en particulier le seuil d'épuisement des ressources sous l'effet de la répétition annuelle des coupes. / Sahel suffered from severe rainfall decreases combined to great changes in land use during the last decades that led to strong decrease in the woody cover. However, Guiera senegalesis J.F. Gmel is a semi-evergreen Combretaceae whose dominance rose with crop pressure in the Sudano-Sahelian band where it plays an important socio-economic role through agroforestry. Consequently, this is a good model to study hydric responses of the present woody cover to drought and the effect of cutting on these responses.The aims of this work were: 1) to characterize and quantify hydric regulation processes in G. senegalesis and to determine its specific functional limits, in order to estimate its safety margin in its current growth conditions, 2) to estimate cut effect on these processes and 3) to analyze variations of its leaf traits according to the season and its specific growth conditions.Measurements and observations were conducted from April 2009 to February 2011 on an old fallow, on a young fallow, and on the two crop fields adjacent to the two fallows respectively. At the shrub scale, leaf water potential and stomatal conductance were measured during the two growing seasons on shrub samples in the three cover type. The leaf transpiration rate and the soil-to-leaf conductivity were deduced. At the stem scale, the dynamics of the number of leaves, the mean leaf area (LMA), the mean diameter of the stems that carry them, the mean leaf life span, and the leaf mass per area were monitored. The species vulnerability curve to cavitation, which is the loss of conductivity as a function of the water potential, was obtained from several peaces of branches treated in a CAVITRON at the laboratory.The main results obtained were that the stomatal closure that allows species to regulate its water loss occurs at a low rate of xylem cavitation (30%). Thus, the species can survive in its Sahelian conditions thanks to a positive “safety margin” of +0.6 MPa. Stomatal regulation coupled with leaf adjustment allows the species to maintain its water balance during the dry season in mature and undisturbed shrubs. The decrease in predawn and midday leaf water potentials in response to seasonal drought was isohydrodynamic, and it was greater in mature shrubs, suggesting that current year resprouts are under less stress. In addition, cutting decouple leaf adjustment from stomatal regulation, leading to continuous leaf production and young stem growth all over the year, thanks to a soil-to-leaf conductivity seven times higher in the current year's resprouts than in the mature shrubs. Finally, leaf life span increases with the current year's stem age as well as with the stand age, while the LMA progressively increases from the rainy season to the dry season, similarly whatever the stand age.These functional traits contribute to the species resistance to the drought conditions under which it grows, but also, following the cutting, to intensively re-allocate resources, probably from the root reserve, to the fast re-building of the aerial part. However, the limits of such a strategy remain to be identified, especially the resource exhaustion threshold under repetitive yearly cutting.

Regarding the vegetation, the most affected areas by high levels of surface ozone (O3) are the mountain ridges. Our study has been carried out in the Jizerske hory Mts. High O3 levels together with the convenient environmental conditions for stomatal conductance could be a threat for the health of recovering ecosystems in this area. The aims of this study was both to assess the influence of O3 on vegetation in the Czech mountains and to provide recommendations and outlooks for possible future using of relatively new methods (visible symptoms and stomatal O3 flux modelling) used for O3 impact assessment on native vegetation in the field; that means physiologically relevant methods for the determination of O3 influence. During 2006 and 2007, O3-like visible symptoms were assessed on the leaves of seven species at four sites. Symptoms on only two species (Fagus sylvatica L. and Rubus idaeus L.) have been determined as O3-induced. To our knowledge, it is the first study in the Czech Republic in which the O3-like symptoms on native plants have been verified by the Ozone Validation Centre for Central Europe. Our results based on O3-induced symptoms indicate that ambient O3 is likely to have a much lower impact than expected, considering the measured O3 concentrations (measured with passive samplers) and...

As relações hídricas e fisiológicas em plantas de lima ácida ‘Tahiti’ sob estresse hídrico foram estudadas tendo-se como principais objetivos: (a) verificar a sazonalidade da evapotranspiração e o coeficiente de cultivo com o uso de lisímetro de pesagem baseado em célula de carga eletrônica, (b) determinar o limite crítico da água disponível em função da evapotranspiração, trocas gasosas e potencial de água na folha durante um período de estresse hídrico e (c) avaliar o efeito da supressão da irrigação durante diferentes períodos fenológicos sobre o desenvolvimento vegetativo, na produtividade e qualidade do fruto. Este experimento foi conduzido na Fazenda Areão do Departamento de Engenharia Rural da ESALQ/USP, em Piracicaba, SP, em um pomar de 1 hectare no espaçamento de 7 X 4 m com lima ácida ‘Tahiti’ (Citrus latifolia Tanaka) enxertadas em citrumelo ‘Swingle’ [Poncirus trifoliata (L.) Raf. x C. paradisi Macf.] irrigadas por gotejamento. Para as medidas fisiológicas, foram utilizados equipamentos portáteis como a câmara de pressão e analisador de gases por infravermelho além de medidas do desenvolvimento vegetativo e produtivo. O monitoramento da água solo foi realizado por tensiômetros e sondas de TDR. A Evapotranspiração de Referência foi obtida com uma estação agrometeorológica automatizada presente na área. Verificou-se um efeito sazonal na evapotranspiração, com uma redução superior a 50% no período verãoinverno, possibilitando a economia da irrigação no período. A evapotranspiração, trocas gasosas e potencial da água na folha ao amanhecer foram diminuídos pelo esgotamento de 40% da água disponível do solo por ocasião do final do período de inverno. A supressão da irrigação no período de Setembro a Março diminuiu o potencial matricial do solo e promoveu um estresse leve nas plantas não-irrigadas, não se observando efeitos negativos no desenvolvimento vegetativo, produtivo e na qualidade dos frutos formados. Recomenda-se o potencial da água no folha ao amanhecer para manejo da irrigação, mantendo-o maior que -0,6 MPa, para evitar o estresse hídrico em plantas de limeira ácida ‘Tahiti’. / Water and physiologic relations in acid lime trees under water stress were studied with the following purposes: (a) to verify the seasonal effect of evapotranspiration and the crop coefficient in non-stressed trees by weighing lysimeter; (b) to determine the critical soil water depletion for evapotranspiration, gas exchange as well as the leaf water potential during a stage of growing of the trees and (c) to determine the effect of the irrigation suppression on growth, yield and fruit quality during different phenological periods. The experiment was carried out an experimental farm at College of Agriculture Luiz de Queiroz (ESALQ), in Piracicaba and performed from 2003 to 2005 in a 1 hectare orchard planted with ‘Tahiti’ (Citrus latifolia Tanaka) grafted on ‘Swingle’ [Poncirus trifoliata (L.) Raf. x C. paradisi Macf. ] rootstock. The trees were spaced 7 x 4 m apart and drip-irrigated. For physiologic measurements were used portable equipments such as a pressure chamber and an infrared gas analyzer as well measurements of vegetative and productive growth. The soil water status was monitored by tensiometers and TDR probes. The reference evapotranspiration was obtained by an automatic weather station presented on the area. There was a seasonal effect on evapotranspiration with a reduction higher than 50% forward to summer-winter, being able to water savings in the period. The evapotranspiration, gas exchange and leaf water potential at predawn were decreased when the soil water available was depleted by 40% in the end of winter. The irrigation suppression from September and March decreased the soil matric potential and promoted a light stress level in non-irrigated trees, but without negative effects on vegetative, productive and fruit quality. We recommend the leaf water potential at predawn for irrigation scheduling, keeping higher than -0.6 MPa for avoid water stress in acid lime trees.

Atualmente, o mercado no Brasil de adjuvantes é de aproximadamente 400 milhões de dólares, sendo que a maior parte são os óleos, o que demonstra o pouco conhecimento sobre o uso de adjuvante organossiliconado. Foi realizada extensa revisão de literatura na Internet, Associações, Empresas privadas, bem como opinião de Especialistas. Pode-se concluir que os organossiliconados podem ser usados para herbicidas, fungicidas, inseticidas, reguladores vegetais, fertilizantes foliares e biopesticidas, devido às características toxicológicas e ambientais favoráveis, bem como os benefícios de melhoria da ação dos produtos, destacando-se a melhor performance em termos de penetração, absorção, retenção e cobertura de ingrediente ativo devido ao conceito de fluidez estomatal e penetração cuticular, que pode permitir redução do volume de água evitando a perda por escorrimento e permitindo melhor eficiência no manejo de problemas fitossanitários. Os adjuvantes organossiliconados não são iguais. Para se obter melhores resultados, é importante considerar: (i) as condições ambientais, (ii) as espécies vegetais, (iii) os sistemas de aplicação, (iv) o sistema de cultivo como um todo, (iv) os ingredientes ativos e (v) o alvo. A criação de uma regulamentação clara e simples é necessária, utilizando a normatização existente nos Estados Unidos como referência. Conforme discutido no Workshop sobre Adjuvantes Agrícolas no Brasil, promovido pelo Ministério da Agricultura, Pecuária e Abastecimento, o adjuvante deve ser tratado como um produto químico, o qual estará sendo combinado com os produtos agroquímicos existentes no mercado. Quanto às demandas de pesquisa, sugere-se estudar os diferentes adjuvantes organossiliconados com relação às suas propriedades, bem como as possibilidades de novas combinações personalizadas que forneçam o melhor desempenho quanto à melhoria da retenção e espalhamento para melhor cobertura das superfícies. Sugere-se ainda o levantamento de patentes existentes, bem como de material não compilado, incluindo produtos novos e do passado para criação de banco de dados. Um dos grandes usos dos siliconados tem sido com glifosato, visando reduzir perdas por lavagem e melhoria da eficácia. Para tanto, foi feito um ensaio sob condições controladas em casa de vegetação, na Universidade de São Paulo, com objetivo de avaliar o efeito da aplicação de surfactante organossiliconado juntamente com glifosato sob condições de chuva simulada. Utilizou-se a espécie Brachiaria decumbens, cultivada em vasos. Aplicações foram realizadas quando as plantas apresentavam um perfilho de cerca de 30 cm, 30 dias após a semeadura. Os experimentos conduzidos em delineamento inteiramente casualizado em esquema fatorial, sendo cinco doses de glifosato (0, 135, 270, 540 e 1080 g.ha-1 do i.a.) e três doses do organossiliconado Break Thru &reg; (0, 50 e 100 mL.ha-1), com três repetições cada tratamento. Foram conduzidos dois experimentos sem e com chuva simulada de 10 mm, 30 minutos após a aplicação dos tratamentos, sendo as avaliações (controle das plantas daninhas, índice Spad, peroxidação lipídica e massa seca) efetuadas aos 7 e 21 dias após a aplicação dos tratamentos. Observou-se o aumento do percentual de controle e redução no teor de clorofila na dose de 135 g.ha-1 de glifosato com 100 mL.ha-1 do surfactante com chuva simulada. / Nowadays, the Brazilian adjuvant market is approximately 400 million dollars. The most part are oils, that demonstrating low knowledge about organosilicone adjuvants. It was made an extensive literature revision in the Internet, Associations, Private companies, as well specialist opinion. Conclusions were that due to favorable toxicological and environmental characteristics, organosilicone adjuvant can be used with herbicides, fungicides, insecticides, growth regulators, foliar fertilizers and biopesticides. The benefits are improved efficacy of products. The improvement can result from enhanced penetration, uptake, retention or covering of active ingredients. Organosilicones are unique adjuvants in that they can produce stomatal flooding. There are different adjuvant organosilicone. To obtain better results is important taking in consideration: (i) environment conditions, (ii) vegetal species, (iii) application system, (iv) crop management, (iv) active ingredient and (v) target. The creation of simple and clear /regulatory rules for adjuvants in Brazil is needed, using the existent normatization in the USA as reference. According discussions in the Workshop about Adjuvants in the Agriculture in Brazil, promoted by Ministry of Agriculture, Livestock and Supply, the adjuvant must be treated as a chemical product, which will be combined with the existed agrochemicals products in the market. In relation of Research demands, suggesting study the different organosilicone products in relation the properties. As well the possibilities of new personalized combinations that supplying better performance in relation retention improvement and spreading to better surface covering. Suggesting to review all the existed intellectual properties, as well not compiled materials including new products and from past for creating of database. One of big uses of organosilicone had with glyphosate, for reducing wash off losses and efficacy improvement. However, it was carried a trial under controlled conditions in greenhouse, in the University of São Paulo, with objective of evaluate the application of organosilicone surfactant with glyphosate under conditions of simulated rain. The Brachiaria decumbens specie was cultivated in pots. Applications were made when the plants were one tiller of about 30 cm, 30 days after seeding. The experiments were carried out in randomized design, using a factorial scheme, five doses of glyphosate (0, 135, 270, 540 and 1080 g.ha-1 of a.i.), and three doses of silicone adjuvant Break Thru&reg; (0, 50 and 100 mL.ha-1) with three replications for each treatment. Two experiments have been conducted without and with simulated rainfall of 10 mm, 30 minutes after application of the treatments. Seven and 21 days after treatment application the percentage of weed control, Spad index, lipid peroxidation and dry matter were evaluated. This effect was more dramatic in dose of 135 g.ha-1, as well as decreased Spad value, dry matter and lipid peroxidation increase, when associated with a dose of 100 mL.ha-1 surfactant.

Pour étudier le rôle de la mitochondrie dans la tolérance à la sécheresse, la réponse à la contrainte hydrique a été comparée entre une lignée sauvage (WT) et un mutant CMSII (Cytoplasmic Male Sterile) de Nicotiana sylvestris. Chez le mutant CMSII, le complexe I mitochondrial est absent et la respiration est assurée par les NAD(P)H déshydrogénases alternes et elle est maintenue à un niveau supérieur de l’ordre de 20 à 30% à celui du WT. La différence observée entre les plantes WT et CMSII met en jeu non seulement le fonctionnement mitochondrial, mais également le fonctionnement des chloroplastes. En effet, l’activité photosynthétique du mutant est plus faible que celui du WT et elle est corrélée avec une plus faible conductance stomatique (gs) et mésophyllienne (gm).Après l’arrêt de l’arrosage, on observe que le contenu relatif en eau (RWC) diminue plus lentement chez les feuilles du CMSII. Ceci n’était pas le résultat d’une plus petite surface de transpiration ou d’une masse racinaire d’absorption plus élevé puisque le rapport partie aérienne/racine et la surface foliaire totale ont été similaires au début de l’expérience chez les deux génotypes. De plus la mutation n’a pas induit des changements au niveau des paramètres hydriques (P0, PTLP, RWCTLP) ni au niveau de la densité stomatique. La tolérance des plantes CMSII a été le plus probablement la conséquence de sa plus faible transpiration en conditions bien hydratées et aux premiers jours de déshydratation et non pas d’une meilleure efficacité d’absorption de l’eau puisque le contenu en eau du sol reste plus élevé chez CMSII après l’arrêt de l’arrosage. La plus faible conductance stomatique chez le CMSII bien hydraté a été expliquée par sa plus faible conductance hydraulique. De plus, contrairement au WT, le niveau des acides aminés totaux diminue au cours de la déshydratation lorsque le contenu en protéines solubles augmente chez les feuilles du CMSII, suggérant une accélération de la remobilisation des acides aminés. D’autre part, il a été aussi montré que le mutant CMSII est capable de s’acclimater mieux à la sécheresse que le WT lorsqu’ils ont été maintenus à un RWC de 80 % sur plusieurs jours. Sous ces conditions, la photosynthèse reste plus élevée chez le mutant que chez le WT. Cette meilleure acclimatation corrèle avec une plus forte photorespiration du CMSII sous conditions bien hydratées et sous conditions d’acclimatation. La photorespiration chez CMSII et le WT a été estimée par le transport électronique dévolu à l’oxygénation de RuBP et en plus par l’accumulation des métabolites impliqués dans la photorespiration. D’une part, l’acclimatation à la sécheresse diminue gm plus fortement chez le WT que chez le CMSII. D’autre part, le WT accumule la glycine ce qui laisse supposer que le glycine décarboxylase mitochondrial est plus affectée chez le WT que chez le CMS et inhibe ainsi la photorespiration. En effet, cette plus faible photorespiration chez le WT affecte les réactions primaires de la photosynthèse par une accumulation d’un gradient de protons estimé par le quenching non-photochimique (NPQ) de la fluorescence chlorophyllienne ce qui induit une diminution du transport électronique des réactions primaires de la photosynthèse. / To investigate the role of mitochondria in drought stress, the response to water deprivation was compared between Nicotiana sylvestris wild type (WT) plants and the CMSII respiratory complex I mutant. In CMSII, alternative NAD(P)H-dehydrogenases bypassing complex 1 allow respiration.. The difference of mitochondrial function between WT and CMSII plants affect also photosynthesis. The CMSII has lower photosynthetic actitvity than the WT and lower stomatal (gs) and internal (gm) conductances to CO2. When watering of plants with similar leaf surface and similar shoot/root ratio was stopped the relative water content (RWC) declined faster in WT as compared to CMSII leaves. Furthermore, CMSII and WT leaves had the same osmotic potential at leaf saturation (P0) and at leaf turgor lost pressure (PTLP) and the same stomatal density. The slower decline of RWC in CMSII, compared to WT leaves, was most likely the consequence of the lower stomatal conductance (gs) under well-watered conditions and during the first days after withholding watering, The lower stomatal conductance of well-watered CMSII leaves correlated with a lower hydraulic conductance of leaves. Remarkably, total free amino acid levels declined and total soluble protein content increased in CMSII leaves, while the opposite was observed in WT leaves. This suggests protein synthesis in CMSII but protein degradation in WT leaves during drought stress. We also show that CMSII leaves better acclimate to drought stress than the WT leaves. After several days at 80 % RWC , photosynthesis is higher in the mutant than in WT. As compared to the WT, the mutant shows higher rates of photorespiration before and after acclimation to drought.The strong accumulation of glycine in the WT suggests that photorespiration may be limited at the level of glycine decarboxylase. In addition, after acclimation to drought gm declined markedly in WT but not in CMSII leaves, thus further limiting CO2 supply for photosynthesis in the WT. The resulting lower photosynthesis and photorespiration in WT leaves affect also the primary reaction of photosynthesis by increasing the non-photochemical fluorescence quenching (NPQ) and decreasing linear electron transport.

Atualmente, o mercado no Brasil de adjuvantes é de aproximadamente 400 milhões de dólares, sendo que a maior parte são os óleos, o que demonstra o pouco conhecimento sobre o uso de adjuvante organossiliconado. Foi realizada extensa revisão de literatura na Internet, Associações, Empresas privadas, bem como opinião de Especialistas. Pode-se concluir que os organossiliconados podem ser usados para herbicidas, fungicidas, inseticidas, reguladores vegetais, fertilizantes foliares e biopesticidas, devido às características toxicológicas e ambientais favoráveis, bem como os benefícios de melhoria da ação dos produtos, destacando-se a melhor performance em termos de penetração, absorção, retenção e cobertura de ingrediente ativo devido ao conceito de fluidez estomatal e penetração cuticular, que pode permitir redução do volume de água evitando a perda por escorrimento e permitindo melhor eficiência no manejo de problemas fitossanitários. Os adjuvantes organossiliconados não são iguais. Para se obter melhores resultados, é importante considerar: (i) as condições ambientais, (ii) as espécies vegetais, (iii) os sistemas de aplicação, (iv) o sistema de cultivo como um todo, (iv) os ingredientes ativos e (v) o alvo. A criação de uma regulamentação clara e simples é necessária, utilizando a normatização existente nos Estados Unidos como referência. Conforme discutido no Workshop sobre Adjuvantes Agrícolas no Brasil, promovido pelo Ministério da Agricultura, Pecuária e Abastecimento, o adjuvante deve ser tratado como um produto químico, o qual estará sendo combinado com os produtos agroquímicos existentes no mercado. Quanto às demandas de pesquisa, sugere-se estudar os diferentes adjuvantes organossiliconados com relação às suas propriedades, bem como as possibilidades de novas combinações personalizadas que forneçam o melhor desempenho quanto à melhoria da retenção e espalhamento para melhor cobertura das superfícies. Sugere-se ainda o levantamento de patentes existentes, bem como de material não compilado, incluindo produtos novos e do passado para criação de banco de dados. Um dos grandes usos dos siliconados tem sido com glifosato, visando reduzir perdas por lavagem e melhoria da eficácia. Para tanto, foi feito um ensaio sob condições controladas em casa de vegetação, na Universidade de São Paulo, com objetivo de avaliar o efeito da aplicação de surfactante organossiliconado juntamente com glifosato sob condições de chuva simulada. Utilizou-se a espécie Brachiaria decumbens, cultivada em vasos. Aplicações foram realizadas quando as plantas apresentavam um perfilho de cerca de 30 cm, 30 dias após a semeadura. Os experimentos conduzidos em delineamento inteiramente casualizado em esquema fatorial, sendo cinco doses de glifosato (0, 135, 270, 540 e 1080 g.ha-1 do i.a.) e três doses do organossiliconado Break Thru &reg; (0, 50 e 100 mL.ha-1), com três repetições cada tratamento. Foram conduzidos dois experimentos sem e com chuva simulada de 10 mm, 30 minutos após a aplicação dos tratamentos, sendo as avaliações (controle das plantas daninhas, índice Spad, peroxidação lipídica e massa seca) efetuadas aos 7 e 21 dias após a aplicação dos tratamentos. Observou-se o aumento do percentual de controle e redução no teor de clorofila na dose de 135 g.ha-1 de glifosato com 100 mL.ha-1 do surfactante com chuva simulada. / Nowadays, the Brazilian adjuvant market is approximately 400 million dollars. The most part are oils, that demonstrating low knowledge about organosilicone adjuvants. It was made an extensive literature revision in the Internet, Associations, Private companies, as well specialist opinion. Conclusions were that due to favorable toxicological and environmental characteristics, organosilicone adjuvant can be used with herbicides, fungicides, insecticides, growth regulators, foliar fertilizers and biopesticides. The benefits are improved efficacy of products. The improvement can result from enhanced penetration, uptake, retention or covering of active ingredients. Organosilicones are unique adjuvants in that they can produce stomatal flooding. There are different adjuvant organosilicone. To obtain better results is important taking in consideration: (i) environment conditions, (ii) vegetal species, (iii) application system, (iv) crop management, (iv) active ingredient and (v) target. The creation of simple and clear /regulatory rules for adjuvants in Brazil is needed, using the existent normatization in the USA as reference. According discussions in the Workshop about Adjuvants in the Agriculture in Brazil, promoted by Ministry of Agriculture, Livestock and Supply, the adjuvant must be treated as a chemical product, which will be combined with the existed agrochemicals products in the market. In relation of Research demands, suggesting study the different organosilicone products in relation the properties. As well the possibilities of new personalized combinations that supplying better performance in relation retention improvement and spreading to better surface covering. Suggesting to review all the existed intellectual properties, as well not compiled materials including new products and from past for creating of database. One of big uses of organosilicone had with glyphosate, for reducing wash off losses and efficacy improvement. However, it was carried a trial under controlled conditions in greenhouse, in the University of São Paulo, with objective of evaluate the application of organosilicone surfactant with glyphosate under conditions of simulated rain. The Brachiaria decumbens specie was cultivated in pots. Applications were made when the plants were one tiller of about 30 cm, 30 days after seeding. The experiments were carried out in randomized design, using a factorial scheme, five doses of glyphosate (0, 135, 270, 540 and 1080 g.ha-1 of a.i.), and three doses of silicone adjuvant Break Thru&reg; (0, 50 and 100 mL.ha-1) with three replications for each treatment. Two experiments have been conducted without and with simulated rainfall of 10 mm, 30 minutes after application of the treatments. Seven and 21 days after treatment application the percentage of weed control, Spad index, lipid peroxidation and dry matter were evaluated. This effect was more dramatic in dose of 135 g.ha-1, as well as decreased Spad value, dry matter and lipid peroxidation increase, when associated with a dose of 100 mL.ha-1 surfactant.