Roles of glycine betaine and proline in improving plant abiotic stress resistance

Salt tolerance and salinity effects on plants: a review.

Developments in nanotechnology are leading to a rapid proliferation of new materials that are likely to become a source of engineered nanoparticles (ENPs) to the environment, where their possible ecotoxicological impacts remain unknown. The surface properties of ENPs are of essential importance for their aggregation behavior, and thus for their mobility in aquatic and terrestrial systems and for their interactions with algae, plants and, fungi. Interactions of ENPs with natural organic matter have to be considered as well, as those will alter the ENPs aggregation behavior in surface waters or in soils. Cells of plants, algae, and fungi possess cell walls that constitute a primary site for interaction and a barrier for the entrance of ENPs. Mechanisms allowing ENPs to pass through cell walls and membranes are as yet poorly understood. Inside cells, ENPs might directly provoke alterations of membranes and other cell structures and molecules, as well as protective mechanisms. Indirect effects of ENPs depend on their chemical and physical properties and may include physical restraints (clogging effects), solubilization of toxic ENP compounds, or production of reactive oxygen species. Many questions regarding the bioavailability of ENPs, their uptake by algae, plants, and fungi and the toxicity mechanisms remain to be elucidated.

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Environmental behavior and ecotoxicity of engineered nanoparticles to algae, plants, and fungi

Nanoparticulate material delivery to plants

Photosynthesis and activity of superoxide dismutase, peroxidase and glutathione reductase in cotton under salt stress

Plantas de feijoeiro ( Phaseolus vulgarls L) cultivadas em condicoes de campo foram submetidas a quatro regimes de irrigacao, com o proposito de estabelecer uma relacao entre as variacoes da temperatura da copa medida com termometro a infravermelho com a produtividade da cultura, visando introduzir a termometria ao infravermelho no monitoramento da irrigacao Os efeitos dos diferentes regimes de irrigacao foram avaliados mediante as variacoes do acumulo de materia seca, indice de area foliar, taxa de acumulo de materia seca e variacao nos componentes da producao e a produtividade Os menores valores referentes aos parâmetros de crescimento corresponderam as plantas mantidas em menor frequencia de irrigacao, que apresentaram, entre turnos de rega, os maiores valores de temperatura de copa Os decrescimos nos componentes da producao e produtividade tambem foram maiores nas plantas sob estresse mais acentuado Os resultados indicaram que a temperatura da copa mostrou um relacionamento estreito com os componentes da producao e a produtividade, bem como a evolucao do estresse hidrico Isto podera permitir um melhor aproveitamento da termometria ao infravermelho no controle da irrigacao

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Aplicacao da Termometria ao Infravermelho a Irrigacao do Feijoeiro: Crescimento e Produtividade.

Development and assimilate partitioning were studied in Glycine max (L.) Merr. cv. UFV-2 under tour light levels (30, 50, 70 and 100% of sunlight) in field conditions. Irrespective of light flux densities, the maximum number of leaves and maximum height of the plants were attained at the onset of grain filling. Stem elongation increased and the number of leaves and pods were reduced by decreasing light levels. Shading altered the assimilate partitioning among parts but did not change the sequential order of the preferential sinks. The dry matter rates of each organ increased as the light flux densities increased. The rates of root dry matter were more affected by shading than the rates of dry matter production of the other organs.

Desenvolvimento e partição de assimilados em Glycine max crescida sob quatro densidades do fluxo radiante

Seasonal and diurnal changes on pH and mineral compositionof tomato xylem sap Mineral composition and pH seasonal and diurnal changes ofxylem sap were measured in tomato plants, 40 days old, cultivatedin nutritive solution under green house conditions in order to evaluatethe factors that can regulate it. On a first experiment, the sap wasobtained from different plants, same age, always at 9:0 AM, duringselected months. On a second experiment, the sap was obtainedtrough the day, at different times, in a single plant. On the thirdexperiment, the xylem sap was collected from two different positionsin the plant body, at 5 cm up from the soil surface, and at the base ofthe 5 th leaf petiole. The pH and Ca +2 , K + , Mg +2 , NH +4 , NO -3 , PO -34 and SO -4 from the collected saps were analyzed. The pH varied from5.3 to 6.4 during the seasonal experiment period. The pH above 6.0was verified on the months with higher mean temperatures and thepH of 5.4 occurred during the colder months. Potassium and nitratewere the ions found in higher concentrations in the sap. On the diurnalchanges experiment, higher values of nitrate, cation/anion ratio andpH were found during the afternoon readings. On the seasonalexperiment the nitrate concentration and cation/anion ratio of thesap were higher during the months with lower mean temperaturesand lower pH values. The pH of the sap exudates from the stem at 5cm above the soil surface showed a less acid value (pH 6.13) thanthe sap collected from the petiole base (pH 5.64). The results obtainedsuggest that the factors regulating the sap pH affect in different waysthe seasonal and diurnal variations of the pH and mineralconcentration in tomato plants.

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Variação diurna e sazonal do pH e composição mineral da seiva do xilema em tomateiro

Stomatal control of transpiration in the canopy of a clonal

Plantas de Seringueira (Hevea spp.) oriundas dos clones IAN 717, IAN 873, IAN 2903, IAN 3087, IAN 6323 e Fx 3899 foram cultivadas em casa de vegetacao e submetidas a deficits hidricos crescentes no solo com objetivo de avaliar comparativamente os seus efeitos sobre o potencial hidrico foliar, resistencia estomatica, fotossintese, transpiracao e teor de clorofila. Os resultados mostraram que o decrescimo do potencial hidrico no solo reduziram linear e diferentemente o potencial hidrico foliar de todos os clones. Os maiores decrescimos foram encontrados nos clones IAN 717, IAN 3087 e IAN 873 e o menor no IAN 6323. Potenciais hidricos foliares entre -1,6 e -2,0 MPa causaram em todos os clones um rapido aumento da resistencia estomatica e as maiores reducoes da transpiracao corresponderam ao clone IAN 6323. O ponto de compensacao hidrico mais alto foi -2,35 MPa em IAN 2903 e Fx 3899 e o mais baixo -3,18 MPa de IAN 6323. O clone IAN 6323 apresentou um eficiente mecanismo de prevencao a seca e uma efetiva estabilidade do aparelho fotossintetico sob condicoes de estresse. Os clones IAN 717 e IAN 3087 foram, num nivel inferior, tambem resistentes.

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Marco Antonio Oliva

Papers

Aplicacao da Termometria ao Infravermelho a Irrigacao do Feijoeiro: Crescimento e Produtividade.

Desenvolvimento e partição de assimilados em Glycine max crescida sob quatro densidades do fluxo radiante

Variação diurna e sazonal do pH e composição mineral da seiva do xilema em tomateiro

Stomatal control of transpiration in the canopy of a clonal

Resistência à seca em seringueira 1. Balanço hídrico e produção primária em seis clones submetidos a déficit