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Este estudo teve por objetivo gerar um diagnóstico da percepção dos moradores em relação à arborização em um conjunto habitacional em Paragominas, Pará. A metodologia utilizada baseou-se na aplicação de questionários com perguntas objetivas e subjetivas. A aplicação dos questionários foi realizada por meio de amostragem aleatória, baseada na estatística de 10% do número de residências, totalizando 110 entrevistados. Os resultados demonstram que a população necessita de espaços mais arborizados, os quais irão proporcionar maior conforto térmico, sendo relatado como os maiores benefícios a sombra e redução de calor, com 48% e 42%, respectivamente. 8% dos entrevistados consideram que a arborização possui desvantagens, sendo relatada a sujeira nas calçadas, causada principalmente pelas folhas e frutos como a principal. A maioria dos moradores mostraram interesse em participar de projetos de arborização e ressaltaram a necessidade de programas de educação ambiental, principalmente para o cuidado com as mudas. Os moradores escolheram como principal espécie a ser plantada o ipê (Handroanthus spp. Mattos), devido a suas flores vistosas e coloridas. Os moradores mostraram ser conscientes que a prefeitura é a responsável por projetos de arborização, bem como que o vandalismo é uma das causas que mais prejudica a falta de árvores no conjunto.

& Key message Our research revealed that 24-epibrassinolide alleviated nickel toxicity in young Eucalyptus urophylla plants, inducing benefits on nutritional, physiological, biochemical, anatomical and morphological responses. & Context Soil contamination by heavy metals may limit the Eucalyptus production. Disturbances caused by nickel (Ni) toxicity interfere with the absorption of other essential nutrients. 24-Epibrassinolide (EBR) is one form of brassinosteroid (BR) that provides benefits for plant metabolism under Ni toxicity. & Aims The aim of this study was to determine whether exogenous EBR can improve ionic homeostasis by evaluating nutrient concentrations, anatomical characteristics and chlorophyll fluorescence in young Eucalyptus urophylla plants subjected to Ni toxicity. & Methods The experiment was randomized into four treatments, including two Ni concentrations (0 and 600 μM Ni) and two 24epibrassinolide concentrations (0 and 100 nM EBR). & Results EBR significantly reduced Ni contents. Plants exposed to Ni 2+ and sprayed with steroid had increases in the Ca 2+ /Ni 2+ and Mn 2+ /Ni 2+ ratios in the leaves of 38% and 15%, respectively, compared with the same treatment without EBR. The treatment of Ni 2+ toxicity + EBR presented an increase of 42% in effective quantum yield of PSII photochemistry, when compared with plants exposed to Ni without EBR. Ni toxicity induced negative effects on stomatal functionality, but EBR application mitigated these effects. & Conclusion Benefits on effective quantum yield of PSII photochemistry after EBR spray can be related to increases in manganese contents. EBR reduced oxidative stress, alleviating the deleterious effects induced by Ni toxicity and inducing positive repercussions on antioxidant enzymes, photosynthetic pigments and biomass.

Cadmium (Cd2+) soil pollution is a global environmental problem caused by the high toxicity of Cd. 24‐Epibrassinolide (EBR) is a biodegradable plant steroid involved in response modulation to biotic and abiotic stresses. The aim of this study was to evaluate if the leaf‐application of EBR improves the gas exchange and possible repercussions on leaf anatomy in young Eucalyptus urophylla plants exposed to Cd toxicity. The experiment involved six treatments, which included three Cd concentrations (0, 450, and 900 μM) and two EBR concentrations (0 and 100 nM, described as – EBR and + EBR, respectively). Plants exposed to Cd toxicity suffered decreases in leaf anatomical and gas exchange parameters. However, the plants treated with EBR + 900 μM Cd showed an increase of 46%, 40%, and 54% in the net photosynthetic rate, water‐use efficiency, and instantaneous carboxylation efficiency, respectively. The EBR application‐induced improvements in gas exchange parameters, causing beneficial effects on the photosynthetic apparatus, mainly the effective quantum yield of photosystem II (PSII) photochemistry and electron transport rate. Furthermore, this steroid mitigated the effect of Cd toxicity on leaf anatomical variables, more specifically palisade and spongy parenchyma, which are intrinsically related to stomatal density, and stimulated the net photosynthetic rate of plants.