The opening and closing of stomata are controlled by the integration of environmental and endogenous signals. Here, we show the effects of combining elevated atmospheric carbon dioxide concentration ( eCO 2 ; 600 μmol mol -1 ) and warming (+2°C) on stomatal properties and their consequence to plant function in a Stylosanthes capitata Vogel (C 3 ) tropical pasture. The eCO 2 treatment alone reduced stomatal density, stomatal index, and stomatal conductance ( g s ), resulting in reduced transpiration, increased leaf temperature, and leading to maintenance of soil moisture during the growing season. Increased CO 2 concentration inside leaves stimulated photosynthesis, starch content levels, water use efficiency, and PSII photochemistry. Under warming, plants developed leaves with smaller stomata on both leaf surfaces; however, we did not see effects of warming on stomatal conductance, transpiration, or leaf water status. Warming alone enhanced PSII photochemistry and photosynthesis, and likely starch exports from chloroplasts. Under the combination of warming and eCO 2 , leaf temperature was higher than that of leaves from the warming or eCO 2 treatments. Thus, warming counterbalanced the effects of CO 2 on transpiration and soil water content but not on stomatal functioning, which was independent of temperature treatment. Under warming, and in combination with eCO 2 , leaves also produced more carotenoids and a more efficient heat and fluorescence dissipation. Our combined results suggest that control on stomatal opening under eCO 2 was not changed by a warmer environment; however, their combination significantly improved whole-plant functioning.

Changes in leaf anatomy and ultrastructure are associated with physiological performance in the context of plant adaptations to climate change. In this study, we investigated the isolated and combined effects of elevated atmospheric CO 2 concentration ([CO 2 ]) up to 600 μmol mol -1 ( eC ) and elevated temperature ( eT ) to 2°C more than the ambient canopy temperature on the ultrastructure, leaf anatomy, and physiology of Panicum maximum Jacq. grown under field conditions using combined free-air carbon dioxide enrichment (FACE) and temperature free-air controlled enhancement (T-FACE) systems. Plants grown under eC showed reduced stomatal density, stomatal index, stomatal conductance ( g s ), and leaf transpiration rate ( E ), increased soil-water content ( SWC ) conservation and adaxial epidermis thickness were also observed. The net photosynthesis rate ( A ) and intrinsic water-use efficiency ( iWUE ) were enhanced by 25% and 71%, respectively, with a concomitant increase in the size of starch grains in bundle sheath cells. Under air warming, we observed an increase in the thickness of the adaxial cuticle and a decrease in the leaf thickness, size of vascular bundles and bulliform cells, and starch content. Under eCeT , air warming offset the eC effects on SWC and E , and no interactions between [CO 2 ] and temperature for leaf anatomy were observed. Elevated [CO 2 ] exerted more effects on external characteristics, such as the epidermis anatomy and leaf gas exchange, while air warming affected mainly the leaf structure. We conclude that differential anatomical and physiological adjustments contributed to the acclimation of P . maximum growing under elevated [CO 2 ] and air warming, improving the leaf biomass production under these conditions.

Global warming is predicted to cause more intense extreme events such as heat waves, flooding and severe droughts, producing significant effects on agriculture. In tropics, climate change will severely impact livestock production affecting water availability, forage quality and food for cattle. We investigated the isolated and combined effects of soil water deficit (wS) and + 2°C increase in canopy temperature (eT) on leaf gas exchange, chlorophyll fluorescence, carbohydrate content, forage quality and in vitro dry matter digestibility (IVDMD) of a field‐grown C4 tropical forage grass Panicum maximum Jacq. using a temperature‐free air‐controlled enhancement (T‐FACE) system. The wS and eT treatments showed no effects on photosystem II photochemistry. However, wS under ambient temperature decreased net photosynthesis rate (A), stomatal conductance (gs) and maximum rate of carboxylation of Rubisco (Vcmax), leading to a reduced starch content in leaves. A 16% reduction in leaf dry mass (LDM) and reduction in forage quality by increasing fibers, reducing crude protein (CP) and decreasing the IVDMD was also observed by effect of wS. Warming under adequate soil moisture (eT) significantly increased LDM by 25% but reduced the forage quality, increasing the lignin content and reducing starch, CP and digestibility. The combined wSeT treatment reduced A, gs, Vcmax and the forage quality. When compared to control, the lignin content in leaves increased by 43, 28 and 17% in wS, eT and wSeT, respectively, causing a significant reduction in IVDMD. We concluded that despite physiological mechanisms to acclimate to warming, both warming and water deficit will impair the quality and digestibility of C4 tropical pastures.

No abstract

RESUMOPara avaliar, na Região Noroeste do Estado de São Paulo, o desenvolvimento em fase de viveiro do açaizeiro da cultivar de terra firme Pará, foram monitoradas as respostas do crescimento e da taxa fotossintética, quando submetido a tratamentos de atenuação de 16% e 50% da radiação solar global, até a idade de 8 meses. A altura da planta e o diâmetro do caule, assim como a acumulação de matéria seca, não foram influenciados pelos tratamentos (p< 0,05). Porém, em plantas crescendo sob baixa atenuação de irradiância, os valores de área foliar foram significativamente inferiores a partir dos 5 meses, e da taxa fotossintética líquida e da irradiância de saturação, após os 6 meses (p< 0,05). Os resultados indicam potencial para a produção de mudas nesta região paulista, sobretudo quando mantidas sob atenuação de 50% da irradiância.Palavras-chave: área foliar, taxa fotossintética líquida, irradiância de saturação, sombreamento. ABSTRACT NURSERY DEVELOPMENT OF NON-FLOODED AÇAI PALM (EUTERPE OLERACEAE, MART, PARÁ CULTIVAR) UNDER ATTENUATION OF SOLAR RADIATIONIn the northwest region of São Paulo State, Brazil was investigated the outcomes of the plant growth and photosynthetic rate of a açai palm cultivar Para (PA), under attenuation of total radiation in 16% and 50% until the age of 8 months. The plant height, the stem diameter and the dry matter accumulation were not influenced by the treatments (p<0.05). However, plants growing under lower attenuation of irradiance started to show significant lower values of leaf area in 5 months; and rate of net photosynthesis and irradiance saturation after 6 months (p<0.05). These results indicated that the seedlings has a potential to adapt in this region, since maintained under attenuation of 50% of irradiance.

No abstract

Perennial grasses, such as Panicum maximum, are important alternatives to dedicated energy crops for bioethanol production. This study investigates whether future climate conditions could influence P. maximum cell-wall structure and hydrolytic performance. To analyze interactions with environmental factors in field conditions, a combined Free-air Temperature and CO 2 Controlled Enhancement (Trop-T-FACE) facility was used to investigate the isolated and combined effect of elevated atmospheric CO 2 concentration (eC) (600 μmol.mol −1 ) and elevated temperature (eT) by 2 °C more than the ambient temperature, on cell-wall composition, cellulose crystallinity, accessibility, and hydrolysis yields. The elevated temperature treatments (eT and eT + eC) exhibited the most pronounced effects on the P. maximum cell wall. Warming reduced the starch content and the crystallinity index (CI) of cellulose and increased the cellulose content. Fluorescent protein-tagged carbohydrate-binding modules analysis demonstrated that warming improved total cellulose surface exposure/accessibility in eT and eT + eC

RESUMOAs praças públicas servem como escape para as pessoas que desejam um pouco de natureza no seu dia a dia, pois é um ambiente que propicia elementos naturais aos cidadãos, trazendo harmonia e bem-estar, sendo uma área de lazer, tendo importância em aspectos ecológicos, sociais e políticos contribuindo na preservação da flora. Teve como objetivo realizar o levantamento de espécies vegetais nas praças públicas de Humaitá-AM. Foram visitados cinco bairros com cinco praças, sendo uma praça em cada bairro que são; Praça da Matriz, Praça da Saúde, Praça da Rodoviária, Praça Santo Antônio e Praça da Olaria. A identificação das espécies foi realizada por meio de levantamento de campo e confirmada com auxílio de identificadores botânicos e da literatura científica. As espécies mais encontradas foram da família Arecaceae; areca bambu com dezessete espécimes (Dypsis lutescens (H. Wendl.) Beentje & J.) e palmeira azul com dezessete espécimes (Bismarckia nobilis Hildebr. & H. Wendl.); da família Moraceae, figueira-benjamim com quarenta e oito espécimes (Ficus benjamina L.); da família Myrtaceae, jambo vermelho com quarenta espécimes (Syzygium malaccense (L.) Merr. & L.M. Perry); da família Chrysobalanaceae; oiti com quinze espécimes (Licania tomentosa (Benth.) Fritsch.); da família Rubiaceae, ixora compacta com onze espécimes (Ixora coccinea L.) e família Anacardiaceae, manguá com 13 espécimes (Mangifera indica L.). Portanto as praças são importantes para o lazer e bem-estar, pois serve para as pessoas perceberem que a natureza faz parte da vida humana e é essencial viver em equilíbrio com a mesma. Palavras-chaves: Espécies Vegetais, Equilíbrio e Myrtaceae.