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Despite being evolved in shaded environments, most coffee (Coffea arabica L.) is cultivated worldwide under sparse shade or at full sunlight. Coffee is ranked as greatly responsive to climate change (CC), and shading has been considered an important management strategy for mitigating the harmful CC outcomes on the crop. However, there is no information on the effects of enhanced [CO2] (eCa) on coffee performance in response to light availability. Here, we examined how carbon assimilation and use are affected by eCa in combination with contrasting light levels. For that, greenhouse-grown plants were submitted to varying light levels (16 or 7.5 mol photons m−2 day−1) and [CO2] (ca. 380 or 740 μmol mol−1 air) over six months. We demonstrated that both high light and eCa improved growth and photosynthetic performance, independently. Despite marginal alterations in biomass partitioning, some allometric changes, such as higher root biomass-to-total leaf area and lower leaf area ratio under the combination of eCa and high light were found. Stimulation of photosynthetic rates by eCa occurred with no direct effect on stomatal and mesophyll conductances, and no signs of photosynthetic down-regulation were found irrespective of treatments. Particularly at high light, eCa led to decreases in both photorespiration rates and oxidative pressure. Overall, our novel findings suggest that eCa could tandemly act with shading to mitigate the harmful CC effects on coffee sustainability.

The overall coordination between gas exchanges and plant hydraulics may be affected by soil water availability and source-to-sink relationships. Here we evaluated how branch growth and mortality, leaf gas exchange and metabolism are affected in coffee (Coffea arabica L.) trees by drought and fruiting. Field-grown plants were irrigated or not, and maintained with full or no fruit load. Under mild water deficit, irrigation per se did not significantly impact growth but markedly reduced branch mortality in fruiting trees, despite similar leaf assimilate pools and water status. Fruiting increased net photosynthetic rate in parallel with an enhanced stomatal conductance, particularly in irrigated plants. Mesophyll conductance and maximum RuBisCO carboxylation rate remained unchanged across treatments. The increased stomatal conductance in fruiting trees over nonfruiting ones was unrelated to internal CO2 concentration, foliar abscisic acid (ABA) levels or differential ABA sensitivity. However, stomatal conductance was associated with higher stomatal density, lower stomatal sensitivity to vapor pressure deficit, and higher leaf hydraulic conductance and capacitance. Increased leaf transpiration rate in fruiting trees was supported by coordinated alterations in plant hydraulics, which explained the maintenance of plant water status. Finally, by preventing branch mortality, irrigation can mitigate biennial production fluctuations and improve the sustainability of coffee plantations. Universidad Federal de Viçosa, Brasl. Universidad Nacional, Costa Rica. Escuela de Ciencias Biológicas

Iron (Fe) toxicity is often observed in lowland rice (Oryza sativa L.) plants, disrupting cell homeostasis and impairing growth and crop yields. Silicon (Si) can mitigate the effects of Fe excess on rice by decreasing tissue Fe concentrations, but no information exists whether Si could prevent the harmful effects of Fe toxicity on the photosynthesis and carbon metabolism. Two rice cultivars with contrasting abilities to tolerate Fe excess were hydroponically grown under two Fe levels (25 μM or 5 mM) and amended or not with Si (0 or 2 mM). Fe toxicity caused decreases in net photosynthetic rate (A), particularly in the sensitive cultivar. These decreases were correlated with reductions in stomatal (gs) and mesophyll (gm) conductances, as well as with increasing photorespiration. Photochemical (e.g. electron transport rate) and biochemical (e.g., maximum RuBisCO carboxylation capacity and RuBisCO activity) parameters of photosynthesis, and activities of a range of carbon metabolism enzymes, were minimally, if at all, affected by the treatments. Si attenuated the decreases in A by presumably reducing the Fe content. In fact, A as well as gs and gm, correlated significantly with leaf Fe contents. In summary, our data suggest a remarkable metabolic homeostasis under Fe toxicity, and that Si attenuated the impairments of Fe excess on the photosynthetic apparatus by affecting the leaf diffusive conductance with minimal impacts on carbon metabolism.

Rising air CO2 concentration ([CO2]) is believed to mitigate the negative impacts of global climate changes such as increased air temperatures and drought events on plant growth and survival. Nonetheless, how elevated [CO2] affects the way coffee (Coffea arabica L.) plants sense and respond to drought remains a critical unknown. In this study, potted coffee plants were cultivated under two air [CO2] (ca. 400 ppm or 700 ppm) in open top chambers under greenhouse conditions. After a 5-month exposure to [CO2] treatments, plants were submitted to a progressive, controlled soil water deficit down to 20 % soil field capacity. Under well-watered (100 % field capacity) conditions, 700-plants displayed lower whole-plant transpiration rates (T) than their 400-counterparts. Changes in T were unrelated to stomatal conductances at the leaf scale (as well as stomatal morphology) or foliar ABA levels, but they were rather associated with faster stomata closure rates upon rapid increases in vapor pressure deficit in the 700-plants. During drought, 700-plants were able to maintain higher water potentials and plant hydraulic conductances for longer in parallel to higher T than their 400-counterparts. Under elevated [CO2], the faster stomatal closure rates (irrigated conditions) or the maintenance of plant hydraulic conductances (drought conditions) were associated with higher (3 to 40-fold) transcript abundance of most aquaporin genes. Altogether, our results suggest that elevated [CO2] has marked implications on how coffee plants respond to soil water deficit, ultimately permitting 700-plants to have improved fitness under drought when compared to 400-plants.

The environmental factors that affect the morphological characteristics of different genera of cacti are little known. The aim of this study therefore was to analyse the contribution of environmental variables to growth in cladodes and plant of forage cactus clones of the genera Nopalea and Opuntia. The data used in this study were obtained from an experiment conducted in Serra Talhada, Pernambuco, Brazil, between 2012 and 2013, where the clones 'IPA Sertânia' (Nopalea), 'Miúda' (Nopalea) and 'Orelha de Elefante Mexicana' (Opuntia) were submitted to different irrigation depths (2.5, 5.0 and 7.5 mm) and fixed irrigation intervals (7, 14 and 28 days). Morphological characteristics of the cladodes and plants and weather variables were obtained over time. Pearson's correlation, followed by multicollinearity, canonical and path analysis were applied. The minimum temperature, maximum and minimum relative humidity, wind speed and solar radiation were the variables that most affected growth in the cactus. The genus Opuntia showed less sensitivity to variations in air temperature compared to the genus Nopalea. The higher intensities of global solar radiation affected clones of the genus Nopalea more than the genus Opuntia. It can be concluded that there are different environmental requirements between forage cacti of the genera Nopalea and Opuntia. RESUMO Os fatores ambientais que afetam as características morfológicas de distintos gêneros de cactáceas são pouco conhecidos. Assim, objetivou-se analisar a contribuição de variáveis ambientais para o crescimento dos cladódios e da planta de clones de palma forrageira dos gêneros Nopalea e Opuntia. Os dados usados nesse estudo foram adquiridos de um experimento conduzido em Serra Talhada, Pernambuco, entre os anos de 2012 e 2013, onde os clones 'IPA Sertânia' (Nopalea), 'Miúda' (Nopalea) e 'Orelha de Elefante Mexicana' (Opuntia) foram submetidos a distintas lâminas (2,5; 5,0; e 7,5 mm) e intervalos fixos de irrigação (7; 14 e 28 dias). Características morfológicas dos cladódios e das plantas, e variáveis meteorológicas foram obtidas ao longo do tempo. Correlação de Pearson, seguida de análises de multicolinearidade, canônica e trilha foram aplicadas. Temperatura mínima, umidade relativa máxima e mínima, velocidade do vento e radiação solar foram as variáveis que mais afetaram o crescimento da palma. O gênero Opuntia revelou menor sensibilidade à variação da temperatura do ar quando comparado ao gênero Nopalea. As maiores intensidades de radiação solar global afetaram mais os clones do gênero Nopalea do que do gênero Opuntia. Conclui-se que há uma exigência ambiental diferenciada entre os gêneros Nopalea e Opuntia de palma forrageira.

Poucos são os estudos que destacam o efeito de diferentes regimes hídricos sobre o crescimento de plantas da Caatinga; ao passo que modelos matemáticos empíricos são utilizados em larga escala na modelagem de crescimento de plantas, mas também tem sido pouco aplicados para espécies desse bioma. Objetivou-se avaliar o crescimento inicial e o desempenho de modelos matemáticos no ajuste de dados biométricos e de biomassa de espécies ocorrentes na caatinga sob diferentes regimes hídricos. Um experimento foi conduzido, em condições de viveiro, no município de Serra Talhada, PE, com as espécies Caesalpinia pyramidallis Tul. (catingueira) e Prosopis juliflora Sw (DC.) (algaroba) submetidas a regimes hídricos com base na evapotranspiração de referência (ETo) (50%.ETo, 75%.ETo, 100%.ETo e 125%.ETo). Ao longo do tempo foram feitas medições biométricas e de biomassa nas plantas. Foram testados os modelos de Gompertz, Sigmoidal, Logístico, Chapman e Gaussiano, usando como variáveis independentes, os dias após a semeadura e graus dias acumulados. Os quatro regimes hídricos não exerceram influência na matéria seca da raiz, e não se observou diferenças para o acúmulo de matéria seca das folhas e da planta nas lâminas superiores a 75% de ETo. P. juliflora apresentou maior emissão de folíolos, porém não se diferenciou em área foliar da C pyramidalis. As variáveis biométricas da catingueira e da algaroba foram melhores ajustadas pelo modelo de Gompertz, enquanto os de Chapman e Gaussiano foram os que mais explicaram a variação dos dados de biomassa nos distintos regimes hídricos, utilizando como variável independente os graus dias acumulados. A B S T R A C T Few are the studies that highlight the effect of different water regimes on the plants growth of the Caatinga; while empirical mathematical models are used in a large scale in the modelling of plants growth, but it also has been applied to species of this biome. Objective to evaluate the initial growth and performance of mathematical models in the adjustment of biometric and biomass data of species occurring in the caatinga under different water regimes. An experiment was conducted under conditions of viveiro, in the municipality of Serra Talhada, State of Pernmabuco, with the species Caesalpinia pyramidallis Tul. (catingueira) and Prosopis juliflora Sw (DC.) (algaroba) submitted to water regimes based on the reference evapotranspiration (ETo) (50%.ETo, 75%.ETo, 100%.ETo and 125%.ETo). Over time biometric and biomass measurements in plants were made. The Gompertz, Logistic, Sigmoid, Chapman and Gaussian models were tested, using as independent variables, the days after sowing and degrees days accumulated. The four water regimes do not exerted influence on root dry matter, and was not observed differences for dry matter accumulation of leaves and the plant in water regime greater than 75% of ETo. P. juliflora higher issuing leaflets, but not differentiated in leaf area of C. pyramidalis. Biometric variables of C. pyramidalis and P. juliflora were better adjusted by the Gompertz model, while Chapman and Gaussian were more explained the variation of biomass data in the different water regimes using as independent variable the degree days accumulated. Keywords: algaroba, biometrics, biomass, catingueira, degree days, modeling, nonlinear regression.

The increase in the occurrence of extreme weather events in recent decades is a strong evidence of climate change. In semiarid regions, where the pressure of desertification has intensified, are expected to decrease in the availability of water and higher occurrence of drought periods, and, consequently, effects on physiological response of plants. Thus, the objective of analyzing the impacts of climate change scenarios on the duration of phenological cycle and water demand of forage sorghum and cowpea, grown in the State of Pernambuco. Monthly values were used normal climatological solar brightness, air temperature, relative humidity and wind speed of ten municipalities. It was considered an increase of 1.8° C (B2 Scenario) and 4.0° C (A1F1 Scenario) on air temperature and a decrease of 5.0% of the absolute values of relative humidity, in addition to the 22% increase in stomatal resistance and 4% in leaf area index. Based on this information were generated three scenarios: current situation and future projections for B2, A1F1. The results revealed an average reduction of 11% (B2) and 20% (A1F1), and 10% (B2) and 17% (A1F1) for the duration of the cycle, and 4% (B2) and 8% (A1F1), and 2% (B2) and 5% (A1F1) in accumulated water demand for forage sorghum and cowpea, respectively. It is concluded that the magnitude of the reductions in the duration of the cycle and the simulated water demand for crops of forage sorghum and cowpea ranged space-temporarily in the State of Pernambuco with climate change scenarios.

Here we aimed to evaluate the influence of cladode morphology on the canopy formation of forage cactus plants. The study was carried out in Serra Talhada, the State of Pernambuco, using the IPA Sertânia (IPA), Miúda (MIU), and Orelha de Elefante Mexicana (OEM) clones, which were submitted to three irrigation depths (2.5, 5.0, or 7.5 mm) and three irrigation intervals (7, 14, or 28 days) from March 2012 to August 2013. Cladode and plant canopy biometric data were obtained during the experimental period. We found that the characteristics of the second and third order cladodes contributed most to the canopy formation of clones of the genus Nopalea (IPA and MIU), whereas, for the genus Opuntia (OEM), the first and third order cladodes contributed most. Overall, we found that the influence of the cladode variables on the canopy growth of forage cactus is more associated with the characteristics of the genus than to the peculiarities of the clones. RESUMO O objetivo foi avaliar a influência das características morfológicas dos cladódios sobre a formação do dossel da palma forrageira. O estudo foi conduzido em Serra Talhada, PE, com os clones IPA Sertânia - IPA, Miúda - MIU e Orelha de Elefante Mexicana - OEM, os quais foram submetidos a três lâminas (2,5; 5,0; e 7,5 mm) e três intervalos de irrigação (7; 14 e 28 dias), no período compreendido entre março 2012 a agosto de 2013. Dados das dimensões dos cladódios e do dossel das plantas foram obtidos ao longo do tempo. A matriz de correlação de Pearson foi elaborada, e análises canônicas e de trilha foram aplicadas para avaliação da associação entre as variáveis. Verificou-se que, as características dos cladódios de 2ª e de 3ª ordens foram as que mais contribuíram na formação do dossel dos clones do gênero Nopalea (IPA Sertânia e Miúda), enquanto para a Orelha de Elefante Mexicana do gênero Opuntia foram as dos cladódios de primeira 1ª e 3ª ordens. Conclui-se que, a influência das variáveis dos cladódios sobre o crescimento do dossel da palma forrageira esteve mais associada às características do gênero, do que a peculiaridades dos clones.

Poucos sao os estudos que destacam o efeito de diferentes regimes hidricos sobre o crescimento de plantas da Caatinga; ao passo que modelos matematicos empiricos sao utilizados em larga escala na modelagem de crescimento de plantas, mas tambem tem sido pouco aplicados para especies desse bioma. Objetivou-se avaliar o crescimento inicial e o desempenho de modelos matematicos no ajuste de dados biometricos e de biomassa de especies ocorrentes na caatinga sob diferentes regimes hidricos. Um experimento foi conduzido, em condicoes de viveiro, no municipio de Serra Talhada, PE, com as especies Caesalpinia pyramidallis Tul. (catingueira) e Prosopis juliflora Sw (DC.) (algaroba) submetidas a regimes hidricos com base na evapotranspiracao de referencia (ETo) (50%.ETo, 75%.ETo, 100%.ETo e 125%.ETo). Ao longo do tempo foram feitas medicoes biometricas e de biomassa nas plantas. Foram testados os modelos de Gompertz, Sigmoidal, Logistico, Chapman e Gaussiano, usando como variaveis independentes, os dias apos a semeadura e graus dias acumulados. Os quatro regimes hidricos nao exerceram influencia na materia seca da raiz, e nao se observou diferencas para o acumulo de materia seca das folhas e da planta nas lâminas superiores a 75% de ETo. P. juliflora apresentou maior emissao de foliolos, porem nao se diferenciou em area foliar da C pyramidalis. As variaveis biometricas da catingueira e da algaroba foram melhores ajustadas pelo modelo de Gompertz, enquanto os de Chapman e Gaussiano foram os que mais explicaram a variacao dos dados de biomassa nos distintos regimes hidricos, utilizando como variavel independente os graus dias acumulados. A B S T R A C T Few are the studies that highlight the effect of different water regimes on the plants growth of the Caatinga; while empirical mathematical models are used in a large scale in the modelling of plants growth, but it also has been applied to species of this biome. Objective to evaluate the initial growth and performance of mathematical models in the adjustment of biometric and biomass data of species occurring in the caatinga under different water regimes. An experiment was conducted under conditions of viveiro, in the municipality of Serra Talhada, State of Pernmabuco, with the species Caesalpinia pyramidallis Tul. (catingueira) and Prosopis juliflora Sw (DC.) (algaroba) submitted to water regimes based on the reference evapotranspiration (ETo) (50%.ETo, 75%.ETo, 100%.ETo and 125%.ETo). Over time biometric and biomass measurements in plants were made. The Gompertz, Logistic, Sigmoid, Chapman and Gaussian models were tested, using as independent variables, the days after sowing and degrees days accumulated. The four water regimes do not exerted influence on root dry matter, and was not observed differences for dry matter accumulation of leaves and the plant in water regime greater than 75% of ETo. P. juliflora higher issuing leaflets, but not differentiated in leaf area of C. pyramidalis . Biometric variables of C. pyramidalis and P. juliflora were better adjusted by the Gompertz model, while Chapman and Gaussian were more explained the variation of biomass data in the different water regimes using as independent variable the degree days accumulated. Keywords: algaroba, biometrics, biomass, catingueira, degree days, modeling, nonlinear regression.

This study aimed to understand the relationship of morphological characteristics and actual evapotranspiration of forage cactus clones with their productive capacity under different water regimes. The data used in this study were collected between the years 2012 and 2013, in Serra Talhada, State of Pernambuco. The clones Sertânia IPA - IPA, Miúda - MIU and Orelha de Elefante Mexicana - OEM were submitted to three irrigation depths (2.5, 5.0 and 7.5 mm) and three irrigation intervals (7, 14 and 28 days). Cladode and plant morphology, accumulated actual evapotranspiration and yield were obtained at the moment of harvest. Pearson’s correlation matrix was elaborated and, in the sequence, multicollinearity, canonical and path analysis were applied. There was no correlation of yield with the soil water supply and actual evapotranspiration of the clones (p > 0.05). Forage cactus yield was more associated with peculiarities of the morphological characteristics of the clones than with the different soil water supplies or the crop actual evapotranspiration. However, regardless of the water regime and clone, the vigor of the basal cladodes was highly decisive for the expression of the forage cactus productive capacity. RESUMO Objetivou-se, neste trabalho, compreender a relação de características morfológicas e da evapotranspiração real de clones de palma forrageira com sua capacidade produtiva em diferentes regimes hídricos. Os dados usados nesta pesquisa foram coletados entre os anos de 2012 e 2013, em Serra Talhada, PE. Os clones IPA Sertânia - IPA, Miúda - MIU e Orelha de Elefante Mexicana - OEM foram submetidos a três lâminas (2,5; 5,0; e 7,5 mm) e três intervalos de irrigação (7; 14 e 28 dias). Dados morfológicos dos cladódios e da planta, evapotranspiração real acumulada e desempenho produtivo foram obtidos na ocasião da colheita. A matriz de correlação de Pearson foi elaborada e, em seguida, foram aplicadas análises de multicolinearidade, canônica e de trilha. Não houve correlação da produtividade com o suprimento de água e evapotranspiração real dos clones (p > 0,05). A produtividade da palma esteve mais associada a peculiaridades das características morfológicas dos seus clones do que aos diferentes suprimentos de água no solo ou à evapotranspiração real da cultura. Mas, independente do regime hídrico e do clone, o vigor do cladódio basal foi bastante decisivo para a expressão da capacidade produtiva da palma forrageira irrigada.

Embora pertencentes ao mesmo grupo fotossintético (MAC - Metabolismo Ácido das Crassuláceas), a evapotranspiração de distintas espécies de palma forrageira pode responder de maneira diferenciada às variáveis meteorológicas, e depende da sua dinâmica do crescimento. Objetivou-se analisar a contribuição de variáveis meteorológicas e de características morfológicas dos cladódios e da planta sobre a evapotranspiração de espécies de palma forrageira dos gêneros Nopalea e Opuntia. O experimento foi conduzido em Serra Talhada, Pernambuco, onde as espécies ‘IPA Sertânia’ (Nopalea sp.), ‘Miúda’ (Nopalea sp.) e Orelha de Elefante Mexicana (Opuntia sp.) foram submetidos a distintas lâminas (2,5; 5,0; e 7,5 mm) e intervalos e irrigação (7; 14 e 28 dias). A evapotranspiração real e dados biométricos das espécies de palma, e variáveis meteorológicas foram obtidos entre março de 2012 e agosto de 2013. Matriz de correlação de Pearson e análises canônica e de trilha foram aplicadas aos dados. Verificou-se que a radiação solar global se destacou como a variável que mais influenciou na redução da evapotranspiração real (ET) das três espécies, e a velocidade do vento àquela que afetou a resposta da ET à variação da demanda atmosférica (ET/ETo) das espécies Orelha de Elefante Mexicana e ‘IPA Sertânia’. O aumento do índice de área do cladódio implicou na redução da ET dessas duas últimas espécies, enquanto os efeitos do número de cladódios de 1ª e 2ª ordens foram os mais importantes para a ‘Miúda’. Logo, a evapotranspiração da palma forrageira depende da sazonalidade das condições meteorológicas e das características morfológicas das suas espécies. Despite belonging to the same photosynthetic group (CAM - Crassulacean Acid Metabolism), evapotranspiration of distinct species of forage cactus may respond differently to meteorological variables and depends on its growth dynamics. The objective of this work was to analyze the contribution of meteorological variables and morphological characteristics of cladodes and the plants on the evapotranspiration of forage cactus species of the genus Nopalea and Opuntia. The experiment was conducted in Serra Talhada, State of Pernambuco, where the species ‘IPA Sertânia’ (Nopalea sp.), ‘Miúda’ (Nopalea sp.) and ‘Orelha de Elefante Mexicana’ (Opuntia sp.) were submitted to different irrigation depths (2.5, 5.0 and 7.5 mm) and intervals (7, 14 and 28 days). Actual evapotranspiration and biometric data of forage cactus species and meteorological variables were obtained between March 2012 and August 2013. Pearson correlation matrix and canonical and path analysis were applied to the data. It was verified that the global solar radiation stood out as the variable that most influenced the reduction of the actual evapotranspiration (ET) of the three species, and the wind velocity as the one that affected the response of ET to the atmospheric demand variation (ET/ETo) of the species ‘Orelha de Elefante Mexicana’ and ‘IPA Sertânia’. The increase in the cladode area index implied in the reduction of ET of the latter two species, while the effects of the number of 1st and 2nd order cladodes were the most important for the ‘Miúda'. Hence, forage cactus evapotranspiration depends on the seasonality of the meteorological conditions and the morphological characteristics of its species.

Excess iron (Fe) is commonly observed in wetland rice (Oryza sativa L.) plants, impairing crop growth and productivity. Some information suggests that silicon (Si) can reduce Fe content in leaves and roots of rice (vegetative phase), but nothing is known if Si could mitigate the effects of Fe toxicity on rice production and photosynthesis. Here, we assessed the role of Si in alleviating the well-known effects of Fe toxicity on nutritional imbalances, biomass accumulation, photosynthesis and grain yield using two rice cultivars having differential abilities to tolerate excess Fe. Plants were hydroponically grown under two Fe levels (25 μM or 5 mM) and the nutrient solutions were amended with Si (0 or 2 mM). Under excess Fe were detected (i) nutritional deficiencies, especially of calcium and magnesium in leaves; (ii) negligible changes in grain nutritional composition, independently of Si application; (iii) decreases in net photosynthetic rates, stomatal conductance and electron transport rate, in parallel to decreased grain yield components (total grain biomass, 1000-grain mass, percentage of filled grains, number of grains per plant and harvest index), especially in the Fe-sensitive cultivar. These impairments were partially reversed by the application of Si. Results also suggest that Si alleviated the negative impacts of Fe on spikelet sterility. In summary, we conclude that the use of Si can be recommended as an effective management strategy to reduce the negative impacts of Fe toxicity on rice photosynthetic performance and crop yield.

O aumento na ocorrência de eventos climáticos extremos nas últimas décadas é uma forte evidência das mudanças climáticas. Em regiões Semiáridas, onde a pressão de desertificação tem se intensificado, são esperadas diminuição da disponibilidade de água e maior ocorrência de períodos seca, e, consequentemente, efeitos na resposta fisiológica das plantas. Assim, objetivou-se analisar os impactos dos cenários de mudanças climáticas sobre a duração do ciclo fenológico e a demanda de água do sorgo forrageiro e do feijão-caupi cultivados no Estado de Pernambuco. Foram utilizados os valores mensais da normal climatológica brilho solar, temperatura do ar, umidade relativa do ar e velocidade do vento de dez municípios. Considerou-se um aumento de 1,8°C (Cenário B2) e 4,0°C (Cenário A1F1) na temperatura do ar e um decréscimo de 5,0% dos valores absolutos de umidade relativa do ar, além do aumento de 22% na resistência estomática e de 4% no índice de área foliar. Com base nessas informações foram gerados três cenários: situação atual e projeções futuras para B2 e A1F1. Os resultados revelaram uma redução média de 11% (B2) e 20% (A1F1), e de 10% (B2) e 17% (A1F1) na duração do ciclo, e de 4% (B2) e 8% (A1F1), e 2% (B2) e 5% (A1F1) na demanda de água acumulada para o sorgo forrageiro e feijão-caupi, respectivamente. Conclui-se que a magnitude das reduções da duração do ciclo e a demanda de água simulada para as culturas do sorgo forrageiro e do feijão-caupi variaram espaço-temporalmente no Estado de Pernambuco com os cenários de mudanças climáticas.ABSTRACT The increase in the occurrence of extreme weather events in recent decades is a strong evidence of climate change. In semiarid regions, where the pressure of desertification has intensified, are expected to decrease in the availability of water and higher occurrence of drought periods, and, consequently, effects on physiological response of plants. Thus, the objective of analyzing the impacts of climate change scenarios on the duration of phenological cycle and water demand of forage sorghum and cowpea, grown in the State of Pernambuco. Monthly values were used normal climatological solar brightness, air temperature, relative humidity and wind speed of ten municipalities. It was considered an increase of 1.8° C (B2 Scenario) and 4.0° C (A1F1 Scenario) on air temperature and a decrease of 5.0% of the absolute values of relative humidity, in addition to the 22% increase in stomatal resistance and 4% in leaf area index. Based on this information were generated three scenarios: current situation and future projections for B2, A1F1. The results revealed an average reduction of 11% (B2) and 20% (A1F1), and 10% (B2) and 17% (A1F1) for the duration of the cycle, and 4% (B2) and 8% (A1F1), and 2% (B2) and 5% (A1F1) in accumulated water demand for forage sorghum and cowpea, respectively. It is concluded that the magnitude of the reductions in the duration of the cycle and the simulated water demand for crops of forage sorghum and cowpea ranged space-temporarily in the State of Pernambuco with climate change scenarios.

The environmental factors that affect the morphological characteristics of different genera of cacti are little known. The aim of this study therefore was to analyse the contribution of environmental variables to growth in cladodes and plant of forage cactus clones of the genera Nopalea and Opuntia. The data used in this study were obtained from an experiment conducted in Serra Talhada, Pernambuco, Brazil, between 2012 and 2013, where the clones ?IPA Sertânia? (Nopalea), ?Miúda? (Nopalea) and ?Orelha de Elefante Mexicana? (Opuntia) were submitted to different irrigation depths (2.5, 5.0 and 7.5 mm) and fixed irrigation intervals (7, 14 and 28 days). Morphological characteristics of the cladodes and plants and weather variables were obtained over time. Pearson?s correlation, followed by multicollinearity, canonical and path analysis were applied. The minimum temperature, maximum and minimum relative humidity, wind speed and solar radiation were the variables that most affected growth in the cactus. The genus Opuntia showed less sensitivity to variations in air temperature compared to the genus Nopalea. The higher intensities of global solar radiation affected clones of the genus Nopalea more than the genus puntia. It can be concluded that there are different environmental requirements between forage cacti of the genera Nopalea and Opuntia. Made available in DSpace on 2019-05-04T00:48:34Z (GMT). No. of bitstreams: 1 Environmentalvariablesinfluencingtheexpression.pdf: 83923 bytes, checksum: 2989a83c24972d7bac51f9c7a7bb1b27 (MD5) Previous issue date: 2018