Response of Wheat Fungal Diseases to Elevated Atmospheric CO2 Level

Infection with fungal pathogens on wheat varieties with different levels of resistance was tested at ambient (NC, 390 ppm) and elevated (EC, 750 ppm) atmospheric CO2 levels in the phytotron. EC was found to affect many aspects of the plant-pathogen interaction. Infection with most fungal diseases was usually found to be promoted by elevated CO2 level in susceptible varieties. Powdery mildew, leaf rust and stem rust produced more severe symptoms on plants of susceptible varieties, while resistant varieties were not infected even at EC. The penetration of Fusarium head blight (FHB) into the spike was delayed by EC in Mv Mambo, while it was unaffected in Mv Regiment and stimulated in Mv Emma. EC increased the propagation of FHB in Mv Mambo and Mv Emma. Enhanced resistance to the spread of Fusarium within the plant was only found in Mv Regiment, which has good resistance to penetration but poor resistance to the spread of FHB at NC. FHB infection was more severe at EC in two varieties, while the plants of Mv Regiment, which has the best field resistance at NC, did not exhibit a higher infection level at EC. The above results suggest that breeding for new resistant varieties will remain a useful means of preventing more severe infection in a future with higher atmospheric CO2 levels

Post-processed data and graphical tools for a CONUS-wide eddy flux evapotranspiration dataset

Large sample datasets of in situ evapotranspiration (ET) measurements with well documented data provenance and quality assurance are critical for water management and many fields of earth science research. We present a post-processed ET oriented dataset at daily and monthly timesteps, from 161 stations, including 148 eddy covariance flux towers, that were chosen based on their data quality from nearly 350 stations across the contiguous United States. In addition to ET, the data includes energy and heat fluxes, meteorological measurements, and reference ET downloaded from gridMET for each flux station. Data processing techniques were conducted in a reproducible manner using open-source software. Most data initially came from the public AmeriFlux network, however, several different networks (e.g., the USDA-Agricultural Research Service) and university partners provided data that was not yet public. Initial half-hourly energy balance data were gap-filled and aggregated to daily frequency, and turbulent fluxes were corrected for energy balance closure error using the FLUXNET2015/ONEFlux energy balance ratio approach. Metadata, diagnostics of energy balance, and interactive graphs of time series data are included for each station. Although the dataset was developed primarily to benchmark satellite-based remote sensing ET models of the OpenET initiative, there are many other potential uses, such as validation for a range of regional hydrologic and atmospheric models

Efeito da poda do tipo decote no controle da xylella fastidiosa em cultivares de cafeeiro "Decote" type pruning effect upon xylella fastidiosa control in coffee cultivars

A bactéria Xylella fastidiosa causa prejuízos à cafeicultura e o emprego de produtos químicos, até o presente, não tem possibilitado o controle econômico dessa bactéria. O manejo adequado do cafezal, desde o plantio, com o uso de mudas isentas da bactéria e o controle das cigarrinhas vetoras, são medidas que atenuam a incidência da doença. A utilização de podas, que tem sido recomendada como medida de controle em citros e videiras, não tem ainda eficiência comprovada para o cafeeiro. Neste trabalho, objetivou-se estudar a eficácia do emprego da poda do tipo decote em cafeeiros arábica como controle de X. fastidiosa. Para tanto, após o emprego desse tipo de poda em cafeeiros infectados pela bactéria, quantificou-se a proporção de elementos de vaso do xilema obstruídos pela bactéria, e avaliou-se a severidade dos sintomas externos de infecção provocados pela X. fastidiosa. Oito meses após a aplicação da poda, no mês de junho de 2003 (período seco), observou-se que as plantas estavam com 4% dos elementos de vaso do pecíolo, 2% na nervura principal e 1% no caule obstruído pela X. fastidiosa. No período chuvoso, 14 meses após a poda, a proporção de obstrução dos elementos de vaso diminuiu para 2% no pecíolo, 1% no caule e na nervura principal. A prática da poda diminuiu ligeiramente a proporção de elementos de vaso obstruídos pela bactéria apenas no período seco, uma vez que foi observado antes da poda um máximo de 6% de obstrução no pecíolo. Os novos ramos que brotavam no cafeeiro, na estação chuvosa, pareciam compensar a obstrução dos ramos mais velhos, diminuindo a proporção de obstrução dos elementos de vaso na planta. Em 2003, não houve diferenças na severidade do sintoma externo entre os tratamentos nos dois períodos, seca e chuvoso. Entretanto, no período seco de 2004, as cultivares Catuaí Vermelho IAC 81 e Mundo Novo IAC 515-20, enxertadas sobre o porta-enxerto 'Apoatã IAC 2258' de C. canephora, foram os tratamentos com maior severidade e, novamente no período chuvoso, as diferenças não foram observadas. Concluiu-se, portanto, que a prática da poda do tipo decote não resultou nesse experimento em um controle eficiente da X. fastidiosa em cafeeiros de C. arabica de pé-franco ou enxertados e infectados por esta moléstia.<br>Xylella fastidiosa plant colonization causes damages to the coffee production and nowadays there is no available economic chemical control to this bacterium. Adequate cultivation management as the use of bacteria-free scions and control of the insect vector (cicadas), are practices that may attenuate the disease incidence. Pruning, that has been recommended for citrus and vines for disease control, still does not have its efficiency proved for coffee plants. This research work aimed to quantify the proportion of xylem vessel elements obstructed by the bacteria, as well as to evaluate the disease external symptoms severity after the "decote" type pruning. In June 2003 (dry season), eight months after pruning, it was observed that 4% of the petiole vessel elements were obstructed by X. fastidiosa, 2% of the central vein and 1% of the stem. In the rainy season, 14 months after pruning, the obstruction proportion of vessel elements decreased to 2% in the petiole and to 1% in central vein and stem respectively. Therefore, the pruning practice decreased slightly the xylem vessel obstruction caused by the bacteria in the dry period, once prior to pruning a 6% obstruction in the petiole was observed. The new branches sprouted during the rainy season seemed to compensate obstruction in older branches, thus decreasing vase obstruction proportion. In 2003 there were no differences in the disease symptom severity among treatments in the two periods (dry and rainy season), however, in the dry period of 2004, 'Catuaí Vermelho IAC 81' and 'Mundo Novo IAC 515-20' cultivars, grafted on C. canephora 'Apoatã IAC 2258', presented higher severity and, again in the rainy period, differences were not observed. It was concluded that the "decote" type pruning practice did not result in a X. fastidiosa efficient control