Francislene Angelotti

Diagrammatic scale for assessment of grapevine rust

A diagrammatic scale with six levels of disease severity (1, 5, 12, 25, 50 and 75%) was developed to assess grapevine (Vitis spp.) rust severity, caused by the fungus Phakopsora euvitis. Two versions of the scale, in black-and-white and in color, were validated by seven raters without previous experience with grapevine rust, who estimated the severity of 30 grapevine leaves showing rust symptoms, with and without the use of the scales. Precision and accuracy were determined by linear regression, relating the assessments using the scales to actual severity. Actual severity was assessed with the software ASSESS®. Using the diagrammatic scales, some raters were able to improve precision and accuracy. The color scale provided slightly more precise and accurate estimates than the black-and-white scale.

Research approaches, adaptation strategies, and knowledge gaps concerning the impacts of climate change on plant diseases

This review discusses the present trends in studies on the impacts of climate change on plant diseases. Firstly, the approaches used for studying the potential effects of altered temperature, water availability, CO2 and O3 air concentrations, and UV-B radiation on components of the disease cycle are explained and discussed. Next, the impact of changes in climate patterns on the geographic and temporal distribution of diseases by integrating biological and epidemiological models into geographic and climate databases are assessed. Finally, adaptation strategies are discussed and areas where there is a recognized lack of knowledge are highlighted. The literature shows that different pathosystems respond in different ways to climate change. Thus, case-by-case studies on the responses of crop species or varieties and their diseases to climate change are necessary. In addition to that, wide-scale projections of disease risk are necessary in order to identify research priorities, whereas industry must be strategically directed and public policies developed to establish adaptation measures and to prevent potential food security crisis. Only by conducting long-term and multidisciplinary studies can we reduce the uncertainty regarding the effects of climate change on plant diseases.

Resistência de genótipos de videira à ferrugem

O objetivo deste trabalho foi avaliar a resistencia a ferrugem causada pelo fungo Phakopsora euvitis, em genotipos de videira, e a efi ciencia da infeccao de acordo com a idade das folhas e concentracao de inoculo. A avaliacao foi feita em 15 genotipos, com base nos seguintes componentes de resistencia: numero de pustulas (uredios) por cm2; tamanho das pustulas; numero de esporos produzidos por pustula; e periodo latente. Os componentes de resistencia, com excecao do periodo latente, apresentaram grande variacao quantitativa. A analise multivariada desses componentes diferenciou cinco grupos de genotipos. Os genotipos mais resistentes foram as cultivares porta-enxertos IAC313, IAC572 e IAC766, em que a efi ciencia da infeccao foi baixa, com pustulas menores e menor producao de urediniosporos, alem de reacao de hipersensibilidade no tecido em torno das pustulas. O grau de infeccao aumenta com o aumento na concentracao do inoculo. A ferrugem coloniza, indiscriminadamente, folhas jovens e folhas maduras de videira.

Efeito da temperatura e da luz na germinação de urediniósporos de Phakopsora euvitis.

ABSTRACT The objectives of this research were to analyze the effect oftemperature and light on in vitro germination of Phakopsora euvitis urediniospores, as well as the viability of urediniospores stored underdifferent temperatures. For determined the incubation period wasevaluate the germination of urediniospores in water-agar 2%, for 2,4, 6, 8, 10, 12 e 24 h. In order to evaluate the effect of temperatureand light in germination, uredinio spores in a suspension onto petri dishes were kept at 15, 20, 25 and 30 °C for 24 h, in the dark andunder continuous light. For the viability study, urediniospores were Angelotti, F.; Tessmann, D.J.; Scapin, C.R.; Vida, J.B. Effect of temperature and light on germination of uredinispores of Phakopsora euvitis . Summa Phytopathologica, v.37, n.1, p.59-61, 2011. armazenados em tubos Eppendorf foram mantidos nas temperaturas de –20±2, 5±2, 23±2 e 33±2 o C, no escuro. Verificou-se o aumento continuona germinacao dos esporos entre as avaliacoes com 6 a 24 horas deincubacao. As temperaturas cardinais (minima, otima e maxima) para agerminacao de urediniosporos

Productive and morphogenetic responses of buffel grass at different air temperatures and CO2 concentrations

The objective of the present trial was to evaluate the productive and morphogenetic characteristics of buffel grass subjected to different air temperatures and CO2 concentrations. Three cultivars of buffel grass (Biloela, Aridus and West Australian) were compared. Cultivars were grown in growth chambers at three temperatures (day/night): 26/20, 29/23, and 32/26 °C, combined with two concentrations of CO2: 370 and 550 µmol mol-1. The experimental design was completely randomized, in a 3 × 3 × 2 factorial arrangement with three replications. There were interactions between buffel grass cultivars and air temperatures on leaf elongation rate (LER), leaf appearance rate (LAR), leaf lifespan (LL) and senescence rate (SR), whereas cultivars vs. carbon dioxide concentration affected forage mass (FM), root mass (RM), shoot/root ratio, LL and SR. Leaf elongation rate and SR were higher as the air temperature was raised. Increasing air temperature also promoted an increase in LAR, except for West Australian. High CO2 concentration provided greater SR of plants, except for Biloela. Cultivar West Australian had higher FM in relation to Biloela and Aridus when the CO2 concentration was increased to 550 µmol mol-1. West Australian was the only cultivar that responded with more forage mass when it was exposed to higher carbon dioxide concentrations, whereas Aridus had depression in forage mass. The increase in air temperatures affects morphogenetic responses of buffel grass, accelerating its vegetative development without increasing forage mass. Elevated carbon dioxide concentration changes productive responses of buffel grass.

Seasonal progression of leaf rust in ‘Niagara Rosada’ grapevine in a biannual crop system in Brazil

Grapevine leaf rust, which is caused by the fungus Phakopsora euvitis, is an important late-season disease of ‘Niagara Rosada’ (Vitis labrusca) grapevine in Brazil. The early defoliation of plants caused by the disease impairs fruit ripening and reduces marketable yield. In a study carried out in northern Paraná State, the temporal progression of grapevine leaf rust was quantified in a production system of ‘Niagara Rosada’ grapevine with two growing seasons per year: mid-summer-autumn and late winter-spring. The influence of weather-related variables on rust progression was examined through correlation analyses. It was observed that the rust was more severe in summer-autumn than in winter-spring. Significant positive linear correlations (P ≤ 0.05) were found between rust severity and rainfall (r ≥ 0.90) and average daily hours of leaf wetness (r ≥ 0.82). In addition, negative correlation was found between rust severity and temperature (r ≥ −0.84) in the mid-summer/autumn season. Mild temperatures in autumn were considered decisive for rust progression. In Brazilian tropical viticulture, management strategies for grapevine leaf rust must consider the risk of rust damage in autumn caused by temperature.

Infection by Xanthomonas campestris pv.viticola under temperature increase and carbon dioxide concentrations.

The experiments were carried out under controlled conditions to evaluate the impact of increased temperature and concentration of carbon dioxide on infection of Xanthomonas campestris pv viticola, the causal agent of bacterial canker in Vine seedlings. It proceeded the evaluation of the following epidemiological components: incubation period (PI), severity (SEV) and using that data were calculated the area under the disease progress curve (AUDPC). It used grape seedlings (Italia, Crimson Seedless, Sugraone and Selection 8) inoculated with bacterial suspension (108 CFU mL-1). The experimental design was completely randomized, factorial arrangement 4x4 (cultivar x temperature) and 4x2 (cultivar x carbon dioxide concentration) which was carried out twice. The data were subjected to variance analysis. Increasing temperature reduced bacterium’s incubation period with significant differences between genotypes. For Selection 8 and Crimson temperature increase caused enhancement on severity and AUDPC. For Selecao 8 the incubation period (PI) was extended from 7.93 to 30.18 days when the concentration changed from 390 to 770 µmol/mol. The increased CO2 concentration reduced AACPSD and SEV for Sugraone and Selection 8. The results show that the temperature and carbon dioxide (CO2) concentration of the air may have different effects on bacterial canker of grapevine.

Onion Seedlings Emergence and Initial Growth Under Increased Temperature and CO2

Climate change, especially atmosphere temperature and concentration of greenhouse gases increase, will affect plant growth and development . The aim of this study was to evaluate the effect of increased temperature and CO2 concentration in emergence of seedlings of onion cultivars Alfa San Francisco, Franciscan IPA 10, Valley IPA 11 Gold and Serena. The experiment was conducted in growth chambers with humidity, light, temperature and CO2 control during 12 days. The experimental design was completely randomized in a 4x4x2 factorial scheme, with four onion cultivars , four temperatures (25 °C; 28 °C, 31 °C and 34 °C and two concentrations of CO2 (380 to 770 ppm), with four replications and 36 seeds per treatment. Seeds of onion cultivars Alfa São Francisco, Franciscana IPA 10, Vale Ouro IPA 11 and Serena were sown in plastic trays with 36 cells containing commercial substrate and placed in different CO2 concentrations and temperature. Emergence percentage, average time of emergence, emergence speed, emergence speed index, shoot length and root length was evaluated. The data were submitted to variance analysis and the averages compared by Scott Knott test at 5% probability. The CO2 concentrations and different temperatures produced different effects among cultivars for most of the variables. The increase of CO2 and temperature influence the emergence onion seedlings process. Key-words: climate change, impacts, agriculture Revista Brasileira de Geografia Física v.08, número especial IV SMUD (2015) 471-483. Costa; D. C. C. da.; Pinheiro; G. de S.; Oliveira; G. M. de.; Santos; A. T. N. dos.; Santana; C. V. da S.; Angelotti; F..; Dantas, B. F.