Ana Beatriz Costa Czermainski

Generalização de um índice de intensidade de infecção em experimentos de avaliação de doenças em plantas

In plant disease experiments, individuals of each experimental unit are commonly classified according to categories of a discrete quantitative scale through visual assessment of disease severity. This paper shows the generalization of a measure that associates a quantitative response called infection intensity index, expressed as I=sen2w, to each distribution of frequencies obtained in the units. Its angular transformation w=arcsen I0,5 allows the application of the analysis of variance. Since the calculation of w does not involve the values or notes of the scale it can also be used with a qualitative ordinal scale.

Influência das condições climáticas sobre a eficácia de fungicidas empregados para o controle do míldio em Vitis vinifera

One of the factors to be managed for maximum vineyard productivity is the downy mildew, disease caused by Plasmopara viticola that affects grape production in many parts of the world. In Brazil, several fungicide applications for its control are necessary. Different active ingredients are available on the market. The influence of climatic factors (air temperature, rainfall and relative humidity) on fungicide efficacy in Vitis vinifera was analyzed using results of fungicide trials for downy mildew control as a base. The experiments were carried out at Embrapa Uva e Vinho with the cv. Tannat conducted on vertical trellis system during 1995 and 1996. The assessment of the environmental factors pointed out primary and secondary infection periods, being the rainfall and high relative humidity responsible for the high severity in the year 1996. The analysis of the incidence and of the disease rate on leaves and bunches, indicated that the most efficient treatments were cymoxanyl + mancozeb, metalaxyl + mancozeb and dithianon, in the two years. The active ingredients copper oxychloride, alone or combined with mancozeb, and copper sulphate were not efficient for downy mildew control on bunches under favorable environmental conditions to this disease.

Micropropagação de porta-enxertos híbridos de Vitis labrusca x Vitis rotundifolia com resistência à pérola-da-terra (Eurhizococcus brasiliensis Hempel, Hemiptera: Margarodidae)

The homogeneous production of rootstock resistant to perola-da-terra (Eurhizococcus brasiliensis Hempel, Hemiptera: Margarodidae) and well adapted to the growth conditions of the main grape growing region of Southern Brazil by the use of the micropropagation technique, may come to solve the demand of the grape productive sector and avoid losses caused by this pest. The objective of this work was to develop a protocol of micro propagation for the hybrids 1 and 2, which have the desired genetic qualities and vigor to be used as rootstock resistant to perola-da-terra. From axillaries buds cultivated in Galzy culture medium with 3µM of BAP, it was possible to induce multiple shooting with a reasonable number of shoots, which may be improved by successive subcultures in the same medium. The shoots were transferred to Galzy culture medium with 8µM.10-3 of NAA and all of them rooted, overcoming the rooting step that has been pointed out as the main barrier for micro propagation of the species Viits rotundifolia and its hybrids.

Modelo autologístico espaço-temporal com aplicação à análise de padrões espaciais da leprose-dos-citros

The goal of this study was to propose modeling strategies applied to the analysis of citrus leprosis incidence, through the use of a spatial temporal autologistic model. We evaluated the adequacy of autologistic model to consider data collected at different times; to detect spatial-temporal patterns through different neighboring structures; to consider the effect of covariates from previous times; and assessing the effect of the presence of the disease vector in the probability of new infections occurrence. The spatial temporal autologistic model adopted has extended the usual logistic model, in which the neighboring structures is described by means of covariates built from the status of plants nearby, at the same or at previous times. Data regarding the presence of the leprosis on plants were collected at field points referenced in space, over a period of approximately two years. Models detect the presence of spatial patterns on new infections for the studied neighboring structures, at the same or previous time. Additionally, probability estimates of a plant become infected can be obtained from the fitted models, given the occurrence of the disease and vector.

ESTÁDIOS DE DESENVOLVIMENTO DE EMBRIÕES NA OBTENÇÃO DE PLANTAS EM CRUZAMENTOS ENTRE GENITORES APIRENOS DE VIDEIRA

It was investigated the effect of the growth stage of rescued embryos on plant obtention from crosses between seedless grape parents. Two methods for in vitro culture were compared. Method 1 (M1): seed traces were cultured 60 days in ER culture medium. Method 2 (M2): procedure of M1 followed by additional 30 days in MS culture medium. The stage of embryo growth was established at the end of this period, when the embryos were rescued and transfered to WP culture medium. Four classes of embryo stages were indentified: globular, heart, torpedo and undefined. The globular stage, the most frequently found, produced the largest quantity of recovered plants, though it had the lowest capacity of originating plants. The torpedo stage was the most efficient in producing plants. M2 promoted the largest amount of germinated embryos and recovered plants. As the embryo growth stage affects the plant obtention, the rescue of embryos in an advanced growth stage promotes a higher capacity of producing plants. Therefore the use of techniques that favour the rescuing of embryos in an advanced growth stage can increase the obtention of plants.

Extended cold storage of winter pears by modified atmosphere packaging.

O objetivo deste trabalho foi avaliar a eficiencia da atmosfera modificada na manutencao dos atributos de qualidade e na extensao do armazenamento refrigerado de peras ‘Rocha’ e ‘Packham’s Triumph’. Os frutos foram acondicionados em filme de polietileno de baixa densidade linear (100 µm) com aditivo BIF 1.500 6% no interior de caixas plasticas vazadas e mantidos a 0 ± 1 °C e 90 ± 5% UR por ate 180 dias. A atmosfera modificada reduziu em 14,8% a perda de massa de peras ‘Rocha’ e em 11,5% a de peras ‘Packham’s’, apos 180 dias de refrigeracao, e mostrou-se util na preservacao da coloracao verde dos frutos, retardando em 60 e 90 dias a percepcao visual do amarelecimento da casca de peras ‘Rocha e Packham’s’, respectivamente. Houve amolecimento excessivo da polpa de peras ‘Packham’s’ controle apos 150 dias a 0 °C, seguidos por 5 dias a 20 °C, o que nao limitou o armazenamento das peras de ambas as cultivares sob atmosfera modificada. A atmosfera modificada proporcionada pela embalagem de polietileno de baixa densidade linear (100 µm) com aditivo BIF 1.500 6%, proporcionou a extensao de 30 dias no periodo de armazenamento refrigerado de peras ‘Rocha’ e de 60 dias para ‘Packham’s Triumph’.

Desempenho agronômico de videiras com e sem sintomas de viroses, e comparação molecular de isolados virais

The objective of this work was to evaluate the effect of viroses in symptomatic and asymptomatic grapevines on the agronomic variables related to the plant vigor and the enological quality of grapes, and to compare viral isolates obtained from these two conditions. Two experiments were performed with four cultivars. All plants were indexed by real time, reverse transcription‑polymerase chain reaction (RT‑PCR) for the probable occurrence of the following viruses: Grapevine virus A (GVA), Grapevine virus B (GVB), Grapevine virus D (GVD), Grapevine leafroll‑associated virus (GLRaV‑1 to ‑4, GLRaV‑4 strain 5), Grapevine rupestris stem pitting‑associated virus (GRSPaV), and Grapevine fleck virus (GFkV). The evaluated variables were: number of buds burst and not burst, number of branches with or without bunches, total number of buds, number of bunches, fresh bunch weight, total berry weight, rachis weight, number of berries per bunch, average berry weight, total soluble solids, total titratable acidity, pH, pruned branch weight, or rootstock and scion trunk diameters. The negative effects were more pronounced on the plants with virus symptoms; however, it was observed that plants without symptoms were also often infected. The molecular analysis of GRSPaV, GVA, and GLRaV‑2, isolates from symptomatic and asymptomatic plants, resulted in a high percentage of nucleotide identities between homologous isolates.

Spatial patterns of the Citrus leprosis virus and its associated mite vector in systems without intervention

R. B. Bassanezi* , A. B. C. Czermainski, F. F. Laranjeira, A. S. Moreira , P. J. Ribeiro J unior, E. T. Krainski and L. Amorim Research & Development Department, Fundecitrus, CP 391, 14801-970 Araraquara, SP; Embrapa Grape & Wine, CP 130, 95700-000 Bento Gonc alves, RS; Embrapa Cassava & Fruits, 44380-000 Cruz das Almas, BA; Department of Statistics, Federal University of Parana, CP 19081, 81531-990 Curitiba, PR; and Plant Pathology and Nematology Department, University of Sao Paulo, CP 9, 13418-900 Piracicaba, SP, Brazil

ALTERNATIVE FOR REDUCING PHYSIOLOGICAL DISORDERS IN ‘BARTLETT’ PEARS

‘Bartlett’ pears from different harvest dates were assessed regarding to cold storage potential and reduction of physiological disorder incidence. Three harvests, the first (HD1), second (HD2), and third (HD3), were carried out at weekly intervals. The pears were assessed after the harvest, with no exposition to the temperature conditioning, after 20, 40, 60, 80, 100 and 120 days at 0 ± 1 °C and 90 ± 5% RH and after three and six days at room temperature (20 ± 1 °C). Fruit from the early harvest (HD1) showed the smallest incidence of physiological disorder during both cold and room temperature storage. The disorder symptoms became apparent in HD1 fruit after 20 days at cold storage followed by three days at 20 °C, whereas HD2 and HD3 fruit showed the symptoms before being kept in a cold room. ‘Bartlett’ pears harvested at 70.75 N flesh firmness can be stored at 0 ± 1 °C for up to 40 days and preferably commercialized within three days, when they reach the firmness for eating. The extension of cold storage as well as the trade period can result in higher physiological disorder incidence and loss of sensorial quality.

Effect of water restrictors on the germination, radicle length and detection levels of Colletotrichum gossypii var. cephalosporioides in cotton seeds

The fungus Colletotrichum gossypii var. cephalosporioides, causal agent of ramulosis of cotton, is transmitted by seeds and is one the most important source of inoculum and the introduction of disease in health areas. To detect the pathogen in the cotton seeds it is important the use of a safe and quick method. The common method is the blotter test which is based on the evaluation of pathogen growing on the seeds and the morphological identification of pathogens. The method presents the disadvantage of seedlings growing during the seeds incubation period, which can be favorable to development of contaminants fungi and to difficult the identification of main pathogen. To avoid this problem the water restriction technique had been used. The objective of this research to study the effect of water restriction in the blotter method with manitol, NaCl and KCl, in two osmotic potential, -0,6 and -0,8, compared to pattern of distilled water and 2,4 D added to the substrate and the freezing technique, in relation to seed germination, radicle elongation and incidence of the pathogen on the seeds. The manitol and NaCl, with osmotic potential of -0,8 MPa were more efficient to inhibit the germination and promoted higher incidence of the pathogen. The KCl was efficient to inhibit the germination in the two osmotic potentials of -0,6 and -0,8, but the incidence of the pathogen was reduced. The manitol and NaCl in the osmotic potential of -0,8 MPa were efficient to reduce the germination and radicle elongation but not reduced the incidence of the pathogen on the seeds. This technique can be used in routine health test to detect C. gossypii var. cephalosporioides in seed cotton.