Dionéia Daiane Pitol Lucas

Modelos de determinação não-destrutiva da área foliar em girassol

The objective of this study was to obtain and to numerical models to estimate the leaf area in function leaves linear dimension in sunflower. Two experiments were conducted at the experimental area of the Plant Science Department of the Federal University of Santa Maria, Santa Maria, RS, Brazil. Plants of sunflower were collected starting 27 days after emergency (DAE). The disks method was used to determine the leaf area (LA). Leaves were dried in oven at 65°C until constant weight. Linear, quadratic, cubic and power models between leaf area and length or width, and the product (length * width), were fitted. Models that apresented coefficient of determination lower than 0.90 were not selected. The statistic used to evaluate the performance of the models was the root mean square error (RQME). Models that had the best fit were power, quadratic and cubic using blade width as the independent variable. Leaf area in sunflower can be estimated with the power model, which was the most accurate, with width of the leaf.

Filocrono, área foliar e produtividade de frutos de berinjela conduzidas com uma e duas hastes por planta em estufa plástica

The objective of this study was to estimate the phyllochron, to associate the leaf area to the leaf number and to determine fruit yield of eggplants grown with one and two stems inside a plastic greenhouse. An experiment was carried at the experimental area of the Plant Science Department of the Federal University of Santa Maria, Santa Maria, RS, Brazil. Three eggplant genotypes were used: Napoli, Comprida roxa, and Cica. Five-leaf seedlings were transplanted on 10/29/2007. The experimental design was a complete randomized blocks with four replications composed by two rows with eight plants. The number of leaves on the main stem and secondary branches was counted in four plants of each replication. Leaf width was measured on two plants per replication. The phyllochron was estimated as the inverse of the slope of the linear regression between the leaf number and the accumulated thermal time after transplanting. Eggplant fruit yield was greater in plants grown with two stems than and Cica had the higher fruit yield among genotypes. The time for leaves emergence in eggplant was reduced in plants with two stems than in plants with only the main stem. Leaf area of eggplant can be estimated as function of the accumulated number of leaves. Eggplant fruit yield was greater in plants conducted with two stems than with only the main stem, and Cica presented the greatest yield among genotypes.

Sistema de previsão de ocorrência de requeima em clones de batata suscetíveis e resistentes

Forecasting systems and late blight resistant cultivars are important tools to reduce the amount of fungicides and the production cost of a potato farm. The objective of this study was to evaluate the Blitecast forecasting system for late blight occurrence and susceptible and resistant potato clones for managing late blight in Santa Maria, RS, Brazil. Experiments were conducted at the Federal University of Santa Maria during the Spring 2006 and Autumn 2007. Meteorological data were measured continuously above the crop canopy. Ten treatments were used in a completely randomized design, with four replications. Treatments were different values of accumulated severity, calculated by the Blitecast forecasting system and by the potato clones SMIJ461-1 and SMINIA793101-3, characterized as resistant, and the clone Macaca as susceptible to late blight. The Blitecast forecasting system was not effective for predicting the time of fungicide spraying for the control of late blight and, therefore, to be used in susceptible clones it has to be adjusted. For resistant clones, the fungicide spraying based on the Blitecast system has no effect on late blight occurrence and potato productivity.

Saldo de radiação diurno em dosséis de batata como função da radiação solar global

The objective of this work was to determine the relationship between net radiation (Rn) and incident solar radiation (Rg) in potato canopy at six different cultivation periods and stages of development in order to generate linear models that describe this relationship. The experiments were conducted in the experimental area of University of Santa Maria, RS, in the years of 2004 to 2007. Rn was measured by net radiometers in six experiments and Rg by automatic weather station, situated 30 to 80 m from the experiments. For purposes of calculation, were performed daily sums of Rn and Rg. Through these, it was calculated the Rn/Rg ratio for each day. There was obtained a good relationship between changes in Rn and Rg. This relationship was confirmed in the regression analysis, obtaining models with high correlation coefficient, indicating precisely to estimate net radiation in potato canopies as a function of incident solar radiation (Rg), irrespective of season. The function general linear obtained with data from different years, growing seasons and genotypes was not sensitive to leaf area index, resulting in: Rg Rn = 0.6410 (R2 = 0.976), that in the test showed RQME = 0.75 MJ m-2 dia-1. The diurnal energy flux density of net radiation can be estimated through using the flux density of global solar radiation measured in automatic stations with sufficient accuracy for modeling.

Severidade de ocorrência das manchas de alternária e septoriose em girassol semeado em diferentes épocas no Rio Grande do Sul

The sunflower cultivation has received great attention because of their agronomic characteristics and the possibility of inclusion in crop rotation systems. However, the different climatic conditions prevailing in the growing season determine the occurrence or not of the disease, so that this knowledge is critical for choosing the best growing season. This study aimed to determine the severity of Alternaria and Septoria leaf spots on sunflower (Helianthus annuus) at different sowing dates. Experiments were carried out during four seasons, from 2007 to 2011, in Santa Maria, state of Rio Grande do Sul, Brazil. The experiments had a completely randomized design with two-factor (sowing dates vs. sunflower hybrids). The measurements of plant growth and severity of leaf spots caused by Alternaria and Septoria were taken once and twice a week, respectively. The final severity (SVFO) and the variables area under the disease progress curve (AACPD) and days of healthy leaf area (DAFS) were determined and used for comparing hybrids and sowing dates. In the crop seasons of 2007/2008, 2008/2009 and 2010/2011, the severity of disease was lower for early sowing dates from August to September, while the later ones tended to increase the disease severities. In 2009/2010 growing season, period under El Nino influence and with rainfall above normal, all sowing dates resulted in high disease severity, especially negative for the first sowing dates because of the highest rainfall in years under the phenomenon influence. Therefore, the late sowing or sowing during El Nino years are favorable to high Alternaria and septoria leaf spots severity in sunflower crop and then the sowing should be avoided under those conditions.

Modelagem da emissão de folhas em arroz cultivado e em arroz-vermelho

The objective of this work was to simulate leaf appearance in cultivated rice genotypes and in red rice biotypes, by adapting the Wang and Engel model modified by Streck et al. Two experiments were conducted in Santa Maria, Rio Grande do Sul State, Brazil, during 2004/2005 and 2005/2006 growing seasons. Cultivars IRGA 417 and EEA 406, one hybrid, and two red rice biotypes were used. The leaf appearance model was adjusted, using Haun Stage (HS) data from five sowing dates of 2004/2005 growing season, and the model evaluation was performed using HS data from three sowing dates of 2005/2006 growing season. A numerical experiment was also carried out using temperature data occurred during 2003/2004 and 2006/2007 growing seasons, and simulated HS of the cultivated rice genotypes was compared with the red rice biotypes. The model had a good performance, with a root mean square error usually less than one leaf. Main stem leaf emergence was greater in modern genotypes IRGA 417 and hybrid than in the old genotype EEA 406. Leaf emergence is different among distinct red rice biotypes.

Excedente hídrico em diferentes solos e épocas de semeadura do girassol no Rio Grande do Sul

The objective of this work was to identify sowing dates with the lowest average occurrence of days with water excess for sunflower crop, and to determine the persistence of consecutive days with water excess considering the available water storage capacity of different soils of the central region of the state of Rio Grande do Sul, Brazil. Crop development and root system deepening were simulated based on thermal summation for 14 sowing dates, from August until mid‑February, with data from 1968 to 2011. From the available water storage capacity of the different soil classes of the region, the sequential daily water balance was calculated to determine the days with water excess. The occurrence of days with water excess was evaluated in different crop development sub‑periods, and exploratory analysis with box‑plot graphs was performed to determine the persistence of consecutive days with water excess during the crop cycle. Water excess limits sunflower cultivation in some areas and periods in the central region of the state of Rio Grande do Sul. The persistence of consecutive days with water excess and the duration of the crop development cycle are influenced by the sowing date.

Sistemas de previsão de requeima em cultivos de batata em Santa Maria, RS

The forecast systems are an alternative to the efficient control of late blight potatoes and consequent reduction in the amount of fungicide and thereby reduce production costs and environmental pollution. The objective of this study was to evaluate forecast systems, Blitecast and Prophy, for late blight occurrence in Macaca potato cultivar in Santa Maria, Rio Grande do Sul State, Brazil. The experiments were carried out during Spring 2006 and Autumn 2007 with the Macaca cultivar characterized as susceptible to late blight. Meteorological data were collected at the center of the experimental area with an automatic station and with psicrometers installed at different heights. The treatments were arranged in a completely randomized design, with four replications. Treatments were differentiated by using accumulated values of severity, which were calculated by the Blitecast and Prophy forecasting systems. The values of severity accumulated had the purpose of indicating the time of fungicide application for late blight control. The use of the forecast system of late blight, Prophy, with accumulation of 15, 20 or 25 values of severity, and system Blitecast with 24 accumulated severity for a potato susceptible genotype, Macaca, reduces the number of applications of fungicides without affecting productivity.

Evapotranspiração máxima e coeficiente de cultura da berinjela cultivada em estufa plástica

The eggplant cultivation in plastic greenhouse has increased in Southern Brazil. However, little is known about crop evapotranspiration in plastic greenhouse condition for proper irrigation. This study aimed to determine the maximum evapotranspiration and crop coefficient of eggplant cultivated in plastic greenhouse. Three experiments were carried out under plastic greenhouse, two in spring of 2006 and 2007 and another in fall of 2007 under the subtropical climate conditions of Santa Maria, RS. Plants were grown on ridges, covered with plastic mulching and drip irrigated. The maximum crop evapotranspiration was measured in six replications of drainage evapotranspirometer containing 20 L of substrate and one plant. The reference evapotranspiration was calculated by Penman-Monteith method. It was found that the maximum crop evapotranspiration in spring is greater than in fall, while the crop coefficient was greater in fall. It was concluded that crop coefficient of eggplant cultivated in plastic greenhouse can be estimated with good accuracy as a function of days after transplantating or leaf area index.

Escala diagramática de quantificação de dano causado por granizo em folhas de girassol

The objective of this study was to develop a diagrammatic scale for the visual assessment and the quantification of hail damage in sunflower leaves. The study was carried out in an experimental area in Santa Maria (RS) during the agricultural year of 2008/2009, the damage being caused by a hail-storm event which occurred on 8 January, 2009, with the sunflower plants in full bloom (R5.1) and a leaf-area index of 2.2 m 2 m -2 . A total of 243 damaged leaves were collected, which before collection had their outlines redrawn with the aid of complete leaves of similar shape. After determining the percentage of the damaged area, images were selected to make up the diagrammatic logarithmic scale. A test of the scale was undertaken by 10 different observers on 24 randomly selected leaves from the 243 collected. The accuracy and precision of each appraiser were determined by simple linear regression of actual damage and that estimated with the aid of the diagrammatic scale, in addition we used the Root Mean Square Error (RMSE), the absolute error and the coefficient of determination (R 2 ) of the linear regression. It was found that the scale