Ivan Carlos Maldaner

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.

Necessidade de irrigação para o feijoeiro na região central do Rio Grande do Sul

The lack of knowledge about the likelihood of occurence of bad weather is a problem for production planning of the bean. This study aimed to determine the values of water depth and number of irrigations required for common bean at different sowing times, considering the storage capacity of available water (CAD) of the main soils of central region of Rio Grande do Sul . The cycle simulation was performed using the thermal time in ten sowing times (ES) and in each year of the historical series of meteorological data for the period between 1968 and 2006. Irrigation was simulated for 13 soils of the region covered by meteorological station of Santa Maria, which were grouped in six groups. To simulate the irrigation, four handlings were used: 0.8, 0.7, 0.6 and 0.5 corresponding to the maximum depletion of 20, 30, 40 and 50% of CAD, respectively. The variation of soil water content was determined by soil water balance, considering the irrigation. The greater demand for irrigation occurred in last sowing times of the main crop season and lowest at the begining of the main and second crop season. For the 90% probability of occurrence of the water depth ranged between 32 and 143 mm and the number of irrigations between 3 and 20 during cycle.

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.

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.

Evapotranspiração do pimentão em estufa plástica estimada com dados meteorológicos externos, na primavera

The objective of this work was to develop, test and validate mathematical models for maximum evapotranspiration estimations of a sweet pepper crop using meteorological variables measured outside the greenhouse, in Santa Maria, RS. Two experiments were conducted during spring of 2005 and 2006, for data collection, respectively for development and testing of models. The maximum evapotranspiration was measured using three drainage and one weighting lysimeter. Plant height, number of leaves and leaf area were weekly determined. The daily values of meteorological variables were obtained at the main Meteorological Station of Santa Maria. It is possible to estimate the maximum evapotranspiration of sweet pepper crop grown inside greenhouses during the spring with mathematical models that use various external measurements. Better estimations of maximum evapotranspiration of sweet pepper crop grown inside plastic greenhouse during the spring were obtained using meteorological variables, mean vapor pressure deficit, solar radiation, net radiation and reference evapotranspiration, measured outside the greenhouse. It was concluded that it is possible to estimate, with acceptable accuracy at daily level, the maximum crop evapotranspiration of sweet pepper grown in greenhouse in spring, using complex mathematical models that use meteorological variables measured outside the greenhouse.

Produtividade da batata em função da irrigação e do controle químico da requeima

The objective of this study was to determine the effect of different levels of irrigation and chemical control on yield and occurrence of Late Blight in potato cv. Asterix, at Santa Maria - RS. Two experiments were conducted at the Crop Science Department, Federal University of Santa Maria. One experiment was carried out during spring-summer, 2005/2006 and the second, during fall 2006. The experimental design was a complete randomized, with four replications. The Blitecast model was used to indicate the timing of spraying, by accumulating severity values (VS). Sprinkler irrigation was used corresponding to 1.0, 0.75, 0.50 ETm and no irrigation. Results showed that in dry and high temperature periods, yield was affected by irrigation, mainly when crop water demand was supplied with 100% ETm. During wet periods, yield was affected by the efficient control of Late Blight. The Blitecast model with a severity value of 18 (Bli18) was the most efficient for controlling the disease. Irrigations applied at least every three days did not affect Late Blight incidence and development.

Balance of longwave radiation employing the rate of solar radiation for Santa Maria, Rio Grande do Sul, Brazil.

New coefficients were determined for the weighting term for cloudiness in the Brunt-Penman equation using the rate of solar radiation (R K ) in place of the rate of sunshine duration (). The coefficients in the Brutsaert method proposed for daytime in southern Brazil were also tested and adjusted, and the method was selected which gave the more accurate daily results in relation to the original Brunt-Penman equation, for Santa Maria in the state of Rio Grande do Sul, Brazil (RS). Meteorological data covering 2,472 days obtained from the automatic and conventional weather stations in Santa Maria were used. The coefficients were adjusted by linear and nonlinear regression methods depending on the model, using 2/3 of the data. The adjusted equations were tested with the remaining 1/3 of the data. The Brunt-Penman equation modified by the term for cloudiness weighted both for solar radiation incident on the surface with no cloudiness (R K,R ) and for solar radiation incident at the top of the atmosphere (R K,K ), were those that resulted in the best statistical indices relative to the original Brunt-Penman equation. In those equations the boundary conditions, 0.3 iR K,R i 1 or R K,K �i 0. 2 2, we r e imposed. Although having similar statistical indices, a sensitivity analysis showed that the Brutsaert equation and other weightings for cloudiness resulted in larger deviations when compared to the original Brunt-Penman equation, in addition to having greater complexity for practical application.

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.