G. Trentin

Copper uptake, accumulation and physiological changes in adult grapevines in response to excess copper in soil

AimsThis study investigated Cu uptake and accumulation as well as physiological and biochemical changes in grapevines grown in soils containing excess Cu.MethodsThe grapevines were collected during two productive cycles from three vineyards with increasing concentrations of Cu in the soil and at various growth stages, before and after the application of Cu-based fungicides. The Cu concentrations in the grapevine organs and the macronutrients and biochemical parameters in the leaf blades were analyzed.ResultsAt close to the flowering stage of the grapevines, the concentration and content of Cu in the leaves were increased. However, the Cu concentrations in the roots, stem, shoots and bunches did not correlate with the metal concentrations in the soil. The application of Cu-based fungicides to the leaves increased the Cu concentrations in the shoots, leaves and rachis; however, the effect of the fungicides on the Cu concentration in the berries was not significant. The biochemical analyses of the leaf blades demonstrated symptoms of oxidative stress that correlated with the Cu concentrations in soil.ConclusionsThe increased availability of Cu in soil had a slight effect on the levels and accumulation of Cu in mature grapevines during the productive season and did not alter the nutritional status of the plant. However, increased Cu concentrations were observed in the leaves. The evidence of oxidative stress in the leaves correlated with the increased levels of Cu in soil.

Liberação do N em solos de diferentes texturas com ou sem adubos orgânicos

The N release in the soil with organic fertilization is affected by various factors, such as the amount and the caractheristics of the added manure, climatic conditions and soil type. This study aimed to evaluate the effect of soil texture and the N release from two sources of organic fertilizer. Sandy loam soil (238mg clay kg-1), silt clay (470mg kg-1) and very-clay (605mg kg-1) were incubated, to which the poultry litter (47% N-NH4+) and the pig liquid slurry (14% N-NH4+) were added or not. The contents of N-NH4+ and N-NO3- was determined at 0, 7, 14, 28, 56 and 112 days after incubation and calculated the net mineralization and the percentage of available N and net mineral nitrogen in relation to the total and added organic N, respectively. The higher clay caused more gradually nitrification, regardless of the type of organic fertilizer added, which may helps to reduce the polluting potential of N. The net N mineralization was also higher in sandy loam soil. This confirms the recommendation to spread the supply of nitrogen to crops, particularly in sandy soils and slurry rich in N-ammonia. The results indicated that the official indices of efficiency of N release (IELN), of 80% for the pig liquid slurry and 50% for the poultry litter, may be overestimated. Therefore, it seems important to consider the N mineral of the soil in the calculation of the efficiency of the release to reduce the depletion of soil organic matter in a medium or long term. Finally, the results point to the need for further studies so that the soil texture classes are considered as a variable to the recommended nitrogen through organic fertilizers.

Biomass decomposition and nutrient release from black oat and hairy vetch residues deposited in a vineyard

A significant quantity of nutrients in vineyards may return to the soil each year through decomposition of residues from cover plants. This study aimed to evaluate biomass decomposition and nutrient release from residues of black oats and hairy vetch deposited in the vines rows, with and without plastic shelter, and in the between-row areas throughout the vegetative and productive cycle of the plants. The study was conducted in a commercial vineyard in Bento Goncalves, RS, Brazil, from October 2008 to February 2009. Black oat (Avena strigosa) and hairy vetch (Vicia villosa) residues were collected, subjected to chemical (C, N, P, K, Ca, and Mg) and biochemical (cellulose - Cel, hemicellulose - Hem, and lignin - Lig content) analyses, and placed in litter bags, which were deposited in vines rows without plastic shelter (VPRWS), in vines rows with plastic shelter (VPRS), and in the between-row areas (BR). We collected the residues at 0, 33, 58, 76, and 110 days after deposition of the litter bags, prepared the material, and subjected it to analysis of total N, P, K, Ca, and Mg content. The VPRS contained the largest quantities and percentages of dry matter and residual nutrients (except for Ca) in black oat residues from October to February, which coincides with the period from flowering up to grape harvest. This practice led to greater protection of the soil surface, avoiding surface runoff of the solution derived from between the rows, but it retarded nutrient cycling. The rate of biomass decomposition and nutrient release from hairy vetch residues from October to February was not affected by the position of deposition of the residues in the vineyard, which may especially be attributed to the lower values of the C/N and Lig/N ratios. Regardless of the type of residue, black oat or hairy vetch, the greatest decomposition and nutrient release mainly occurred up to 33 days after deposition of the residues on the soil surface, which coincided with the flowering of the grapevines, which is one of the phenological stages of greatest demand for nutrients.

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.

Crop response to organic fertilization with supplementary mineral nitrogen

Animal manure is applied to the soil as a nutrient source, especially of nitrogen, to plants. However, manure application rates can be reduced with the use of N fertilizer in topdressing. The aim of this study was to evaluate crop responses to different application rates of animal manure sources, used alone and supplemented with mineral N topdressing, in a no-tillage system. The study was carried out from 2005 to 2008 on a Hapludalf soil. The treatments consisted of rates of 10, 20 and 30 m3 ha-1 of pig slurry (PS), and of 1 and 2 t ha-1 of turkey manure (TM), applied alone and supplemented with topdressed N fertilizer (TNF), as well as two controls, mineral fertilization (NPK) and one control without fertilizer application. Grain yield in common bean and maize, and dry matter yield and nutrient accumulation in common bean, maize and black oat crops were evaluated. Nitrogen application in topdressing in maize and common bean, especially when PS was used at rates of 20 and 30 m3 ha-1, and TM, at 2 t ha-1, proved effective in increasing the crop grain yields, showing the viability of the combined use of organic and industrialized mineral sources. Nitrogen accumulation in maize and common bean tissues was the indicator most strongly related to grain yield, in contrast with the apparent nutrient recovery, which was not related to the N, P and K quantities applied in the organic sources. No clear residual effect of N topdressing of maize and common bean was observed on the dry matter yield of black oat grown in succession to the main crops with PS and TM applications.

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.

Copper Accumulation and Availability in Sandy, Acid, Vineyard Soils

ABSTRACT The use of copper (Cu)-based fungicides to control diseases in vineyards can cause excessive Cu accumulation in soils. Greater Cu availability is expected in acid sandy soils with low organic matter (OM), where the risk of toxicity to plants and environment contamination is high. This study aimed to study the evolution of Cu in acid, sandy soils planted with grapevines for a period of time between 2 and 32 years. Two studies were carried out in South Brazil: in the first study, soil samples, from 19 vineyards were collected and analyzed in the first 0.2 m depth-layer for the total and available Cu. In the second study, 3 soils were selected among the previous 19 according to the age of vineyard (5, 11, and 30 year-old), and their 0.60 m-depth profile was analyzed for 5 fractions of Cu (soluble, exchangeable, mineral, organic, and residual). All the soils were classified as Ultisols. The vineyards with more than 25 years under cultivation had a mean total Cu concentration of 90 mg kg−1 in the 0–0.10 m layer. Approximately 80% of it was potentially available to plants. The greatest total and available Cu were found in the soil surface layers (0.2 m depth), where up to 75% of the total Cu is adsorbed in clay minerals and only 20% is complexed in the OM.

Subperíodos fenológicos e ciclo da soja conforme grupos de maturidade e datas de semeadura

The objective of this work was to estimate the average length of phenological subperiods and of soybean development cycle as affected by maturity groups and sowing dates, and to determine the probability distribution functions that best characterize the distribution of this data. It was evaluated the exponential, gamma, lognormal, normal, and Weibull functions, and determined the one with the best fit to the simulated crop development data, using meteorological data collected from October 1968 to July 2012, at the main climatological station of Santa Maria, RS, Brazil. Crop development was simulated for different sowing dates, considering the maturity groups (GM): 5.9-6.8, early/semiearly cycle; 6.9-7.3, medium cycle; and 7.4-8.0, semilate/late cycle. The lognormal function has the best fit for the length of soybean subperiods and cycle. This length varies according to the sowing date, with bigger cycles in early sowings (October), and smaller ones at late sowings (December).

Soil Phosphorus Fractions in a Sandy Typic Hapludaft as Affected by Phosphorus Fertilization and Grapevine Cultivation Period

The purpose of this study was to quantify the phosphorus (P) fractions in phosphate-fertilized sandy soils under grapevines. Soil was sampled from a grassland site and two vineyards (13 and 31 years old) in the State Rio Grande do Sul, Brazil, from the layers 0–5, 5–10, 10–15, 15–20, and 20–40 cm deep. The samples were prepared and P fractions were assessed by chemical fractionation. Phosphate fertilization of the vineyard soils increased P contents to a depth of 40 cm, especially in the more recalcitrant fractions but detectable in the more labile fractions as well, which are plant available and may increase the risk of environmental contamination. Phosphate fertilizers and the period of grapevine cultivation had little effect on the levels of organic P forms, whereas cover crops in vineyards could be an appropriate strategy to increase or maintain the levels of soil organic matter and the levels of organic P over the years.

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.