Resumo em Inglês:

ABSTRACT The residue of imidazolinone herbicides in soil can be detrimental to soybean cultivation in rotation with Clearfield® rice. Thus, this research aimed to evaluate the ryegrass phytoremediation capacity on the imazapyr+imazapic residue in the soil in two soil moisture conditions in the off-season, and the effect on soybean growth in the next growing season. Two experiments were conducted between 2016 and 2017 in Santa Maria, Rio Grande do Sul state, Brazil. It was used the randomized block design in a 3 × 2 factorial. The first factor being the residue in the soil of 0, 210 and 420 g c.p.·ha–1 of the formulated mixture of the herbicides imazapyr+imazapic(525 + 175 g a.i.·kg–1) applied to rice in the 2015/2016 growing season, and the second factor being the presence or absence of ryegrass in the off-season. One experiment was conducted under soil moisture above 70% of field capacity in the off-season, and the other under ambient condition of soil moisture. The soil residue of the application of 420 g c.p.·ha–1 of the imazapyr+imazapic herbicides performed129 days before planting caused phytotoxicity and reduced dry matter of ryegrass under high soil moisture condition in the off-season in irrigated rice areas. Soybean, when planted 359 days after application, has its initial root and shoot growth affected by the residue of 210 and 420 g c.p.·ha–1 rates in high soil moisture condition in the off-season, regardless of ryegrass cultivation during the same period. However, grain yield is not affected.

Resumo em Inglês:

ABSTRACT Uptake of nutrients and cadmium (Cd) are dependent upon many factors, including plant species, ions concentration and pH. Tolerance to Cd-induced oxidative stress can be modulated by phytohormones such as abscisic acid (ABA), which induce the production of reactive oxygen species, activating proteins and enzymes involved in stress response and possibly stress tolerance. The present study aimed to evaluate the biochemical variations induced by Cd in ABA-deficient sitiens tomato mutant (sit) and its wild-type counterpart, Micro-Tom (MT), grown at different pH conditions. The plants were cultivated in nutrient solution (pH 5, 6 and 7; 20-days) and were then further grown over a 48-h period in 0 or 50 ?M CdCl2 at pH 6. Before Cd addition, the concentrations of nitrogen, sulfur, copper, iron and zinc were determined and variations in nutrients concentrations were observed. After Cd addition, sit roots grown at pH 5 and 7 did not exhibit differences in ascorbate peroxidase (APX) activity in 0 or 50 ?M CdCl2, and sit root grown at pH 6 exhibited lower glutathione reductase (GR) activity in the presence of Cd. Moreover, sit shoot grown at pH 5 showed decreased activities of superoxide dismutase (SOD), Mn-SOD II and Cu/Zn-SOD V, in 0 and 50 ?M CdCl2. The results indicated that pH modulates the plant nutrition in a complex way and may involve multiple ABA signaling pathways. Likewise, ABA status seems to be related with the Cd-translocation within the plant, suggesting that Cd, ABA and pH responses cannot be evaluated as isolated systems.

Resumo em Inglês:

ABSTRACT Eucalyptus globulus is one of the most commonly planted hardwood species for industrial use in various temperate regions around the world. The present study aimed to evaluate 62 full-sib families of E. globulus in one of the southernmost progeny trials of the species in the south of Chile. Estimates of genetic parameters for stem straightness, branching quality and growth traits were based on a Bayesian modelling approach using Gibbs sampling. A Bayes Factor (BF) analysis supported the hypothesis of significant additive genetic variation for all traits under study. Conversely, the BF supported a model with significant dominance effects for the diameter at breast height and stem volume, which explained up to 25% of the phenotypic variation. The greatest narrow-sense heritability estimates were found for the tree height and stem straightness, which were 0.15 (0.08 to 0.26) and 0.18 (0.10 to 0.28), respectively (mean of posterior distributions and 90% credible sets). In turn, the branching quality had a low heritability (narrow-sense) that varied from 0.05 to 0.10 (90% Bayesian credible region). The mean posterior estimate of genetic correlation between both quality traits was 0.22 (0.01 to 0.63, 90% credible set from a bi-trait threshold model), which indicates that stem straightness is positively related to branching quality. Our findings reveal that the study population responds to common patterns of breeding populations of E. globulus. This information is valuable for the development of improved seeds in the southern zone of Chile.

Resumo em Inglês:

ABSTRACT The aim of this study is to assess whether there is linear dependence between groups of morphoagronomic and bromatological traits in hybrid silage corn. Nineteen topcross hybrids and five checks were assessed in two different environments in Campos dos Goytacazes and Itaocara counties, Rio de Janeiro State, during the growing seasons 2013/2014. The study followed a randomized blocks design with four replicates. The phenotypic and canonical correlations between the groups of seven morphoagronomic and five bromatological traits were assessed. There is linear dependence between the group pairs of morphoagronomic, and bromatological variables. The morphoagronomic trait green mass yield can be adopted in indirect selection processes to indicate the increased bromatological quality of maize silage based on features such as crude protein, neutral detergent fiber, lignin, crude fat and mineral matter. Topcross hybrids UENF-2208 and UENF-2209 presented high potential for silage yield in the North and Northwest Regions.

Resumo em Inglês:

ABSTRACT Developing superior lines based on a simultaneous response from many traits of agronomic importance is a fundamental strategy to expand papaya cultivar supply, mainly the much-needed cultivars belonging to group Formosa. Our goal was to associate the pedigree method with REML/Blup procedure to select plants of progenies F2:3 with superior agronomic performance. The variance components and genetic parameters were estimated using REML approach, and the genetic values were predicted using Blup methodology. The combined selection was performed using the IG2 selection index based on weights associated with agronomic values to indicate the best progenies and lines. The heritability estimates of progeny mean were high in most traits and evidenced significant genetic variability between progenies. The narrow-sense individual heritability was moderate in traits such as commercial fruits and soluble solid contents, which indicates a favorable condition for selections within progenies. The index was consistent in the selection of six superior progenies according to the assessed traits. This index also enabled promising genetic gains in traits of great interest such as yield and pulp thickness. Although the progenies are derived from self generations, they proved to be superior in traits of significant importance such as yield, commercial fruits, and pulp thickness when compared to the Tainung-01 hybrid, which is a worldwide-planted cultivar used as a reference to Formosa representatives. Six lines were selected within the superior progenies to continue the Formosa group-lines development program. The association of the pedigree method with REML/Blup procedure can be useful to assist breeders in an autogamous breeding program.

Resumo em Inglês:

ABSTRACT The application of an adequate rate and splitting of nitrogen is essential for wheat grain yield and protein content. The aim of this work was to adjust nitrogen management approaches regarding agronomic performance and protein content of wheat cultivars in various environments. Field experiments were conducted under no-tillage system on soybean mulch during the 2011 and 2012 growing seasons in Londrina and Pato Branco regions. The experimental design was a randomized block in split plot with four replicates. Four wheat cultivars (IPR Catuara TM, BRS Gaivota, Quartzo, CD 120) were tested with six nitrogen (N) management forms. Were evaluated: number of ears per unit area (NEA); plant height (PH); thousand-kernel weight (TKW); test weight (TW); grain yield (GY); and protein content (PC). The combined ANOVA (p ? 0.01) and Tukey’s test (p ? 0.01) were used. The interaction between cultivars and environments influence all yield components, GY and PC. The interaction management forms of N and environments affected the TKW, NEA, GY and PC. The results showed that in low-rainfall environments, nitrogen topdressing could be suppressed with no negative effects on GY or PC. Under ideal weather conditions, the GY of wheat cultivars was enhanced on application of 60 kg.ha–1 N of urea at the beginning of tillering as well 20 kg.ha–1 of N at booting. Matching the appropriate cultivars to the ideal growth environment is essential for achieving high GY values. The nitrogen forms on the topdressing do not influence the PC of cultivars in Pato Branco.

Resumo em Inglês:

ABSTRACT Stalk rots compromise the translocation of water and nutrients, affecting grain filling. This study aimed to quantify the incidence of stalk rots in corn hybrids depending on sowing time and nitrogen topdressing rate, and to assess any correlation with grain yield. The experiment was conducted under field conditions in Atalanta, Santa Catarina state, Brazil, using a split-split-plot randomized block design. The hybrids AG 9025 PRO3 (super-early) and 30F53 VYH (early) were sown in the preferential (September 20) and late (December 5) sowing seasons with four nitrogen rates (0, 150, 300, and 450 kg·ha–1). The population density was 75,000 plants·ha–1 andthe nitrogen topdressing was carried out at the V4, V8, and V12 stages. The fungus Colletotrichum graminicola predominated in both hybrids and its presence was negatively correlated with stalk diameter and yield. The hybrid AG9025 PRO3 was more susceptible to stalk rot (35.1%) than the hybrid 30F53 VYH (8.8%). A higher incidence of stalk rot was observed in the late sowing season (31.1%) than in the preferential sowing season (11.2%). A decrease in the incidence of stalk rot was observed in the hybrid AG9025 PRO3 as nitrogen rates increased, but this behavior was not clearly observed in the hybrid 30F53 VYH.

Resumo em Inglês:

ABSTRACT Biochemical assays in a time-course were employed to evaluate stresses induced by glyphosate treatment in resistant and sensitive biotypes of Conyza bonariensis. Two experiments were conducted assessing glyphosate doses and time-course after treatment. The doses of glyphosate ranged from 0 to 11840 g ae·ha–1 and assessments performed until 552 h after glyphosate treatment (HAT). The objectives of this study were to evaluate the oxidative stress and differential antioxidant enzyme activity in glyphosate-resistant and -sensitive biotypes of hairy fleabane after glyphosate treatment. After treatment, both studied biotypes accumulated similar levels of shikimic-acid until 96 h. The sensitive biotype died at192 HAT. Shikimic-acid and hydrogen peroxide (H2O2) accumulation in glyphosate-resistant biotype were transient and did not differ from untreated plants at 288 and 500 HAT, respectively. In both glyphosate-resistant and -sensitive biotypes, a correlation analysis established a cause-and-effect relationship after glyphosate treatment, which leads to shikimic-acid and hydrogen peroxide accumulation, lipid peroxidation (indicates tissue damage) and an enhancement in the activity of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) enzyme. However, in the glyphosate-resistant biotype, the oxidative stress and tissue damage were lower, and antioxidant enzyme activities SOD, CAT, and APX were higher than in the -sensitive biotype. It indicates that antioxidant enzyme in glyphosate-resistant biotype might be related to the glyphosate-resistance process in Conyza bonariensis. This study is the first report of differential antioxidant enzyme activity in hairy fleabane.

Resumo em Inglês:

ABSTRACT Rosehip, Rosa canina L. fruit, is valued for its flavor, taste, color and aroma, in accordance with its recognition as one of richest sources of pro-health compounds. Screening, preservation and propagation of the most valuable local populations of rosehip are performed for food, pharmacological, and cosmetic applications. Eleven native R. canina genotypes from the Interior Aegean region, Turkey, were collected and analyzed regarding organic acids, phenolic compounds, sugars, and DPPH scavenging activity within this study. Regarding biochemical profile of fruits, protocatechuic acid and quercitrin were the most dominant compounds among 12 identified phenolics. The dominant organic acids were malic and citric and fructose and glucose were the dominant sugars. There was no correlation between DPPH scavenging activity and the analyzed chemicals in fruits. Although levels of certain compounds varied significantly between consecutive years, the ranking of genotypes according to the levels of particular chemicals was maintained. Generally, the most promising chemotype regarding biological value was 64US03. The chemical composition and the presence of bioactive compounds make the native to Interior Aegean R. canina genotypes a valuable source of bioactive agents preventing oxidative-stress related diseases.

Resumo em Inglês:

ABSTRACT The study of weed interference periods and the economic threshold level (ETL) of weeds on crops allows the adoption of management methods and the rationalized use of herbicides. The objective of this study was to determine the periods of interference and to test mathematical models to determine the economic threshold level of ryegrass in the wheat crop. Two experiments were carried out in a randomized block design with four replications. The first experiment was conducted in the 2014/2015 agricultural season. The periods of interference and control of ryegrass were studied in wheat. The periods of interference and/or control were: 0, 10, 20, 30, 40, 50 and 120 days after emergence (DAE). The second experiment was conducted in the 2016/2017 agricultural season. The ETLs were studied, being the treatments composed of wheat cultivars and 12 populations of ryegrass, in competition with the respective cultivars. The results allowed concluding that the management methods of weed ryegrass must be adopted in the period between 11 and 21 days after crop emergence, which is described as a critical period of control of this weed. The wheat grain yield loss competing with ryegrass reached 59% when grown with ryegrass. For ETL, the linear regression model of the rectangular hyperbola adequately estimates grain yield losses in the presence of ryegrass. The cultivar presenting the lowest values of ETL, that is, less capacity to live with the weed, was TBIO Alvorada. The other cultivars presented similar ETL values.

Resumo em Inglês:

ABSTRACT Considering the importance of blast, caused by Pyricularia oryzae, to impact wheat yield, this study investigated whether the foliar spray of potassium silicate (PS) could affect the photosynthesis of wheat plants and its potential to reduce disease symptoms. The Exp. 1 aimed to determine the effect of the foliar spray of PS on the photosynthetic performance of plants and was arranged in a completely randomized design with six treatments (plants sprayed with PS rates of 2.5, 5.0, 7.5, 10.0, and 12.5 g·L-1 at 35 days after emergence) and six replications. The leaf gas exchange (net CO2 assimilation rate (A), internal CO2 concentration (Ci), stomatal conductance to water vapor (gs), and transpiration rate (E)) as well as fluorescence of chlorophyll a (maximal photosystem II quantum yield (Fv/Fm), quantum yield of non-regulated energy dissipation [Y(NO)], photochemical yield [Y(II)], electron transport rate (ETR), and quenching non-photochemical [Y(NPQ)]) parameters were evaluated. The Exp. 2 was carried out to determine the effect of PS on blast control and also on the photosynthetic performance of plants. Plants at 35 days after emergence were sprayed with PS rate of 12.5 g·L-1, which did not affect photosynthesis on plants from Exp.1. This experiment was a 2 × 4 factorial and arranged in a completely randomized design with six replications. The factors studied were plants non-inoculated or inoculated plants and the spray of water, PS, fungicide (trifloxystrobin 10% + tebuconazole 20%; 0.75 L/ha), and fungicide + PS. There were no significant changes in the values of A, gs, E, Ci, Fv/Fm, Y(NO), Y(II), Y(NPQ), and ETR for plants sprayed three times (every 96 h interval) as the PS rates increased from 2.5 to 12.5 g·L-1. There was no significant relationship between the PS rates with either absorbance, reflectance or transmittance on the leaf blades. Linear regression model best described the foliar Si concentration-PS rates relationship. Foliar Si concentration significantly increased by 44 and 42%, respectively, for the PS and PS + fungicide treatments compared to water-sprayed plants. The area under disease progress curve was significantly lower by 64, 58, and 53%, respectively, for the fungicide, PS, and fungicide + PS treatments in comparison to water-sprayed plants. The photosynthetical process, primarily related to the Fv/Fm parameter, on wheat leaves was greatly impaired during the infection process of P. oryzae, but to a lesser extent on the leaves of PS-sprayed plants. In conclusion, the foliar spray of PS can be an environmentally friendly strategy to control wheat blast without causing perturbation to the photosynthetic machinery of wheat plants.

Resumo em Inglês:

ABSTRACT Although nickel (Ni) is recognized as plant nutrient since the turn of the 21st century, uncertainty remains about its optimum application rates and forms. This paper focuses on Ni application in soils, relating to its effect as a plant micronutrient. Specifically, the effect of Ni on the activity of urease in soybean plants is examined. The effects of applying four Ni rates in two different soil types were tested. A full factorial 2 × 4 blocked design experiment was established under controlled conditions. Ni rates (0, 0.25, 0.5 and1.0 mg of Ni·kg–1 of soil) were applied in two soils with contrasting clay contents. The addition of Ni increased the urease activity in soybean plants but was affected by soil textural differences. The highest urease activity was achieved by the application of 1.0 mg·kg–1 Ni in the sandy soil. The absorption of Ni by the plants and its availability was found to be soil texture dependent. The rate of 0.25 mg·kg–1 Ni increased the soybean dry matter production by 25% in the sandy soil. In conclusion, Ni was effective in promoting plant growth and biomass accumulation although depending on soil clay proportion. For soybean, there was no correlation between urease activity and biomass accumulation. The results of this study indicate a clear Ni effect in different type of soils in São Paulo state, serving as a solid initial doses indicator for soybean fertilization programs and future studies on nickel in Soybean.

Resumo em Inglês:

ABSTRACT The normalized dispersion index (NDI) and the b/a index are commonly used to express the stability of aggregates measured by ultrasound. However, few studies have used the critical energy (CE) extracted from modeling to explain the effects of soil use and management on soil aggregation. The objective of this study was to evaluate the influence of soil cover on the CE level required for dispersion of aggregates of a Typic Hapludalf. Soil samples collected from the 0.0-0.05 m depth were evaluated in five different managements with cover plants: perennial soybean (PS), peanuts (P), spontaneous vegetation (SV), black oat/forage turnip (BOFT), and black oat/hairy vetch (BOHV). Aggregates ? 2 mm of the treatments were exposed to ultrasonic irradiation during 0, 30, 60, 120 and 180 s. The specific applied energies were calculated based on sonification time and potency: 0, 745, 1490, 2980, and 4470 J·g–1. After each sonification, sand (2000-53 ?m), silt (53-2 ?m) and clay (< 2 ?m) were quantified. The mass of aggregates of each size class was modeled as a function of the ultrasonic energy. The CE, the NDI and the b/a indexes were coefficients extracted from these models. Cover crops influenced the critical energy levels required for dispersion of aggregates of the Typic Hapludalf. However, our methodology did not prove management systems with intercrops of the cover crops, as black oats and vetch, contribute more effectively to the increase of soil aggregation.

Resumo em Inglês:

ABSTRACT Residual biomass from grains has potential as an energetic source. Biomass composition determines this potential and is related to plant nutrition, which may vary according to soil fertility. The aim of this 23-year field study was to evaluate changes in chemical attributes of a Brazilian Oxisol and in the energetic potential of oat (Avena sativa L.) and soybean (Glycine max (L.) Merr) residual biomasses provided by tillage systems and fertilizer rates. The trial was performed since 1989, assessing soil chemical attributes in no-tillage (NT), conventional (CT), minimum (MT) and no-tillage plus chisel plough (NT+CP), with two fertilizer rates (normal and reduced, since 1994). Oat and soybean (2012/2013) residual biomasses were collected and analyzed by its elemental composition, higher heating value (HHV) and theoretical potential for electricity production. The NT system presented higher P-resin availability; NT and NT+CP provided higher OM and total P content on soil surface. Without appropriate amounts of K and P fertilizer, P-resin and P total contents diminished mainly in 0-0.1 m depth, while exchangeable, non-exchangeable and total K+ fractions were mined even in deeper layers (0-0.3 m). The better general fertility conditions were achieved by conservative tillage systems, with normal fertilizer rate. Soil fertility levels changed chemical composition of both biomasses but had no effect on biomass HHV. Considering a system with oat and soybean grain production plus residual biomasses for energetic exploitation, it could be possible to generate 2,941 GWh·year–1, while still achieving 70% residue coverage under no-tillage maintenance.

Resumo em Inglês:

ABSTRACT This study evaluated the cycle duration, physicochemical characteristics of fruits and climatic adaptation of the ‘SR 501-17’ hybrid grape grafted on four rootstocks for the production of white wine. We tested four rootstocks, ‘IAC 766 Campinas’, ‘IAC 572 Jales’, ‘IAC 571-6 Jundiaí’ and ‘IAC 313 Tropical’, planted in two climatic regions, Cfa and Aw, in the state of São Paulo, Brazil in the cultivation years 2014 and 2015. Cycle duration, production, cluster weight, number of berries per bunch, content of soluble solids, titratable acidity, a maturation index and the weight, length and width of berries were evaluated. A principal component analysis characterized the cultivar for both climatic regions and years. The rootstock did not influence the cycle, production or physicochemical characteristics of the ‘SR 501-17’ hybrid. The soluble-solid content in the must was higher and the production cycle in 2014 was longer for the Cfa climate. The production cycle was shorter and the weight and width of the berries were lower, mainly in 2015, for the Aw climate. The cycle was thus longer, production was higher and the chemical characteristics were better for the ‘SR 501-17’ hybrid under Cfa conditions, regardless of the rootstock.