Repositório RCAAP

The objective of this study was to evaluate the effect of three methods of soil tillage (conventional, reduced and no-tillage), three crop systems (oats/ com, oats + clover/ com, and oats + clover/ com + cowpea) and two rates of nitrogen (0 and 120 kg/ha) on the accumulation of crop residues on the soil surface, com nutrition and yield. The accumulated crop residues on the soil surface, evaluated at the end of the year, varied from 3.09 to 5.60 t/ha of dry matter, and it was not affected by soil tillage, crop systems and N rates. The nitrogen was the most limiting nutrient to the com yield, and its availability was lower in no-till lago, as compared with conventional tillage. However the com yield was not affected by tillage methods and it varied from 2.39 to 5.72 t/ha. Without N application, use of legumes as green manure-cover crops increased com yield up to 81% and it was correlated with total amounts of N in the biomass on the soil surface (residues plus winter crops). The conservation management systems, that associate no-tillage or reduced tillage, and legumes for cover and N addition, resulted in relatively high com yields. In addition, they have benefits due to soil cover crop residues during a larger period of the year, compared with conventional soil management systems.

Among bacterial diseases that affect dry beans, common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli, can considerably reduce grain yield of this crop and is the most important in Brazil. Genetic resistance is one important characteristic to be considered in the integrated disease management during the development of new dry bean cultivars. The objective of the present research was to obtain dry bean lines resistant to common bacterial blight using the single seed descent method. Thirty lines resistant to common bacterial blight were obtained with considerable reduction in generation advance time.

Seed germination is basic to good pasture implantation. The objective of this work was to evaluate germination ability of Paspalum notatum Flügge var. notatum seeds, ecotype André da Rocha, under distinct storage conditions: storage at 5° C in refrigerator, or in laboratory conditions. Sceds were submitted to the standard germination test and two methodologies to break dormancy: 1) imbibition in potassium nitrate (0,2 %); 2) manual scarification of the caryopsis. A split-plot experimental design was used with four replications of 50 seeds, for each storage condition and treatment. Storage conditions were treated as plots, and treatments as subplots. There were no differences in seed germination, regarding storage conditions and treatments to break dormancy (P>0,05). The KNO 3 treatment was the most efficient in breaking dormancy of seeds.

The objective of this study was to evaluate the efficiency of baits formulated with boric acid to control Sarasinula linguaeformis (Semper, 1885) (Mollusca, Veronicellidae). The trial, in randomized complete design with nine treatments and five replications, was carried out in laboratory of Centro de Pesquisa para Pequenas Propriedades, EPAGRI (Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina), Chapecó, westem Santa Catarina, Brazil. Each plot consisted of three slugs inside boxes (gearbox). The treatments, baits formulated with a mix of boric acid (different percents), wheat and com flour and eggs, were efficient in the attractiveness and control of the slugs, mainly at the rates of 2,0; 3,0; 5,0 and 10,0 %, with mortality between 99,46 and 100 %, up to 72 hours after the baits supply.

The mito Dichopelmus notus (Acari, Eriophyidae) causes tan and fali of leaves in mate tree. The treatments: canopy thirds (upper, medium and lower) and depth inside canopy (internal and external) were arranged in randomized blocks with a factorial design, with ten replications (trees), and were performed in an orchard in Chapecó, Santa Catarina to propose a sampling plan for Dichopelmus. Each plot consisted of one tree. Samples of three leaves per treatment were collected every two weeks from February through May 1999, per treatment. The number of mites/1 cm2 of each leaf was counted at laboratory. Through the modal, an estimator of the overall mean variance and the variances associated with random effects was obtained. The number of trees (10 and the number of leaves (L) were obtained by the combination of KxL, timing the variance of the mean at a minimum level. Results indicate that it is necessary to examine three internal leaves from inferior or medium thirds on a minimum of 110 trees.

The soil microbial biomass is of paramount importance for the understanding of the organic matter combover, nutrient cycling and energy flux in the soil. The most widespread and correlated methods are direct microscopy for fluorescent stained microorganisms (Biovolume), the chemical methods (ATP=adenosine triphosphate and fumigation-extraction—FE), and the physiological methods (fumigation-incubation=FI and substrate induced respiration—SIR). The biovolume method is rather subjective and time consuming, while the chemical and physiological methods are of better reproducibility and applied to a wider range of soils. For lowland soils, the methods tested are basically the same as for upland soils. The data available show that the FE and modified versions of Fl and SIR have a satisfactory performance, but the original ATP method seems to be unsuitable. The expression usually found in the literature does not refer to the total microbial biomass, but rather to specific components of the biomass I like C, N and ninhydrin reactive nitrogen. For the forthcoming years, significant increase in research is expected involving ATP, SIR, Fl and FE methods in organic matter turnover and energy cycling. The flourishing methods for biomass assessment of particular groups of microorganisms as well as the molecular techniques for the identification of individual components of the biomass are also expected to become more popular.

Virulence of 24 strains of Pasteurella multocida, 13 isolated from pleuritic and pneumonic pig lungs, and 11 from pig lungs obtained from abattoirs was studied. P multocida was cultured in BHI medium incubated at 37° C for 18 h and the number of colony forming units (C FU/ml) determined by inoculation of decimal dilutions on blood agar plates. Dilutions from 10 4 to 10.13 (8,3 x 10 15 to 1 CFU) were inoculated intraperitoneally in mice and the number of deaths for each dilution determined over a 7-day period. Each inoculated strain was recovered from at least two mice. LD50 were determined by the Spearman- Kãrber method. It was observed a wide variation in LD50, ranging from <1 to 10 10.2 CFU. There was no difference in virulence among strains from clinical cases or from abattoir lungs.

The high sensibility of maize crops to water deficits, mainly during the flowering period, makes necessary precise data in terms of water necessity, for several purposes of applications. With the objective to quantify the evapotranspiration throughout the maize crop cycle, at different atmospheric conditions, a field experiment was carried out from 1993/94 to 1996/97, at the Estação Experimental Agronômica of UFRGS, in Eldorado do Sul, Brazil. It was used an early hybrid (Pioneer 3230), sowed at the end of October, in a stand of around 67 thousands plants per hectare. The crop maize maximum evapotranspiration was measured in a weighing lysimeter, located in the center of a 0,54ha homogeneously cropped area. An average ETm of 656mm for the entire crop cycle was obtained, ranging from 575 to 732mm during the four-years period. This variation was attributed, mainly, to differences in the atmospheric evaporative demand. Variations in ETm throughout the crop cycle were also observed in a similar pattern, with minimum values at the beginning of the plant growth, increasing according to the leaf area index, up to maximum values during the flowering stages, and decreasing at the end of the crop cycle. 

 A study was conducted in greenhouse to evaluate the effect of different flooding periods on water utilization, nutrient uptake, and growth of the soybean plant in a soil of Guaiba series (Ultisol). The treatments consisted in flooding for 5, 10, 20, and 26 days, started when the plants presented three developed trifoliolate leaves, and compared to the soil water content at the field capacity. The treatment of flooding for 26 days ended when the plants showed the first flower. Soybean water consumption per unit of dry matter weight increased with the flooding duration, reducing the efficiency of water usage by the plants. Flooding reduced the water intake, dry matter weight, and plant height as well. The amount of roots increased due to the secondary root development, a reaction to low oxygen availability in the flooding condition. The P, K, Ca, Mg, and Mn content in the plant tissue decreased with the flood duration, whereas high Fe content was detected as a result of flood until the beginning of flowering. 

This research was carried out in a citrus nursery of orange 'Valência' to study the effect of products to control the citrus leafminer, Phyllocnistis citrella. The products (active ingredient) and amounts of commercial product/100 I water, were: imidachloprid (150 g), Bacillus thuringiensis (200 g), lufenuron (75 ml), abamectin + mineral oil (25 ml + 250 ml), fention (100 ml), and a check. The statistical design was a randomized block, with six treatments and four replications. Each treatment consisted of 20 plants (five in each block), and 10 leaves per plant were collected. The treatments were evaluated 7 and 14 days afta product application. The most efficient products were: imidachloprid, lufenuron and abamectin + mineral oil; Bacillus thuringiensis presented moderate control and fention was not efficient.

The experiment started in 1987 and finished in 1.990; was carried out at Estação Experimental Agronômica, Universidade federal do Rio Grande do Sul, located in Eldorado do Sul, Rio Grande do Sul —Brazil (30° 05' S, 5l"40' W). The orchard was established in 1976 and the main objective of the experiment was to evaluate fruit yield and quality of 'Valência' orange submitted to six spray fertilization treatments, with ultimate suppression of magnesium, manganese, zinc and boron. The experimental design was in randomized blocks, with five replications. Results did not show any effect on fruit yield, but there were significant effects on fruit quality. The fertilization increased the concentration of boron, manganese, and zinc in the leaaves.

The effect of Brachiaria brizantha on leaf arca and biomass production of Eucalyptus citriodora and E. grandisseedlings, grown in soils with different water contents, was evaluated under greenhouse conditions. Treatments were arrangedin factorial design, with four replications (2x3x4): two species of eucalyptus (E. citriodora and E. grandis), three watercontents (20, 23 and 26% mass), and four B. brizantha populations (0, 1, 2, 3 plants per pot). Moisture content in the potswas maintained constant until experiment harvest, 70 days after seedlings transplanting. B. brizantha showed a negativeinfluente on E. citriodora and E. grandis seedlings developent, when grown in the three water contents. However, there wasa higher effect when growth was under the best water conditions (26%), especially in presence of two to three plants of B.brizantha. E. citriodora was more sensitive to the interaction of water content and B. brizantha populations.

Presence of native forest showed a detrimental effect on the colonization and distribution of Anastrepha fraterculus (Wied.) adults in apple (Malus domestica) orchard but not in the peach (Prunus persicae) orchard. In apple, adults began to occupy the orchard in arcas adjacent to the forest, and concentrated its presence in the forest and surroundings. In peach, 90.5% of the flies were captured within the orchard, and only 0.5% in the forest or nearby. Within the apple orchard, 43.0% of the flies were captured, and the first flies invading the habitat were females, while in peach both sexes occurred simultaneously, especially females. It was possible to characterize a pattem of adult colonization and distribution in peach and apple agroecosystems. In peach, fruit presence (especially dose to ripening) had a positive correlation with adult occurrence and distribution, while in apple this did not occur.

Important contribution for oat genetic improvement is the possibility to use mechanisms that increase geneticvariability. The objective of this work was to evaluate and compare the sensibility of hexaploid oat fixed genotypes as aresponse to the employment of mutagenic agents. Two mutagenic chemicals, ethyl methanesulphonate (EMS) and methylmethanesulphonate (MMS), and one physical (gamma rays), in three doses, were tested in four genotypes. The experimentaldesign was a randomized complete block with three replicates for each treatment, where the experimental unit was composedby a gerbox with germitest paper and 100 seeds. Averages were compared by the Scheffé test. Data indicate linear decrease ofthe characters germination and root length with the increase of the mutagenic dose. Only the linear effect of mutagenic EMSwas significant. Within the studied interval (0-3%), germination decreased (b= -1,03) with the increase of the EMS doses.Gamma radiation caused significant reduction in root length (b = -4,72), as compared to the other mutagenic agents.

The climatic variability is a risk factor to agricultural activities. In Southem Brazil the main climatic risks forwheat production are frost at anthesis and excess rainfall at harvest time. This study of climatic risks zoning integratestechniques of crop modeling and simulation with geoprocessing tools in order to indicate the areas with lower risks for wheatcrop in Rio Grande do Sul, for each sowing period. The analysis of the risk maps shows that there is variability of climatic risksfor wheat growing in the State, according to the region and sowing period. The combination risk of frost at anthesis with riskof excess rainfall at harvest was used to define, for each County, the wheat sowing period of minimum risk, where the risk oflosses, due to the climatic factors studied, remained bellow the high risk range in 80% of the years.

Red rice (Oryza saliva L.) is considered the most serious weed in rice crop in Rio Grande do Sul. Severaltechniques are employed to decrease its infestations on irrigated rice, among them, the use of minimum tillage. The objectiveof this research was to evaluate the effects of red rice chemical management on grain yield and agronomic characteristics ofirrigated rice in minimum tillage system, as well as to define the time in which such management can be performed. To reach thispurpose, a field experiment was conducted in 1996/97, with the following treatments: red rice desiccation periods (10, 6, and2 days before, and 2 days after rice sowing), non-selective herbicidas (sulfosate, at rates of 825 and 1650 g/ha, and paraquat at400 g/ha), plus controls without herbicide application (with and without start nitrogen fertilization), and systems of irrigatedrice sowing (in presence and in absence of red rice residues). The results showed that the presence of rice residues interferednegatively on grain yield of rice, especially when sowing occurred dose to herbicide application. Sulfosate, especially at thelow rate, caused reductions in most of the parameters evaluated.

Oryzophagus oryzae, the rice water weevil (RWW), an important insect pest in irrigated rice crop in Brazil, can reduce 10 to 30% the grain yield. The purpose of this study was to compare the efficiency of RWW chemical control by seed treatment, foliar spray or rice irrigation water treatment, using the more appropriated active ingredients, formulations and rates, to each insecticide application method. The seed treatment with carbossulfan TS (300 g/100 kg) or fipronil FS (50 and 75 g/100 kg), and foliar spray with fipronil WDG (60 and 80 g/ha), or lambdacyalothrin (10 glha)provided high larval control (92 to 99%) and avoided grain yield reduction (18 to 25%), equivalent to standard control method, based on carbofuran G (750 g/ha) applied directly on rice irrigation water. Fipronil G (60 and 80 g/ha) was significantly less efficient than granulated carbofuran. It was concluded that seed treatment and foliar spray, according to active ingredients used, are more efficient for RWW control than granular carbofuran applied directly on irrigation water.

The agronomic performance of ten Desmodium genotypes was evaluated in a trial carried out at Porto Velho,Rondonia. The experimental design was a radomized complete block with three replications. The following genotypes wereevaluated: five of D. ovalifolium (CIAT-350, CIAT-3666, CIAT-3673, CIAT-3774, and CIAT-3784), four of D. heterophilum(CIAT-349, CIAT-365, CIAT-3782, and CIAT-3791), and one of D. canum (CIAT-3522). During the rainy season, thegenotypes D. ovalifolium CIAT-350, CIAT-3784 and D. canum CIAT-3522 presented higher dry matter (DM) yields. Duringthe dry season, D. ovalifolium CIAT-3673, CIAT-350 and D. canum CIAT-3522 were the most productive genotypes. Thehighest crude protein contents were obtained by the genotypes D. heterophilum CIAT-349 and CIAT-365, which did not differfrom D. ovalifolium CIAT-3673. The genotypes of D. ovalifolium CIAT-3673, CIAT-350, and CIAT-3784 had higher phosphoruscontents. The highest calcium and magnesium contents were provided by D. ovalifolium CIAT-350 and D. heterophilumCIAT-3791, respectively, while higher potassium contents were obtained by D. canum CIAT-3522, D. heterophilum CIAT-3791 and D. ovalifolium CIAT-3774 genotypes. The higher in vitro dry matter digestibility coefficients were provided by D.heterophilum CIAT-3782 (50,3%), CIAT-349 (48,2%) and CIAT-3791 (47,7%). The most promising genotypes to obtainhigher forage yields with.better quality, were D. ovalifolium CIAT-350, CIAT-3673, and D. canum CIAT-3522.

Soil spatial variability of acidity factors (pH, Ca, Mg, Ca+Mg, AI, H+Al, sum of bases, cation exchangecapacity, and bases saturation) was studied in different soils and management systems, at two regions of Rio Grande do Sul -Brazil a) Eldorado do Sul, on a dark red podzolic soil, Kandiudult (conventional tillage, no-tillage, and chisel plow, in plots ofa soil management trial, and pasture), using a grid sampling of 1 x 1 m at the depths of 0-0,05 and 0,05-0,20 m; b) Passo Fundo,on a dusky red latosol, Hapludox (conventional tillage and no-tillage), and a dark red latosol, Hapludox (pasture), in agriculturalfarms, using a grid sampling of 10 x 10 m at the depths of 0-0,10, 0,10-0,20, and 0,20-0,30 m. Wheat yield variability wasstudied only in Passo Fundo by harvesting areas of 1 m 2 , at the same grid sampling. Soil properties followed a normaldistribution, in most of management systems and dephts. The lowest variability, evaluated by coefficients of variation, wasfound for pH and cation exchange capacity (CVs<10%), and the highest for Al (CVs>40%), with other properties placingintermediary position (10%<CV5 <40%). Among cultivated areas, no-tillage exhibited greater coefficients of variation, followedby minimum tillage and conventional tillage. Spatial correlation was found for pH, H+Al, and bases saturation in Eldorado doSul, whereas in Passo Fundo was found for all soil properties (with exception to H+Al and cation exchange capacity, inpasture) and for wheat yield on the management systems studied. No-tillage exhibited positive cross-correlation for wheatyield with Ca, with Mg, with Ca+Mg, with sum of bases, and with cation exchange capacity.

The objective of this work was to study the distribution of the statistics coefficient of variation (CV) and minimum significam difference (MSD) as a way to obtain the limits for quality control, in competition experiments of maize, rice, soybean, wheat, beans, barley, oat, triticale and sorghum. Data of 2017 cultivar competition assays, conducted in the state of Rio Grande do Sul, Brazil, from 1987 through 1995 were included. The CV and MSD values were submitted to the Lilliefors test. The class limits of these statistics were established based on the averages and variante of the variables tested. Using the analogous management criteria for conduction of the experiments, each assay was dismembered for each crop evaluated. We concluded that the diversity of management procedures employed in cultivar competition experiments adversely affects their quality control. This control must be performed according to the crop and management employed. No information is lost when CV and MSD classified as too high are disregarded.