Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The isolates were obtained from vegetal tissue, phylloplane-rhyzoplane of tomato and soil in the growing region of Rio Grande do Sul. “In vitro” tests were based in the method of paired crops culture, in the production of volatile compounds and growth in culture media containing fungicide. “In vivo” tests measured the efficiency of the two most efficient isolates selected by “in vitro” experiments through the evaluation of the incidence of Botrytis cinerea in tomato flowers under different forms of application. Gliocadium viride led to a 62% reduction and was considered a promising alternative for the biological control of B. cinerea. This result was similar to that obtained through the test of paired crops ran under laboratory conditions. In this test, the efficiency of G. viride was 58.14%. Trichoderma harzianum did not differ significantly from the control treatment.

Soil chemical attibutes were assessed after nine years on a typical Dystrophic Red Latosol located in Passo Fundo, State of Rio Grande do Sul, Brazil. Four soil management systems – 1) no-tillage, 2) minimum tillage, 3) conventional tillage using a disk plow followed by use of a disk harrow, and 4) conventional tillage using a moldboard plow followed by use of a disk harrow – and three crop rotation systems [I (wheat/soybean), II (wheat/soybean and common vetch/corn), and III (wheat/soybean, common vetch/corn, and white oat/soybean)] were evaluated. In November 2001 after winter crops were harvested compound soil samples were collected at the following depths (cm): 0-5, 5-10, 10-15, and 15-20. A randomized complete block design, with split- plots and three replicates, was used. The main field plots (4 x 90 m) were formed by soil management systems, while the subplots (4 x 10 m) consisted of crop rotation systems. The values of pH and concentration of extractable P, and exchangeable K was affected by soil management. Higher contents of soil organic matter, extractable P, and exchangeable K were observed in the 0-5 cm layer for the conservation tillage systems (minimum tillage and no-tillage), as compared to the conventional tillage systems (disk plow and mold- board plow). The values of soil organic matter, P, and K were higher in the 0-5 cm layer, when compared to the ones observed in the 15-20 cm layer, in all soil management and cropping systems, while the opposite occurred with pH. Soil acidification was detected under both conservation tillage systems. The yield of white oat, wheat and soybean grown under no-tillage and minimum tillage was were than the yield obtained for white oat, wheat and soybean after conventional tillage systems (disk plow and moldboard plow). The lowest soybean and wheat yield obtained in monoculture.

The strawberry plant is cultivated in Rio Grande do Sul predominantly in small properties, for consumption in natura and industrial. This study aimed to isolate and to select fungi possibly antagonist towards the pathogens, to identify the occurring patho gens and to determine in vitro the antagonistic action to the pathogens. The filamentous fungi from the soil, epiphytes and endophytes from strawberry trees have been isolated, in three crops under ecological management, in the cities of Feliz and Alto Feliz. Soil, leaves and flowers of plants without symptoms of diseases have been collected, monthly, from April to November of 2002. The following species have been identified: Alternaria alternata, Aspergillus niger, Athelia sp., Cladosporium cladosporioides, Epicoccum purpu rascens, Fusarium sp., Gliocladium roseum, Paecilomyces variotti, Penicillium commune, Phomopsis obscurans, Torula sp., Tricho derma harzianum, Trichoderma koningii, Trichoderma viride, Xylaria sp. In vitro tests have showed antagonistic activity of T. harzi anum and T. koningii to A. alternata and P. obscurans; P. variotti has been antagonic to A. alternata. 

It was determined annual and seasonal regimen of chilling hours below 7oC and 10oC in different climatic regions, in Rio Grande do Sul State, Brazil, between years of 1956 and 2003. The annual chilling hours varied from 121 hours in region of Baixo Vale do Uruguai, to 487 hours in Planalto Superior – Serra do Nordeste for temperature below 7°C. For temperature below 10°C, annual regimen of chilling hours varied from 387 hours to 1114 hours, respectively, in the same regions. In the winter, the chilling regimen varied from 100 to 337 hours for temperature below 7oC, and from 296 to 682 hours for temperature below 10oC, respectively in the regions of Baixo Vale do Uruguai anda Planalto Superior – Serra do Nordeste. The comparative results of autumn and spring, show similar regimen of chilling hours in different regions. In the summer, were verified low values of chilling hours, and only for temperature below 10°C. 

Inadequated soil tillage can induce the formation of compacted layer near soil surface. Soil physical attributes were assessed after sixteen years of distinct soil management on a typical dystrophic red latosol located in Passo Fundo, Rio Grande do Sul State, Brazil. Four soil tillage systems – no-tillage, minimum tillage, conventional tillage using a disk plow plus disk harrow, and conventional tillage using a moldboard plow plus disk harrow – and three crop rotation systems - system I (wheat/soybean), system II (wheat/soybean and common vetch/corn), and system III (wheat/soybean, white oat/soybean, and common vetch/corn) were evaluated. A randomized complete block design, with split-plots and three replicates, was used. The main plots were soil tillage systems, while the split consisted of crop rotation systems. Soil cores were also collected in a fragment of subtropical forest adjacent to the experiment. No-tillage showed higher soil density than conventional tillage using a moldboard plow plus disk harrow, minimum tillage, and subtropical forest. The subtropical forest showed the highest total porosity and macroporosity, as compared to the all soil tillage systems and crop rotation systems, and the lowest bulk density and microporosity. Soil bulk density was increased from the top layer (0-5 cm) to deeper layer (10-15 cm) in all soil tillage systems and rotation systems and presented the lowest total porosity and macroporosity.

In order to evaluate the effect of ethephon on the anticipation and decrease of picking number throughout the course of harvest time of ‘Irati’ plum, an assay was conducted on the Centro de Pesquisa da Região da Serra - FEPAGRO SERRA, in Veranópolis, RS, Brazil. The statistical design was entirely randomized, in a factorial design 2 x 4 x 5, in which ethephon was applied in two dates and four concentrations. Ethephon was sprayed directly on the fruits, till they dropped, with a portable pulverizer. The application of ethephon eight days before harvest beginning resulted in higher amount of fruit in the first picking compared to the application four days before harvest beginning. In both time of spraying with ethephon the amount of fruits harvested in first and second picking together was approximately 80% of the total. In the first picking, the fruit harvest was higher when they were sprayed with ethephon, without significant statistical difference among concentrations. The average fruit weight was higher in the control treatment, 120 mg/l and 240 mg/l and in the two first picking.

Thirty three Rhizobium sp isolates obtained from birdsfoot trefoil (Lotus corniculatus L.) collected on different regions of Rio Grande do Sul were characterized using Box-PCR. The isolates presented distinct amplification profiles among then, as well as from the isolates recommended nowadays for the production of birdsfoot trefoil inoculants, SEMIA 806 and SEMIA 816. The genetic similarity index, determined by the Jaccard coefficient, ranged from 0.5 to 0.9%, pointing out to a large genetic variability among the isolates. The cluster analysis isolates showed a formation of tree large groups and was not possible to establish a relationship among the amplification profiles, groups formed and geographic origin of the isolates.

The preservation of natural pastures is important to Rio Grande do Sul because, in addition to its economic value, it has ecological implications. Inadequate or poor management of native pasture can cause an increase in frequency of undesirable native species. Undesirable species can decrease production from pastures, through competition with desirable forage species, or by directly affecting livestock production through reduced intake, or even through toxic effects. Undesirable species, from the animal production point of view, most frequently found in Rio Grande do Sul, are caraguatá (Eryngium horridum Malme), carque- ja (Baccharis trimera Less.), chirca (Eupatorium buniifolium Hook.), mio-mio (Baccharis coridifolia DC.) and alecrim (Vernonia nudiflora Less.). Some strategies to control these species include mechanical control, by mowing or dragging iron shanks; chemi- cal control, by herbicides; biological control, by grazing, as well as other management strategies (e.g., fertilization) that could favor native pasture in intraspecific competition. Some of these interventions influence vegetation dynamics, such as grazing and burning. Obviously, the efficacy of all these methods depends on morphological and phenological characteristics, which vary among species. Therefore, it is important to implement the management strategy during the right utilization period. Experiences show that interaction between methods can promote greater efficiency upon species control. The aim of this review is to aggregate the information about undesirable native plants in Rio Grande do Sul and methods for their control.

The objective of this study was to assess the soil fertility on a typical dystrophic Red Latosol (Typic Haplorthox) located in Passo Fundo, State of Rio Grande do Sul, Brazil, ten years after the introduction of mixed production systems, using production systems integrating grain production with pastures under no-tillage. Four production systems were evaluated: system I (wheat/soybean, white oat/soybean, and common vetch/corn); system II (wheat/soybean, white oat/soybean, and grazed black oat + grazed common vetch/corn); system III [perennial-cool season pastures (fescue + white clover + red clover + birdsfoot trefoil)]; system IV [perennial-warm season pastures (bahiagrass + black oat + rye grass + white clover + red clover + birdsfoot trefoil)]; and system V (alfalfa as hay crop), which was established in an adjacent area in 1994. The areas under systems III, IV, and V returned to system I after the summer of 1996. The systems I, II, III, IV e V increased the soil contents of organic matter, extractable P, and exchangeable K, mainly at 0-5 cm depth. The systems I, II, III, IV e V organic matter, exchangeable Al, extractable P, and exchangeable K levels decreased from the 0-5 cm layer to the 20-30 cm layer, while the opposite occurred with pH and exchangeable Ca and Mg contents.

Vegetal residues in anaerobic decomposition in irrigated farmings of rice produce organic acids, such as, acetic, propionic, butiric, formic, vanilic, which affect the establishment of seedlings. Therefore the present work had for objective to analyze the physiological quality of seeds and bioquimical activity of rice BR IRGA-409 seedlings, treated with several concen- trations (zero; 1; 2; 4; 8 and 16 ml/L) of acetic and propionic acids. In order to performer this some assay were conducted such as: tests of vigor (first count, electrical conductivity, emergency speed index and emergency), chemical composition (starch, total soluble sugars and protein contents), determinations of the activity of α-amylase and fosfatase acid, and measurements of growth (chlorophyll concentration and leaf area). The regression analysis showed that the germination, emergency speed index, the emer- gency of seedlings and the electric conductivity were significantly affected with the increase in the concentrations of acid. Starch, total soluble sugars and protein contents were reduced on higher concentrations (≥8 ml/L) for both acids. The total activity of α-amylase was more enhanced by acetic acid than propionic acid, while the activity of phosfatase-acid was not modified. The chlorophyll contents and leaf area decreased with increment on concentrations of acetic and propionic acids.