Volume 29, Number 2, 2005

The evaluation of agronomic instrumentation to determine soil water content is very important for scientific research. Regardless of the technique in use, it is important that the soil water content is determined easily and quickly for the determination of the function K(q), e.g. With the objective of comparing the performance of the equipments neutron probe and TDR with a tensiometer at determining variations in the soil water content and the values of soil hydraulic conductivity obtained from the soil water […]

Field experiments involving soils require previous verification of the soil spatial variability. The objective of this research was to study the spatial variability of soil physical properties of an experimental plot using geostatistics. The experiment was conducted in 1982 at the Experimental Center of the Instituto Agronômico in Campinas, state of São Paulo, Brazil, on a Red Latosol (Rhodic Ustox) under conventional tillage in a 30 x 30 m area, with sampling points arranged in a 5 m square grid. The analyzed properties were […]

This study was carried out to verify the occurrence and genetic diversity of diazotrophic bacteria associated to the native graminaceus plants Elyonurus muticus (Carona grass) and Axonopus purpusii (Mimoso grass) and the exotic Brachiaria humidicola (Brachiaria) that form the pastures in the Nhecolândia region of the Pantanal in the state of Mato Grosso do Sul, Brazil. The plants were harvested in the dry and rainy seasons and the diazotrophic bacteria populations in the soil and on roots and leaves of […]

Anthropogenic disturbances have resulted in an increased threat of extinction of many native orchid taxa in Brazil’s Atlantic rain forest. In nature, orchids utilize mycorrhizal fungi to initiate seed germination and seedling development, at least in the early stages of their life cycle. Mycorrhizal fungi associated with the roots of orchids have thus been isolated, characterized and stored as important resources for a future conservation program of orchid species through symbiotic seed germination. Three mycorrhizal Rhizoctonia-like fungi were isolated from […]

Symbiotic in vitro seed germination and protocorm development of Oncidium flexuosum is described for the first time. O. flexuosum seeds were inoculated with ten mycorrhizal isolates, originally obtained from the mycorrhiza of ten neotropical Brazilian orchid species, including O. flexuosum. One of the isolates belongs to Epulorhiza repens, two to Epulorhiza epiphytica, six to Ceratorhiza spp., and one to Rhizoctonia sp. Seeds inoculated with the M2 isolate of Ceratorhiza sp., originally isolated from the root system of wild O. flexuosum, […]

The influence of two species of arbuscular mycorrhizal fungi (AMF) on the ATPase and pyrophosphatase activities of corn root microsomes was investigated at 20, 30, 40, and 60 days after planting. The microsomes were isolated by cell fractionation from corn roots colonized with Glomus clarum or Gigaspora margarita. Both fungi led to a significant increase in the ATPase and pyrophosphatase activities though the highest activities were observed in roots colonized with G. clarum. Kinetics analysis suggested that mycorrhizal colonization promoted a […]

In order to evaluate the amount of immobilized N and the amount of N-fertilizer recovered by corn plants at the stages:5-6 leaves, 11-12 leaves, flowering, and physiologic maturation, ammonium sulfate (AS) and urea (U), labeled with 15N, were applied to maize in a no-till system 43 days before planting and 31 days after planting at a single rate of 80 kg ha-1 of N incorporated at 5-7 cm depth and in a spacing of 0.8 m. Corn was sown after black oat (Avena strigosa Schieb.). The treatments were […]

Farm planning requires an assessment of the soil class. Research suggest that the Diagnosis and Recommendation Integrated System (DRIS) has the capacity to evaluate the nutritional status of coffee plantations, regardless of environmental conditions. Additionally, the use of DRIS could reduce the costs for farm planning. This study evaluated the relationship between the soil class and nutritional status of coffee plants (Coffea canephora Pierre) using the Critical Level (CL) and DRIS methods, based on two multivariate statistical methods (discriminant and […]

Alterations in soil chemical properties after liming depend on the frequency of soil sampling and rainfall. This study evaluated such alterations in a Typic Haplorthox (Rhodic Ferralsol) with a sandy-loam superficial layer. The experiment had a completely randomized block design, with four dolomitic lime rates (0, 2.4, 4.8, and 7.2 t ha-1) and three replicates. The experiment was carried out in Alto Parana in northwestern Parana state (southern Brazil). Lime was broadcast on the soil surface over Brachiaria decumbens grass residues in-between […]

Differences among plants in their ability to support nutritional stress periods may be caused by a differential vacuole capacity of ion storage and release and may also depend on the intensity of nutrient re-translocation under such conditions. In five soybean cultivars, submitted to eight days of P deprivation, the dry matter production and the contents of three phosphorus (P) forms – inorganic (Pi), organic (Po), and acid-soluble total (Pts) of different plant organs were determined. Pi release velocity (RSPi) was […]