Time filter

Source Type

Florianópolis, Brazil

Zaro G.C.,State University Londrina | Da Silva Ricce W.,Epagri Ciram | Vicentini M.E.,State University Londrina
Revista Brasileira de Fruticultura | Year: 2014

Avocado cultivars have a great diversity of tolerance to low temperatures due to their regions of origin. The Mexican breeds are more tolerant, the West Indian breeds are more sensitive and the Guatemalan breeds have intermediate behavior. In this study, the zoning of climate risks in the state of Parana was based on the severity of frost, through the analysis of historical series of minimum temperatures in a Geographic Information System. We identified four distinct areas of risk, namely, a zone with very strong and frequent frosts where cultivation is not recommended, a zone where frosts are strong and only the cultivar Fuerte is recommended, a zone with moderate frosts and only Primavera and Margarida cultivars are not recommended, and a zone of low risk in the north and west of Paraná, where all cultivars are indicated. The diversity of climates in Paraná and thermal requirements of the cultivars allow the harvest during most of the year through a combination of different cultivars and growing regions. © 2014, Sociedade Brasileira de Fruticultura. All rights reserved.

Bitencourt D.P.,Fundacentro | Manoel G.,National Institute for Space Research | Acevedo O.C.,Federal University of Santa Maria | Fuentes M.V.,University of Sao Paulo | And 3 more authors.
Meteorological Applications | Year: 2011

Intense wind events at the southern Brazilian coast cause severe socio-economic losses. Generally, such events have been associated with extratropical cyclones over the Southwest Atlantic Ocean. The purpose of this study is to identify favoured locations and the processes through which the winds are associated with the extratropical cyclones. Using a statistical analysis, the wind speed observed at nine meteorological stations was compared with cyclone depth and offshore distance. Both cyclone depth and location were obtained through an objective procedure of identifying and tracking. Generally, the winds are well associated with the extratropical cyclones only south of 28°S. Altitude also plays an important role in this relationship. Furthermore, the cyclones influence the observed wind field up to 1200 km inland at higher latitude locations. For stations near 28°S, cyclones further from the coast have an influence, but with smaller statistical significance. © 2010 Royal Meteorological Society.

Debaeke P.,French National Institute for Agricultural Research | Debaeke P.,National Polytechnic Institute of Toulouse | van Oosterom E.J.,University of Queensland | Justes E.,French National Institute for Agricultural Research | And 5 more authors.
Field Crops Research | Year: 2012

For annual and perennial crops, mathematical models have been developed to describe tissue nitrogen (N) dilution during crop growth and to estimate the plant N status applying the N nutrition index (NNI), the ratio between the actual tissue N concentration ([N]) and the tissue N concentration needed to obtain the maximum instantaneous crop growth rate (critical tissue N concentration, [N] c). The relationship between shoot [N] c and shoot dry matter (DM, tha -1) can be described by an allometric power equation: [N] c=aDM -b, where a and b are crop-specific parameters. Critical N dilution curves (CNDC) have been determined for several C 3 crops but not specifically for sunflower (Helianthus annuus L.). The objectives of this work were to (i) determine and validate the N dilution curves for critical, minimum, and maximum [N] for sunflower from the juvenile stages to the end of flowering, (ii) compare the critical curve with published CNDCs for other C 3 crops, and (iii) estimate the range of variation of NNI for different levels of N fertilization and irrigation. A wide range of field experiments from Argentina, Australia, France, Italy, and Spain was used to establish the dilution curve for sunflower and to independently validate it. The fitted CNDC [N] c=4.53DM -0.42 yielded lower values for [N] c than references used until now for diagnosis and decision making in sunflower. The value of parameter a was generally similar to that of other C 3 species, but the value for parameter b differed. This was possibly associated with species differences in dry mass partitioning, and justified the development of a sunflower-specific CNDC. A preliminary reference curve for maximum [N] suggested an evolution from the juvenile stages to the end of flowering similar to that of [N] c. Minimum [N], in contrast, appeared to be more constant over time. Relationships between relative grain yield and NNI across a range of locations indicated that in general, maximum grain yield was reached around NNI=0.8, although at one location this was around NNI=1.0. The CNDC can provide useful applications for crop modeling, N status diagnosis, and N fertilization decision. © 2012 Elsevier B.V.

Araujo I.S.,Epagri Ciram | Oliveira J.L.R.,Epagri Ciram | Alves R.G.C.M.,Federal University of Para | Filho P.B.,Campus Universitario | da Costa R.H.R.,Campus Universitario
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2012

The swine manure contributes significantly to the degradation of natural resources and to decrease the quality of life in the southern state of Santa Catarina, Brazil. The excess of manure produced by the large number of pigs per unit area hinders the solution of the problem. This study aimed to evaluate the behavior of a system developed to treat swine manure, in series and in real scale, composed of anaerobic units, aerobic units and post-treatment. The parameters analyzed were: BOD, COD, TP, PO4-P, NH3-N, TKN, pH, chlorophyll a, algal biomass, total coliforms and fecal coliforms (Escherichia coli). The system showed that, after one year of operation, the removal efficiencies were satisfactory for organic matter and nutrients, reaching values of 97% for BOD, 95% for COD, 88% for N-NH3 and 74% for PT/P-PO4, even with variations in flow and organic load applied. However the removal of fecal coliforms in the aerobic units was low, decreasing only 0.86 log units in the aerated facultative pond and 0.80 log units in the maturation pond.

Massignam A.M.,Epagri Ciram | Massignam A.M.,University of Queensland | Chapman S.C.,CSIRO | Hammer G.L.,University of Queensland | Fukai S.,University of Queensland
Crop and Pasture Science | Year: 2011

Nitrogen (N) limitation reduces canopy carbon assimilation by directly reducing leaf photosynthesis, and by developmentally reducing the rate of new leaf area development and accelerating leaf senescence. Effective use of N for biomass production under N limitation may be considered to be a result of a trade-off between the use of N to maintain high levels of specific leaf nitrogen (SLN the amount of N per unit leaf area) for high photosynthetic rate versus using N to maintain leaf area development (leaf area index LAI). The objective here is to compare the effects of N supply on the dynamics of LAI and SLN for two crops, maize (Zea mays L.) and sunflower (Helianthus annuus L.) that contrast in the structure and development of their canopy. Three irrigated experiments imposed different levels of N and plant density. While LAI in both maize and sunflower was reduced under N limitation, leaf area development was more responsive to N supply in sunflower than maize. Observations near anthesis showed that sunflower tended to maintain SLN and adjust leaf area under reduced N supply, whereas maize tended to maintain leaf area and adjust SLN first, and, when this was not sufficient, SLN was also reduced. The two species responded differently to variation in N supply, and the implication of these different strategies for crop adaptation and management is discussed. © 2011 CSIRO.

Discover hidden collaborations