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Esperanza, Argentina

Acosta J.M.,IAL | Panigo E.S.,IAL | Dellaferrera I.,IAL | Perreta M.G.,IAL
Weed Research

Summary: Controlled growth chamber experiments were conducted to determine factors affecting seed germination and emergence of the troublesome weed Gomphrena perennis. The objective of this research was to examine the effects of temperature, light, moist chilling, osmotic potential, dry storage and depth of seed burial on G.perennis germination and emergence. The optimum temperature for germination was around 15-20°C. Seeds showed germination rates above 90% under 20/10 and 25/15°C temperature regimes. The minimum exposure to light needed to stimulate germination was 1min. However, the light requirement was reduced after a long storage period. Furthermore, germination was high (>90%) in all moist-chilling treatments tested. Germination was highly sensitive to increasing osmotic stress. The highest germination percentage (94%) was achieved at 0MPa, and decreasing osmotic potential from 0 to -0.3MPa reduced germination to 11%. The highest seedling emergence occurred for seeds placed from 0 to 1cm deep, and no seedlings emerged from a 5-cm burial depth. Gomphrena perennis has a suitable environment in a no-till soybean field, where seeds remaining on the surface have the required temperature, light and depth needed for germination. © 2012 European Weed Research Society. Source

Abakerli R.B.,University of Campinas | Sparrapan R.,University of Campinas | Sawaya A.C.H.F.,University of Campinas | Eberlin M.N.,University of Campinas | And 8 more authors.
Food Chemistry

Golden, Sunrise Solo and Tainung cultivars of papaya were found to release CS2 when submitted to experimental conditions of dithiocarbamate residue analysis. Three common analytical methods were used to quantitate CS2; one spectrophotometric method and two chromatographic methods. All three methods gave positive CS2 results for all three papaya varieties. Other endogenous compounds present in isooctane extracts of papaya fractions detected via gas chromatography (GC/ITD) using electron ionization (EI) were: carbonyl sulfide, dimethyl sulfide, carbon disulfide, 2-methylthiophene, 3-methylthiophene, 2-ethylthiophene, 3-ethylthiophene, benzylisothiocyanate, benzylthiocyanate and benzonitrile. Control samples were obtained from papaya plantations cultivated in experimental areas, in which no treatment with fungicides of the dithiocarbamate group was applied. Endogenous CS2 levels were compared with true dithiocarbamate residues measured in papaya samples from the field trials following applications of the mancozeb fungicide. Three days after application, true dithiocarbamate residues, measured by the procedure with isooctane partitioning and GC-ITD, were at the average level of 2 mg kg-1. © 2015 Elsevier Ltd. Source

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