1,721,033 research outputs found
I progressi dell'analisi fisico-chimica per l'accertamento dell'origine e genuinità dei vini
No full textInterregional and interannual variability of ethanol site-specific deuterium content in Italian wines
No full textSNIF-NMR 2H analysis of alcohols of Italian genuine wines: study of interregional and interannual variability
No full textSoil organic matter mobilization by root exudates of three maize hybrids
No full textIn order to study the macromolecular behaviour of humic substances, we treated humic material (from the
Ah horizon of an Eutric Cambisol) either with exudates From 10 day-old seedlings obtained in axenic conditions
from three maize cultivars (Zea mays L. ; cv. Paolo, cv. Polaris and cv. Sandek) or with the organic acids (succinic
and fumaric) present in the exudates and followed the change in molecular size distribution. Succinic acid , Polaris
and Sandek exudates shifted the humic absorbance from high to low molecular weight in size exclusion
chromatogram,s while Paolo exudates were not able to produce the same shift and gave an absorbance profile like
that of humic substance alone. Our results are evidence of the micellar behaviour of humic substances in solution and
of the importance of hydrophobic bonds in holding humic molecular together.
Exudates were also used to separate soil organic fractions from the same soil. Soil organic extracts were
characterized by low pressure gel permeation chromatography, hormone-like activities, and ‘H-NMR. The data,
compared with water extract and KOH extract, indicate that maize exudates, fumaric and succinic acids mobilize soil
organic fractions in small quantities, but these extracts are endowed with auxin- and/or gibberellin-like activity.
Water extract and maize exudates exhibit no hormone-like activity, while KOH extract shows a negligible one.
Moreover, only Polaris and Sandek exudates and succinic acid are able to disaggregate an organic fraction with low
apparent molecular size (<13KDs) from the bulk of the soil. The ‘H-NMR data indicate that water and succinic
extracts are largely composed of carbohydrate and aliphatic constituents, Sandek exudate and fitmaric acid can
liberate aromatic components, Polaris exudate releases carbohydrates from soil, while Paolo slightly influences the
aliphatic constituents.
The role of organic acids released by maize seedlings in mobilising soil organic fractions is presented
Isotopic ratio mass spectrometry: an evaluation of some parameters of in vitro fermentation
No full textChemical and biochemical properties of humic substances isolated from forest soils and plant growth
No full textTo investigate the relationships among litter composition and 13C–nuclear magnetic resonance spectra (13C–NMR), we studied d13C values and biochemical activities of the humic constituents extracted from the Ah horizons of two undisturbed forest soils, located in a unique climatic area under different vegetative covers, Pinus mugo T. Pinus sylvestris L. The two litters differed greatly in composition, while the 13C–NMR spectra of the humic substances extracted from the two Ah horizons were similar. The 13C–NMR spectra of the low
molecular humic size (LMS) 1–2 revealed high aromatic and carbox- ylic contents and low aliphatic and carbohydratic ones. The total humic extracts (TQ) 1–2 and the high molecular humic size (HMS) 1– 2 exhibited an opposite trend. The d13C values of the humic fractions ranged from 224.96 to 225.84‰, indicating an advanced stage of humification. The biochemical activities of the humic fractions were studied by evaluating the invertase, peroxidase, and esterase activities in Pinus mugo and Pinus sylvestris seedling roots grown in the presence of their humic matter. These forest species were differently affected by their humic substances. In particular, the Pinus sylvestris humic matter, endowed with a higher indoleacetic acid (IAA) content, positively influenced all the enzymes tested in Pinus sylvestris seedlings, while the Pinus mugo humic matter only increased the peroxidase activity in its seedlings. The plant species differ in their capacity to respond to biological humus activity, which is reflected in their natural distribution
Relationships between deuterium dilution space and estimated energy balance in lactating goats
No full textIn this study the effects of pregnancy, diet and stage of lactation on energy balance of dairy goats were compared. Energy balance was predicted both with the deuterium oxide technique and with measurement of energy consumption and the requirement for milk production, pregnancy and maintenance. The study was a 2 X 2 Latin square design with two different diets (15.6% and 25.9% ADF in DM) fed in two periods to two groups of three lactating does housed in digestion crates. Each period lasted 4 weeks and was preceded by an adaptation period of 2 weeks. A complete energy balance was calculated for each goat in each period by measuring daily feed intake, milk yield, faeces and urine. Energy retention was calculated as difference between the total milk net energy intake and the milk net energy used for maintenance, pregnancy and milk production. Changes in body composition between the beginning and the end of each period were estimated by means of the deuterium technique, and energy retention was calculated using 39.6 MJ and 23.6 MJ kg(-1) caloric equivalent for fat and protein gains, respectively. Data were analysed according to a split-plot model in which pregnancy, diet and period were fixed effects and animal nested in pregnancy was a random effect. The two approaches provided similar estimates of the average effects of pregnancy, diet and period on energy retention. Higher variability was observed with the isotopic procedure. The precision and accuracy of the isotopic procedure can be improved by increasing the number of experimental animals and the length of the trial
BIOLOGICAL ACTIVITY OF HUMIC SUBSTANCES EXTRACTED FROM SOILS UNDER DIFFERENT VEGETATION COVER
No full textComparisons were made between the chemical compositions of humic substances extracted
from three soils covered by different vegetation and their biological activities assayed using
15 and 30 day old seedlings of Pinus sylvestris and Picea abies. The growth, -amylase and
invertase activity were affected by humic fractions and by gibberellic acid (GA), indicating
that humic matter had a gibberellin-like activity.
The isoenzymatic polymorphism in the electrophoretic patterns of esterase was influenced in a
similar way by all humic fractions and by indoleacetic acid (IAA), which also suggested that
the humic fractions exhibited an auxin-like activity. The humic fractions extracted from the
grassland, exhibiting higher amounts of phenolic and a considerable amount of carboxyl
carbon, showed the best metabolic effect. The forest humic fractions, characterized by lower
2
phenolic carbon content, appeared less effective in influencing plant metabolism, whereas the
grassland-forest humic substances proved to be even more less effective.
The auxin- and the gibberellin-like activities were related to a high content of phenolic and
carboxylic groups. These results presented evidence that the biological activity of the humic
substances was attributed to their chemical structure and to their functional groups, which
could interact with hormone-binding proteins in the membrane systems, evoking a hormonelike
response
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