Short-term effects of ammonium nitrogen in upland pasture soil affected or not affected by cattle

The short-term effects of excessive NH₄⁺-N on selected characteristics of soil unaffected (low annual N inputs) and affected (high annual N inputs) by cattle were investigated under laboratory conditions. The major hypothesis tested was that above a theoretical upper limit of NH₄⁺ concentration, an excess of NH₄⁺-N does not further increase NO₃⁻ formation rate in the soil, but only supports accumulation of NO₂⁻-N and gaseous losses of N as N₂O. Soils were amended with 10 to 500 μg NH₄⁺-N g⁻¹ soil. In both soils, addition of NH₄⁺-N increased production of NO₃⁻-N until some limit. This limit was higher in cattle-affected soil than in unaffected soil. Production of N₂O increased in the whole range of amendments in both soils. At the highest level of NH₄⁺-N addition, NO₂⁻-N accumulated in cattle-affected soil while NO₃⁻-N production decreased in cattle-unaffected soil. Despite being statistically significant, observed effects of high NH₄⁺-N addition were relatively weak. Uptake of mineral N, stimulated by glucose amendment, decreased the mineral N content in both soils, but it also greatly increased production of N₂O.     

Amylolysis of wheat starches. II. Degradation patterns of native starch granules with varying functional properties

Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to investigate degradation patterns of native starch granules from wheat (Triticum aestivum L.) by different starch-degrading enzymes. The starches examined were from a waxy wheat and four varieties with slightly elevated amylose content, but with different functional properties. Differences in the digestion patterns after partial α-amylolysis of starch granules were noted between the starches. The waxy starch seemed to be degraded by endocorrosion, whereas the amylose-rich starches followed a slower mode of hydrolysis starting from the granular surface. X-ray diffractograms of the amylose-rich starches were not significantly altered by 2 h of α-amylolysis, whereas partial hydrolysis of the waxy starch decreased scattering intensity at higher 2θ angles, consistent with a different mode of attack by α-amylase in the initial digestion stages of granules of waxy and amylose-rich starches. We propose these differences are due to the combined effects of the change in packing density and partial preference for hydrolysis of amorphous material. The native starch granules were also attacked by beta-amylase, isoamylase and amyloglucosidase, which indicates that α-amylase is not the only starch-degrading enzyme that is able to initiate starch hydrolysis of native granules.     

Effect of β‐Glucan on Technological,Sensory, and Structural Properties of Durum Wheat Pasta

β‐Glucan is known to have valuable properties for preventative health and is finding widespread use in foods. This study investigated the benefit of adding a commercial source of β‐glucan, Barley Balance (BB) flour, as a functional ingredient in spaghetti. Durum wheat semolina was substituted with BB at levels of 7.5, 15, and 20%, from which spaghetti was prepared on a laboratory scale. The substitution of BB increased the β‐glucan content of semolina from 0.3 to 6% in uncooked and 8% in cooked pasta. Antioxidant activity (measured by 2,2‐diphenyl‐1‐picrylhydrazyl) increased with BB and did not decline significantly on processing and cooking. Compared with the control, 7.5% BB had no or minimal effect on pasta cooking loss, stickiness, water absorption, aroma, and sensory texture. However, at higher doses, pasta became less yellow and more brown, firmer, of inferior aroma, more rubbery, and chewy, but less floury to the mouth. The extent of starch digestion decreased with increasing quantities of BB, suggesting that BB may lower glycemic index, with microscopy data suggesting that this decrease was mediated through the development of a more intensive fiber or fiber/protein matrix retarding enzymatic access to starch granules.     

Physiological response of irrigated and non-irrigated Norway spruce trees as a consequence of drought in field conditions

Physiological reactions of 25-year-old Norway spruce (Picea abies (L.) Karst.) trees to drought were examined during 2009 vegetation period. During the second half of summer, the decrease in soil water content was observed and irrigation was applied to a group of spruce trees, while the second group was treated under natural soil drought. The response to water deficit was recorded at the level of leaf water potential (Ψ_L). However, it appears that Ψ_L plays minor role in early stomata regulation of Norway spruce as CO₂ assimilation rate (P _N) and stomatal conductance (g _S) were reduced already before water potential decrease. Leaf water potential decreased significantly only in case when soil water content was low in the long run and when transpiration losses were simultaneously relatively high. Almost complete stomatal closure even of the irrigated trees was caused by the increase in the vapour pressure deficit of the air (D) above the value of approximately 1.5?kPa. Low values of D were accompanied by partial stomata opening of drought-treated trees. In non-irrigated spruce trees, the values of P _N decreased by 35–55% in comparison with irrigated trees. No drought-induced significant changes were found either in chlorophyll and carotenoid concentration (chl a?+?b, car) or in maximal photochemical efficiency of photosystem II (F _v/F _m). High rates of sap flow (F) did not always lead to stomatal closure during midday. It?appears that high transpiration rates do not control stomatal response to D.     

Über natürliche Infektionen und ihre Verbreitung in Mosquito-Larven (Anopheles spp. undCulex spp.) in Tanzania

Journal of Pest Science - Es wird über 1983–1985 in Tanzania gewonnene Erkenntnisse zur Art und Verbreitung von Pathogenen bei Stechmücken (Anopheles spp.,Culex spp.) berichtet. Die...     

Cell wall compositional and vascular traits of hybrid poplar wood in micropropagated plants and plants propagated from root cuttings

New Forests - The development of biotechnological approaches has increased the possibility to produce new genotypes of poplars with improved metabolic, growth, ecological or industrial properties....     

Detection of organophosphate and pyrethroid resistance alleles in Czech Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) populations by molecular methods

BACKGROUND: Pyrethroids and organophosphates are the most frequently used insecticides for Colorado potato beetle, Leptinotarsa decemlineata (Say), control in the Czech Republic. Based on molecular methods, organophosphate and pyrethroid resistance alleles have been detected in samples from three sites. The accuracy of restriction fragment length polymorphism (RFLP) and bidirectional polymerase chain reaction amplification of specific alleles (Bi‐PASA) for detection of resistance alleles is compared. RESULTS: Leptinotarsa decemlineata from three sites showed higher frequencies of resistance alleles to organophosphates than to pyrethroids. The rates of occurrence of individuals homozygous resistant (RR) to pyrethroids ranged from 20.0 to 22.9%, while the rates of occurrence of individuals RR to organophosphates ranged from 52.9 to 66.7%. The incidences of individuals with resistance alleles to both organophosphates and pyrethroids ranged from 8.6 to 13.6%. No relationship was found between incidence of the pyrethroid resistance allele and site, while incidence of the organophosphate resistance allele differed significantly according to site. CONCLUSION: Both RFLP and Bi‐PASA were suitable for detecting resistance alleles to pyrethroids, and in most cases also for detecting resistance alleles to organophosphates. In contrast to Bi‐PASA, RFLP was also suitable for samples with lower DNA quality when testing for the resistance allele to pyrethroids. On the other hand, RFLP was not as accurate as Bi‐PASA in detection of the organophosphate resistance allele. Copyright © 2010 Society of Chemical Industry     

Further spread of the gypsy moth fungal pathogen,Entomophaga maimaiga,to the west and north in Central Europe

Journal of Plant Diseases and Protection - The gypsy moth, Lymantria dispar, is one of the most important pests of deciduous trees in Europe, occurring in all environmental zones of Europe except...     

Dendroctonus micans populations on Picea pungens in the center of a non-outbreak region contain few pathogens,parasites or predators: A new threat for urban forests?

In reviewing the occurrence of the bark beetle Dendroctonus micans in the Czech Republic over the past 100 years, we found that D. micans has been detected at 80 localities with elevations ranging from 158 to 1350 m a.s.l. During 2011–2012, we recorded three local outbreaks on Picea pungens, two of which involved isolated trees in urban areas between houses (always on sites <1 ha). From these locally abundant populations, 125 adults, 5 pupae, and 73 larvae of D. micans were obtained and dissected. Among these dissected specimens, nematodes in the hemolymph were detected in only 5 adults and 11 larvae. No other parasites or pathogens were found in the D. micans specimens. Low numbers of the beetle Rhizophagus grandis, which is a specific predator of D. micans, were detected, and none contained parasites or pathogens. Locally D. micans could constitute a new limited threat to urban trees, including P. pungens, in the Czech Republic and Central Europe. Special attention should be given to solitary P. pungens trees; if D. micans is detected on these trees, defensive measures must be taken to protect uninfested trees in the vicinity.     

Finite element analyses in wood research: a bibliography

This paper gives a bibliographical review of the finite element methods (FEMs) applied in the analysis of wood. The added bibliography at the end of this article contains 300 references to papers and conference proceedings on the subject that were published between 1995 and 2004. The following topics are included: Wood as a construction material—material and mechanical properties; wood joining and fastening; fracture mechanics problems; drying process, thermal properties; other topics. Wood products and structures—lumber; glulam, panels, wood composites; trusses and frames; floors, roofs; bridges; other products/structures.