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81.
The aim of this study was to assess genetic diversity and spatial distribution of 123 strains of the root‐rot pathogen Neonectria macrodidyma isolated from fine living roots of bare‐root nursery cultivated Pinus sylvestris. We found that ITS rDNA sequences were 100% identical for all strains. Arbitrary primed PCR fragment analysis showed the presence of two distinct N. macrodidyma types (Type 1 and Type 2), which included respectively 11 and 14 genotypes composed of 1–29 strains. Results of this study indicate that N. macrodidyma is commonly associated with fine living roots of pine seedlings, is largely disseminated by asexual means of local genotypes and has even distribution in the forest nursery soils. In living roots, N. macrodidyma is likely present as dormant propagules but under favourable conditions, it may develop rapidly and have a significant negative effect on plant health and productivity. 相似文献
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The uncatalyzed edge growth of carbon nanotubes was investigated by first-principles molecular dynamics simulations. At experimental temperatures the open end of single-walled nanotubes closed spontaneously into a graphitic dome, which may explain why these nanotubes do not grow in the absence of transition metal catalysts. On the other hand, chemical bonding between the edges of adjacent coaxial tubes ("lip-lip" interactions) trapped the end of a double-walled nanotube in a metastable energy minimum, thus preventing dome closure. These calculations show that this end geometry exhibits a high degree of chemical activity and easily accommodates incoming carbon fragments, supporting a model of growth by chemisorption from the vapor phase. 相似文献
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Vita Ratri Cahyani Jun Murase Eiji Ishibashi Susumu Asakawa Makoto Kimura 《Biology and Fertility of Soils》2009,45(4):337-346
We isolated manganous ion (Mn2+) oxidizing bacteria and fungi from Mn nodules collected from two Japanese rice fields. The phylogenetic position of the Mn-oxidizing
bacteria and fungi was determined based on their 16S rDNA and 18S rDNA sequences, respectively. Among 39 bacterial and 25
fungal isolates, Burkholderia and Acremonium strains were the most common and dominant Mn2+-oxidizing bacteria and fungi, respectively. Majority of the Mn-oxidizing bacteria and fungi isolated from the Mn nodules
belonged to the genera that had been isolated earlier from various environments. Manganese oxide depositions on Mn2+-containing agar media by these microorganisms proceeded after their colony developments, indicating that the energy produced
from Mn2+ oxidation is poorly used for microbial growth. 相似文献
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Audrius Menkis Aistė Povilaitienė Adas Marčiulynas Jūratė Lynikienė Artūras Gedminas Diana Marčiulynienė 《Scandinavian Journal of Forest Research》2019,34(1):26-32
The horse chestnut leaf-miner (Cameraria ohridella Deschka & Dimi?, Lepidoptera, Gracillariidae) is an invasive pest causing extensive damage to leaves of the horse-chestnut (Aesculus hippocastanum L.) in Europe. In Lithuania, C. ohridella invaded in 2002 causing wilting, browning and premature fall of A. hippocastanum leaves. The aim was to get a better understanding of possible linkages between foliar fungal communities and leaf-miner damage in A. hippocastanum. Leaves of A. hippocastanum, differentially damaged by C. ohridella, were collected in 10 sites in Lithuania. The fungal communities were described through DNA isolation and amplification using an ITS rRNA marker and Ion Torrent-sequencing. Clustering of 214,897 high-quality sequences resulted in 1017 non-singleton fungal taxa, among which Aureobasidium pullulans (28.2% of all fungal sequences), Endoconidioma populi (27.7%), Phoma fungicola (11.3%), Cladosporium ramotenellum (7.6%) and Cryptococcus sp. 2185_4 (5.0%) were most common. Correspondence analysis showed that fungal communities from heavily and slightly damaged leaves were largely intermingled, showing that in both types of samples fungal communities were similar. In conclusion, the study demonstrated that the phyllosphere of A. hippocastanum is inhabited by a high diversity of fungal species, the majority of which constitute generalist endophytes, epiphytes and saprotrophic fungi. The occurrence of common phyllosphere fungi was unrelated to the degree of damage by C. ohridella. 相似文献
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Phytate and mineral elements concentration in a collection of Italian durum wheat cultivars 总被引：1，自引：0，他引：1
D.B.M. Ficco C. RiefoloG. Nicastro V. De SimoneA.M. Di Gesù R. BeleggiaC. Platani L. CattivelliP. De Vita 《Field Crops Research》2009
Mineral deficiencies are prevalent in human populations and the improvement of the mineral content in cereal products represents a possible strategy to increase the human mineral intake. Nevertheless, most of the inorganic phosphorus (Pi) present in mature cereal seeds (40–80%) is stored as phytate, an anti-nutritional factor that forms complexes with minerals such as Ca, Mg, Zn and Fe reducing their bioavailability. The present study was undertaken: (i) to determine the variation in phytate and mineral concentrations in the whole grains of 84 Italian durum wheat (Triticum durum Desf.) cultivars representative of old and modern germplasm; (ii) to estimate the magnitude of genotype × environment interaction effects; and (iii) to examine the interrelationships among mineral concentrations in durum wheat with the final aim to identify superior durum wheat cultivars that possess low phytate content and high concentration of mineral elements in their whole-wheat flour. The cultivars were grown in field trials during 2004–2005 at Foggia, Italy and during 2005–2006 at Foggia and Fiorenzuola d’Arda—Southern and Northern Italy. The phytate content was estimated indirectly by using a microtitre plate assay evaluating the Pi absorbance at 820 nm, while the Cu, Fe, Mn, Ca, K, Mg, Na and Zn mineral contents were determined by ICP/OES. The contents of Zn and Fe across years and locations ranged from 28.5 to 46.3 mg/kg for Zn with an average of 37.4 mg/kg and from 33.6 to 65.6 mg/kg for Fe with an average of 49.6 mg/kg. Pi grain content was between 0.46 and 0.76 mg/g showing a positive correlation with all minerals except Cu and Zn. Although breeding activity for Fe and Zn would be difficult because G × E interaction is prevalent, multi-location evaluation of germplasm collection help to identify superior genotypes to achieve this objective. The results here reported open the possibility of designing a specific breeding program for improving the nutritional value of durum wheat through the identification of parental lines with low-Pi and high minerals concentration in whole grains. 相似文献
86.
P. De Vita A.M. Mastrangelo L. Matteu E. Mazzucotelli N. Virzì M. Palumbo M. Lo Storto F. Rizza L. Cattivelli 《Field Crops Research》2010
In durum wheat (Triticum durum Desf.) the improvement of yield stability represents an important component for agricultural progress worldwide. This work reports on the evaluation of the yield performance of 65 durum wheat genotypes (landraces, old and new cultivars with different years of release and advanced breeding lines), in a range of Italian environments to assess the changes in adaptation and yield stability achieved over the last century as results of the genetic improvement. The Additive Main effect and Multiplicative Interaction (AMMI) analysis was used to capture a large portion of the Genotype × Environment interaction (GE) sum of squares and to separate main and interaction effects. The breeding strategies adopted during the last decades have contributed to reduce the interaction of genotypes with environments selecting genotypes with better stability across a wide range of locations and years and modern genotypes outperformed the old ones in all test environments with a strong adaptability to improved fertility. The old cultivars were characterized by a minimal responsiveness to improved environmental conditions, showing an almost stable nominal yield in agreement with the concept of “biological” or “static” stability. In contrast, the modern cultivars were highly responsive to fertility improvements and showed a pronounced adaptation to high-input environments. Notably, within the group of modern cultivars two of them, Tiziana and Giusto, showed a high-yield stability in biological terms and a high nominal yield across the tested environments. Giusto and Tiziana were the best cultivars in terms of both nominal yield and minimal GE interaction, indicating that selecting for improved yield potential may increase yield in a wide range of environments. 相似文献
87.
Algirdas Augustaitis Ingrida Augustaitienė Almantas Kliučius Gintaras Pivoras Dalia Šopauskienė Raselė Girgždienė 《European Journal of Forest Research》2010,129(3):431-441
The multiple-stressor effects of air pollution, nutrient and water availability are the key issues of present forest ecosystem
research. However, too little is known about the seasonal effect of pollutants on tree crown defoliation and their interaction
with changes in climate. Therefore, data on seasonal variation in air pollution, including surface ozone, deposition of acidifying
compounds and meteorological conditions, were tested against pine defoliation to identify the periods when the effect of the
considered contaminants is most pronounced. The findings of the study revealed that a higher level of air concentrations of
acidifying pollutants and their deposition was observed during the dormant period, with the exception of only ΣNH4+ air concentrations and their monthly deposition. An increase in precipitation over the vegetation period and mean monthly
temperature from September to December, as well as a decrease in temperature and precipitation over the remaining months of
the dormant period represented the climate change condition over the 14-year period in the observed region. Detected changes
in the considered parameters during the dormant period were found to be most significant to changes in pine crown defoliation.
Therefore, we concluded that climate changes, if they occur by the detected scenarios, should mitigate the negative effect
of air pollutants and acid deposition on pine crown condition. 相似文献
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Tuna farming is based on fishing bluefin tuna in their natural habit of the western Mediterranean and fattening them in floating cages. Although this type of aquaculture is expanding rapidly in the Mediterranean Sea, very little information is available for an environmental impact assessment and environmental monitoring of tuna ranching. Spatial and temporal scales of impact need to be established before the norms and regulations affecting this new branch of aquaculture can be properly implemented. The biotic indices measured pointed to detectable impact only under the cages, although multivariate techniques defined an environmental gradient of stressed macrofaunal assemblages. The benthic surveys carried out indicated that high impact was restricted to a radius of roughly 5 m from the cages with a transitional radius at 35 m. This zone was characterized by high densities of opportunistic species. There was a further zone of moderately stressed benthic environment extending to about 180–220 m from the cages. This moderately stressed zone exhibited slight changes in community structure, because the densities of some species were stimulated. At distances greater than 220 m from the tuna farm, the system apparently returned to normal conditions. The fallow period produced partial remediation of the area affected, except in the sediment underneath the cages where even a 6‐month fallow period was not sufficient for the community to totally recover. 相似文献