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M. ÖZTüRK 《Plant biosystems》2016,150(6):1296-1305
Leaf area index (LAI) analysis of deciduous forest trees is usually restricted to seasonal monitoring involving the assessment of distinct leaf phenological stages within definite time intervals of the year. However, continuous LAI monitoring that includes entire leaf periods is necessary to define the ecophysiological characteristics of deciduous trees. Therefore, this study investigated the intra-annual cycle of the LAI for a Platanus orientalis L. stand in the Bart?n watershed of Turkey. A complete cycle involves three periods: foliation, stable, and defoliation. The foliation period comprises budburst, leaf emergence and flushing sessions, whereas the defoliation period consists of leaf senescence and leaf fall sessions. The stable period is in between these two periods when LAI values are at a climax around maximum. Eight points were determined in the field for the analysis of LAI by a hemispherical photography technique. Over a relatively frequent schedule, photographs were taken almost weekly during the foliation period. Both weekly and approximate monthly photographs were applied during the stable period. Finally, near-monthly photographs were taken for the defoliation period. The foliation period lasted for about 1.5 months from mid-April to May with the mean LAI reaching from 0.16 up to 2.38. Mean LAI was between 2.38 and 2.47 for a stable period over 2 months (June and July). For the defoliation period, mean LAI dropped from 2.42 down to 0.35 over 5 months from August to December. The total foliated period was more than 8 months, which is relatively long for a temperate forest. In addition, correlations between mean LAI and maximum, mean and minimum temperatures were highly significant (P < 0.01) with coefficients (r) of 0.79, 0.90 and 0.93, respectively. By describing the intra-annual LAI pattern, this study fills a gap in the literature on the phenology of Platanus orientalis L. 相似文献
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Invasion of globally threatened ecosystems dominated by arbuscular mycorrhizal plants, such as the alkaline prairies and serpentine
barrens of eastern North America, by species of ectomycorrhizal (ECM) pine (Pinus) seriously threatens the persistence, conservation, and ongoing restoration of these rare plant communities. Using Maryland
serpentine barrens and an Ohio alkaline prairie complex as model systems, we tested the hypothesis that the invasiveness of
Virginia pine (Pinus virginiana L.) into such communities is regulated by the spatial pattern of ECM fungal inoculum in the soil. ECM colonization of pine
seedlings can occur by (1) hyphae growing from the roots of mature ECM pines colonizing nearby seedlings (contagion model),
(2) pine seedlings being infected after germinating in open areas where spores are concentrated in feces of animals that have
consumed sporocarps (centers of infection model), and (3) colonization from spores that are wind-dispersed across the landscape
(background model). To test these models of dispersal of ECM fungal inoculum into these barrens, we used autocorrelation and
spatially explicit mapping techniques (semivariance analysis and kriging) to characterize the distribution and abundance of
ECM inoculum in soil. Our results strongly suggest that ECM fungi most often disperse into open barrens by contagion, thereby
facilitating rapid pine colonization in an advancing front from mature pine forests bordering the barrens. Spatial patterns
consistent with the centers of infection model were present but less common. Thus, current management techniques that rely
on cutting and fire to reverse pine invasion may be ineffective because they do not kill or disrupt hyphal mats attached to
mature roots of neighboring pines. Management alternatives are discussed. 相似文献
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ATLE MØRK DAVID WORSLEY 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1980,13(4):339-346
Girvanella , micritization phenomena and the dasycladacean alga Cyclocrinites are found in the middle Llandovery succession of the central Oslo Region. Both Girvanella and micritization phenomena occur in carbonate-dominated sequences where sedimentary structures and associated faunas suggest depositional environments above normal wave base. In contrast, Cyclocrinites occurs in shale-dominated sequences where other evidence suggests quiet, deep-water environments. We suggest that Cyclocrinites would not normally be preserved in situ in its life environment in relatively turbulent shallow waters. Preservation most commonly resulted from post mortem transport into low-energy muddy environments devoid of in situ algal activity. The resultant fossil is a flattened cast of this originally spherical alga. 相似文献
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T Török RK Mortimer P Romano G Suzzi M Polsinelli 《Journal of industrial microbiology & biotechnology》1996,17(3-4):303-313
Numerous studies have described the yeast biota of grapes, and grape must in order to understand better the succession of yeasts during fermentation of wine. The origin of the wine yeasts has been rather controversial. By using more elaborate isolation methods, classical genetic analysis and electrophoretic karyotyping of monosporic clones, with this study, credible proof now exists that the vineyard is the primary source for the wine yeasts and that strains found on the grapes can be followed through the fermentation process. 相似文献
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Sequence variation among 10 alleles of the alcohol dehydrogenase (Adh) gene
of the Hawaiian drosophilid D. mimica was analyzed with reference to the
evolutionary history of the Hawaiian subgroup as well as to levels and
patterns of polymorphism of the Adh gene in continental drosophilid
species. The Adh gene of D. mimica is less polymorphic than that of other
drosophilid species, and no replacement substitutions were found.
Statistical analyses of the Adh alleles suggested the action of balancing
selection and revealed significant linkage disequilibrium among three of
the variable sites. The effective population size was estimated to be only
slightly smaller than that of continental species and, surprisingly, on the
same order of magnitude as the actual size.
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Ömer ERTÜRK 《Entomological Research》2007,37(2):122-124
To identify a more effective and safe biological control agent against a common cabbage pest, Plutella xylostella (L.) (Lepidoptera: Plutellidae), the insecticidal effects of selected biological agents were evaluated. The highest insecticidal effects determined were 100, 73.5, 45.5, 47 and 55.3% using toxin HD‐1 (isolated from the Harry Dumagae strain of Bacillus thuringiensis), toxin BTS‐1 (isolated from the tenebrionis strain of B. thuringiensis), B. thuringiensis Berliner, B. thuringiensis israelensis and B. thuringiensis kurstaki, respectively. 相似文献
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Four species of Bacillus were isolated from soil in an effort to find safe, effective and alternative biological control agents against plant pests. These bacteria were identified as Bacillus pumilus, Bacillus sphaericus, Bacillus megaterium and Bacillus cereus on the basis of fatty acid methyl ester analysis and carbon utilization profiles by using Microbial Identification and Biolog Microplate Systems. Laboratory experiments carried out to determine the insecticidal activities of these isolates showed that B. pumilus caused 95.7 and 26.7% mortality and B. sphaericus caused 74.5 and 23.3% mortality of Leptinotarsa decemlineata larvae and adults, respectively. B. cereus and B. megaterium showed 51.1 and 29.7%, respectively, of L. decemlineata larvae. This study presents at least two Turkish isolates from the genus Bacillus showing high insecticidal activity against L. decemlineata. 相似文献