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151.
Summary. Surrogate leaves treated with methanolic leaf
surface extracts of Brassica napus L. (cv Express) plants
that received three different sulphur fertilisation treatments
showed even more marked differences by the oviposition
choice of Delia radicum L. than the potted plants. This
confirms that the oviposition preference of D. radicum is
mediated by chemical compounds on the leaf surface and
that the quality of host-plants in terms of their nutrition
status can be perceived by the female insect.The oviposition data were positively correlated with the
content of fractionated surface extracts containing either
CIF (cabbage identification factor; 1,2-dehydro-3-thia-
4,10,10b-triaza-cyclopenta[.a.]fluorine-1-carboxylic acid)
or glucosinolates. Electrophysiological recordings from the
tarsal chemoreceptor sensilla C5 and D3,4 showed that receptor
neurons react to glucosinolate- and CIF-fractions. We
found that the chemosensory activity of specific glucosinolate-
and CIF-receptor neurons corresponded with the
respective behavioural activity in the oviposition choice
assays. The responses of D. radicum to glucosinolates in
the electrophysiological recordings studies corresponded
to the observed oviposition preference on plants or artificial
leaves characterised with an higher amount of glucosinolates
on leave surfaces. The presented data suggested
that CIF and glucosinolates are involved in host-plant
preference of D. radicum and are perceived by tarsal
chemoreceptors. 相似文献
152.
Erich Hecker 《Die Naturwissenschaften》1967,54(11):282-284
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155.
Joris Mergaert Kurt Ruffieux Christophe Bourban Virginie Storms Wim Wagemans Erich Wintermantel Jean Swings 《Journal of Polymers and the Environment》2000,8(1):17-27
A simple and rapid in vitro test was designed for the assessment of the biodegradation of polyester-based plastics by selected biodegrading bacterial strains. Variovorax paradoxus LMG 16137 was used for the degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Acidovorax avenae subsp. avenae LMG 17238 fo the synthetic-based polyesters poly(-caprolactone) (PCL), poly(butylene succinate-co-butylene adipate), and a starch-PCL blend. Degradation by the bacteria was studied in liquid medium with the plastics (films, granules, and injection-molded test bars) as sole sources of carbon. Degradation was followed through gravimetry, growth of the culture, and tensile testing. The effects of incubation time, inoculum density, aeration, incubation temperature, and pH of the medium on the mass loss were investigated and conditions optimized. The test allowed to obtain reproducible results on the mass loss of plastic samples in less than 3 weeks and yielded excellent partially degraded samples for further analysis. 相似文献
156.
Bulk and low molecular weight (LMW) (<1 kDa) water-extractable carbon were collected from fresh and microbially degraded wheat straw (Triticum aestivum L.) and crimson clover (Trifolium incarnatum L.) residues to monitor early-stage humification over an 8-wk incubation. Copper complexation parameters were determined for both bulk and LMW water-extractable C for both plant materials in a separate 1-wk incubation. Humification progressed through increasing molar absorptivity (A285) and phenolic and total acidity (TA), and through an increase in average molecular size and degree of polymerization as determined by ultrafiltration and changes in fluorescence peak locations. Such dynamic transformations demonstrate that while humification is a bulk property, with C breakdown and stabilization occurring simultaneously and continuously in soil, its early stages can be effectively monitored for fresh plant residues. Significant changes consistently occurred during the first 7 d of the incubation and were more pronounced for LMW fractions than bulk extracts. For both residues, water-extractable C extracted initially and following a 7-d incubation desorbed and complexed 0.11 to 0.55 mmol resin-bound Cu g(-1) C. Low molecular weight water-extractable C generated the higher values within this range, and values increased consistently following incubation. Potential concerns regarding LMW soluble Cu complexes include percolation through soils or runoff into adjacent water bodies as well as effects on plant root development. 相似文献
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