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Green peach aphid populations were monitored by using water trap pans and by taking leaf samples in 38 southwestern Idaho potato fields from 1972 to 1975. Numbers of winged aphids in trap pans were correlated with populations of aphids developing in adjacent fields but were not predictive of future population trends. Trap pan data are, however, useful in alerting growers to the possibility of damaging field populations which exist in a field at the time of sampling. 相似文献
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Guy Carvajal William Thilly 《Plant foods for human nutrition (Dordrecht, Netherlands)》1988,38(2):105-114
Cultured AHH1 human lymphoblast cells were exposed to an extract ofMintostachys mollis, which is used as a medicinal plant and preservative in Peru, to detect its mutagenic activity. A three-day exposure to concentrations of 1, 10, 30 and 50 µg/ml resulted in induced mutant fraction of 1.02, 1.79, 2.21 and 3.80 mutations per million cells per day, expressed as 6-Thioguanine resistance. A concentration of 10µg/ml induced 11.9 times the spontaneous mutant fraction of AHH1 cells. The doubling dose determined to be 838 ng/ml. A concentration of 30 µg/ml of this compound resembled the induced rate of 1 µM benzo () pryene. 相似文献
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ABSTRACT Chitosan (CHN), a deacetylated derivative of chitin, was shown to be efficient in promoting plant defense reactions. CHN oligomers of different molecular weight (MW) and degree of acetylation (DA) triggered an accumulation of phytoalexins, trans- and cis-resveratrol and their derivatives epsilon-viniferin and piceid, in grapevine leaves. Highest phytoalexin production was achieved within 48 h of incubation with CHN at 200 mug/ml with an MW of 1,500 and a DA of 20% (CHN1.5/20), while oligomers with greater MW were less efficient, indicating that a specific MW threshold could be required for phytoalexin response. Treatment of grapevine leaves by highly active CHN1.5/20 also led to marked induction of chitinase and beta-1,3-glucanase activities. CHN1.5/20 applied together with copper sulfate (CuSO(4)) strongly induced phytoalexin accumulation. CuSO(4) alone, especially at low concentrations also elicited a substantial production of phytoalexins in grapevine leaves. Evidence is also provided that CHN1.5/20 significantly reduced the infection of grapevine leaves by Botrytis cinerea and Plasmopara viticola, and in combination with CuSO(4) conferred protection against both pathogens. 相似文献
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Landscape Ecology - Studying biodiversity in light of increased fragmentation in agroecosystems requires the understanding of scale-dependent and multi-scale determinants of various community... 相似文献
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