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Andrei Canarache Iuliu Colibas Maria Colibas Ion Horobeanu Viorica Patru Horia Simota Theodor Trandafirescu 《Soil & Tillage Research》1984,4(2):199-213
Results of field experiments with soil compaction induced by wheel traffic applied uniformly to cover the entire surface of the experimental plots are reported. Compaction was done immediately before sowing, and each year, in each location, the same treatments were repeated on the same plots. The number of tractor passes varied between 0 and 30. The experiments were conducted during the 1978–1981 period in four locations with different soil and climatic conditions.Changes in soil physical properties, as well as in the yield of maize grain, were shown to be related to the number of tractor passes according to regression formulae of the type: Y = aXb. Most of the changes were recorded between 0 and 8–10 passes, while with more than 15–20 passes changes became negligible. The average maximum increase in bulk density was 20–25% as compared with the non-compacted control plot, and the average maximum decrease in yield was 46%. Moisture content in the compacted control plot, and the was 2–3% (w/w) lower than in the control plot, except for the soils with poor drainage where the lower part of the compacted topsoil showed an increase in moisture content. Air content in the compacted plots often dropped below 10, and occasionally to nearly 0% (v/v). For three of the four locations, grain yield of maize linearly decreased by 13 kg ha?1 (or 0.18% of the control plot yield) for each 1 kg m?3 increase in bulk density. 相似文献
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Budanov AV Sablina AA Feinstein E Koonin EV Chumakov PM 《Science (New York, N.Y.)》2004,304(5670):596-600
Acting as a signal, hydrogen peroxide circumvents antioxidant defense by overoxidizing peroxiredoxins (Prxs), the enzymes that metabolize peroxides. We show that sestrins, a family of proteins whose expression is modulated by p53, are required for regeneration of Prxs containing Cys-SO(2)H, thus reestablishing the antioxidant firewall. Sestrins contain a predicted redox-active domain homologous to AhpD, the enzyme catalyzing the reduction of a bacterial Prx, AhpC. Purified Hi95 (sestrin 2) protein supports adenosine triphosphate-dependent reduction of overoxidized PrxI in vitro, indicating that unlike AhpD, which is a disulfide reductase, sestrins are cysteine sulfinyl reductases. As modulators of peroxide signaling and antioxidant defense, sestrins constitute potential therapeutic targets. 相似文献
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Konstantin B. Gongalsky Fyodor A. Savin Andrei D. Pokarzhevskii Zhanna V. Filimonova 《European Journal of Soil Biology》2005,41(3-4):117-122
Soil macroinvertebrates were studied in a Mediterranean-type forest on brown-pebble forest soils in southern Russia. At the site, 144 intact soil cores (76 cm2 each) forming a grid of 24 × 6 units were taken in order to determine animal spatial distribution. Abundance of isopods was 166.3 ± 16.0 indiv. m–2 and they constituted about 12% of the total macrofaunal abundance. Biomass of isopods was 3.5 g m–2, or about 21% of the total biomass of macrofauna. Three woodlice genera (Armadillidium, Cylisticus, and Trachelipus) were found at the site. The two latter genera formed almost all (93%) of the isopod population. We found that spatial distribution of woodlice was heterogeneous: areas with 4–5 individuals per sample were neighboring those without animals. In order to study soil factors influencing isopod distribution in the brown-pebble forest soil, the size of a sample was artificially increased by combining adjacent sample units. Litter mass (r = 0.41) and loss on ignition (LOI) (r = –0.55) significantly influenced isopod distribution. Soil pH was near neutral (6.79), LOI was 8.39, and the water holding capacity was 70.9%. Pebbles comprised up to 84% of the sample's mass. Ca. 40 samples are recommended for estimation of isopod abundance in brown forest soil. 相似文献
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