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Ryan B. Mounce Susan A. O’Shaughnessy Brock C. Blaser Paul D. Colaizzi Steven R. Evett 《Irrigation Science》2016,34(3):231-244
In the High Plains, corn (Zea mays L.) is an important commodity for livestock feed. However, limited water resources and drought conditions continue to hinder corn production. Drought-tolerant (DT) corn hybrids could help maintain high yields under water-limited conditions, though consistent response of such hybrids is unverified. In this two-year study, the effects of three irrigation treatments were investigated for a DT and conventional maize hybrid, Pioneer AQUAMax P0876HR and Pioneer 33Y75, respectively. In 2013, the drier of the 2 years, irrigation amounts and crop water use (ETc) were greater for the conventional hybrid, but grain water use efficiency (WUE) and harvest index were significantly greater for the DT hybrid. In 2014, grain yields and WUE were not significantly different between hybrids. However, irrigation amounts, ETc and biomass yields were greater for the conventional hybrid. Results from both years indicate that the DT hybrid required less water to maximize grain yield as compared to the conventional hybrid. Producing relatively high yields with reduced amounts of water may provide a means for producers to continue corn production in a semiarid environment with declining water supplies. 相似文献
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F. Hagedorn S. Maurer P. Egli P. Blaser J. B. Bucher & R. Siegwolf 《European Journal of Soil Science》2001,52(4):619-628
Soil contains the major part of carbon in terrestrial ecosystems, but the response of this carbon to enriching the atmosphere in CO2 and to increased N deposition is not completely understood. We studied the effects of CO2 concentrations at 370 and 570 μmol CO2 mol?1 air and increased N deposition (7 against 0.7 g N m?2 year?1) on the dynamics of soil organic C in two types of forest soil in model ecosystems with spruce and beech established in large open‐top chambers containing an acidic loam and a calcareous sand. The added CO2 was depleted in 13C and thus the net input of new C into soil organic carbon and the mineralization of native C could be quantified. Soil type was the greatest determining factor in carbon dynamics. After 4 years, the net input of new C in the acidic loam (670 ± 30 g C m?2) exceeded that in the calcareous sand (340 ± 40 g C m?2) although the soil produced less biomass. The mineralization of native organic C accounted for 700 ± 90 g C m?2 in the acidic loam and for 2800 ± 170 g C m?2 in the calcareous sand. Unfavourable conditions for mineralization and a greater physico‐chemical protection of C by clay and oxides in the acidic loam are probably the main reasons for these differences. The organic C content of the acidic loam was 230 g C m?2 more under the large than under the small N treatment. As suggested by a negligible impact of N inputs on the fraction of new C in the acidic loam, this increase resulted mainly from a suppressed mineralization of native C. In the calcareous sand, N deposition did not influence C concentrations. The impacts of CO2 enrichment on C concentrations were small. In the uppermost 10 cm of the acidic loam, larger CO2 concentrations increased C contents by 50–170 g C m?2. Below 10 cm depth in the acidic loam and at all soil depths in the calcareous sand, CO2 concentrations had no significant impact on soil C concentrations. Up to 40% of the ‘new’ carbon of the acidic loam was found in the coarse sand fraction, which accounted for only 7% of the total soil volume. This suggests that a large part of the CO2‐derived ‘new’ C was incorporated into the labile and easily mineralizable pool in the soil. 相似文献
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Falush D Wirth T Linz B Pritchard JK Stephens M Kidd M Blaser MJ Graham DY Vacher S Perez-Perez GI Yamaoka Y Mégraud F Otto K Reichard U Katzowitsch E Wang X Achtman M Suerbaum S 《Science (New York, N.Y.)》2003,299(5612):1582-1585
Helicobacter pylori, a chronic gastric pathogen of human beings, can be divided into seven populations and subpopulations with distinct geographical distributions. These modern populations derive their gene pools from ancestral populations that arose in Africa, Central Asia, and East Asia. Subsequent spread can be attributed to human migratory fluxes such as the prehistoric colonization of Polynesia and the Americas, the neolithic introduction of farming to Europe, the Bantu expansion within Africa, and the slave trade. 相似文献
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Long‐term soil acidification leads to lower pH values and to a concomitant decrease in base saturation (BS). The relationship between pH and base saturation (BS) in acidified forest soils can be disturbed by processes such as nutrient cycling by vegetation, temporary saturation by ground water that comes into contact with calcareous material, or by upward diffusion of base cations from deeper horizons. This paper examines the relationship between pH and BS in Swiss forest soils developed from calcareous and noncalcareous parent material and identifies some of the factors that can affect the BS in the decalcified parts of soils derived from calcareous parent material. The decalcified zone in the latter soils has a higher BS on average compared to soils from noncalcareous parent material, but their pH values are identical. In the pH range 4.0–4.5, the difference in BS may vary by a factor of three. The mean BS in the decalcified zone tends to decrease with increasing depth of the calcareous layer. The water regime also affects the BS in soils on calcareous parent material. In soils temporarily saturated by groundwater (gleysols), the BS in the decalcified zone is always high (85%–100%) because of the continuous contact between the soil water and the calcareous parent material. In addition, the inhibited drainage impedes the depletion of base cations in these soils. In contrast, soils that are temporarily saturated by rainwater are depleted in base cations due to the alternating wetting‐and‐drying regime and the associated leaching of dissolved ions. In such soils, the depletion of base cations is strongly related to the extent of hydromorphy. Stagnogleyic soils, with the longest period of water saturation, have the highest depletion levels. We conclude that in such soils, the diffusion of base cations from deeper zones is strongly compensated by leaching from the very acidic soil horizons. The pH–base saturation anomaly has consequences for some of the methods used to calculate the critical loads of acidity for forest soils in Switzerland, with many soils being less sensitive than previously reported. 相似文献
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E. Blaser 《Journal of pest science》1961,34(6):89-90
Ohne Zusammenfassung 相似文献
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Erich Blaser 《Journal of pest science》1953,26(2):26-27
Ohne Zusammenfassung 相似文献
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