Embryo wastage in the ewe following inductionof ovulation with synthetic gonadotrophin releasing hormone (GnRH)     

SK WALKER  RJ LAMPE  TM HEARD  CD MATTHEWS  RF SEAMARK 《Australian veterinary journal》1990,67(11):415-415

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Serogroups of Australian isolates of Serpulina hyodysenteriae     

DJ HAMPSON  CD MALTAS  CP STEPHENS  K. McKECHNIE  NB BULLER 《Australian veterinary journal》1994,71(10):347-347

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Schizophyllum commune: new mutations in the B incompatibility factor   总被引：6，自引：0，他引：6  

Y Koltin  J R Raper 《Science (New York, N.Y.)》1966,154(748):510-511

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Tillage systems for a cotton–peanut rotation with winter-annual grazing: Impacts on soil carbon, nitrogen and physical properties     

Guillermo Siri-Prieto  D. Wayne Reeves  Randy L. Raper 《Soil & Tillage Research》2007,96(1-2):260-268

Integrating livestock with cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) production systems by grazing winter-annuals can offer additional income for producers provided it does not result in yield-limiting soil compaction. We conducted a 3-year field study on a Dothan loamy sand (fine-loamy, kaolinitic, thermic plinthic kandiudults) in southern Alabama, USA to determine the influence of tillage system prior to cotton–peanut planting on soil properties following winter-annual grazing. Two winter-annual forages [oat (Avena sativa L.) and annual ryegrass (Lolium mutiflorum L.)] and four tillage practices [chisel + disk, non-inversion deep tillage (paratill) with and without disking and no-till] were evaluated in a strip-plot design of four replications. We evaluated cone index, bulk density, infiltration, soil organic carbon (SOC), and total nitrogen (N). Paratilling prior to cotton or peanut planting, especially without surface soil tillage, reduced compaction initially to 40 cm and residually to 30 cm through the grazing period in winter. There were no significant differences in cone index, bulk density, or infiltration between forage species. No-tillage resulted in the greatest bulk density (1.65 Mg m⁻³) and lowest infiltration (36% of water applied), while paratilling increased infiltration in no-tillage to 83%. After 3 years, paratilling increased SOC 38% and N 56% near the soil surface (0–5 cm), as compared to concentrations at the beginning of the experiment, suggesting an improvement in soil quality. For coastal plain soils, integrating winter-annual grazing in a cotton–peanut rotation using a conservation tillage system of non-inversion deep tillage (paratill) with no surface tillage can improve soil quality by reducing cone index, increasing infiltration, and increasing SOC in the soil surface.  相似文献   

Residue and tillage effects on planting implement-induced short-term CO₂ and water loss from a loamy sand soil in Alabama     

S. A. Prior  D. C. Reicosky  D. W. Reeves  G. B. Runion  R. L. Raper 《Soil & Tillage Research》2000,54(3-4):197-199

Recent research indicates tillage operations result in a rapid physical release of CO₂ and water vapor from soil. However, effects of soil disturbance on gas fluxes during planting operations have not been adequately explored. Our objective was to measure short-term gas loss resulting from the use of different planting preparation implements on long-term residue-covered soil (no-till) on a Norfolk loamy sand (Typic Kandiudults; FAO classification Luxic Ferralsols) in east-central Alabama, USA. A crimson clover (Trifolium incarnatum L.) cover crop was killed with herbicide two weeks prior to the study. Due to dry soil conditions, 15 mm of water was applied 24 h prior to study. Gas fluxes were measured with a large canopy chamber (centered over two rows) for an integrated assessment of equipment-induced soil disturbance. Increased losses of CO₂ and water vapor were directly related to increases in soil disturbance. Although these short-term C losses are minor in terms of predicting long-term C turnover in agro-ecosystems, results suggest that selecting planting equipment that maintains surface residue and minimizes soil disturbance could help to conserve soil water needed for successful seedling establishment in these coarse textured soils.  相似文献   

Tomato responses to ammonium and nitrate nutrition under controlled root-zone pH     

Peet MM  Raper CD  Tolley LC  Robarge WP 《Journal of plant nutrition》1985,8(9):787-798

Tomato (Lycopersicon esculentum L. Mill. 'Vendor') plants were grown for 21 days in flowing solution culture with N supplied as either 1.0 mM NO3- or 1.0 mM NH4+. Acidity in the solutions was automatically maintained at pH 6.0. Accumulation and distribution of dry matter and total N and net photosynthetic rate were not affected by source of N. Thus, when rhizosphere acidity was controlled at pH 6.0 during uptake, either NO3- or NH4+ can be used efficiently by tomato. Uptake of K+ and Ca2+ were not altered by N source, but uptake of Mg2+ was reduced in NH4(+)-fed plants. This indicates that uptake of Mg2+ was regulated at least partially by ionic balance within the plant.  相似文献