Effect of competition between Vicia faba and Camelina sativa as a model weed in breeding for organic conditions          下载免费PDF全文

L Ghaouti  A Schierholt  W Link 《Weed Research》2016,56(2):159-167

Weeds can have a detrimental effect on faba bean (Vicia faba) crops in organic farming. Breeding for competitive cultivars is one option for weed control in organic conditions. The aim of this study was to analyse the impact of heterozygosity and heterogeneity levels and plant height on the competitive ability of faba bean genotypes. A set of 24 genotypes, classified as genotype groups (eight inbred lines, eight polycross progenies, two inbred line bulks, two hybrid bulks and four controls), was tested under two treatments: with and without a model weed. Each group of genotypes was equally composed of tall and short genotypes. The competitive ability of the faba bean genotypes was tested with Camelina sativa (false flax) as the model weed in two German locations over the course of 2 years. Yield loss due to weed competition, as recorded per faba bean genotype, was mainly dependent on the heterozygosity level of the genotypes; hybrid bulks were the most competitive genotype group with an average loss of yield of only 6%, whereas the inbred lines were the least competitive genotype group and recorded an average yield loss of 35%. Within the genotype group, no correlations were found between either the yield performance of the genotypes or their plant height and their competitive responses. The competitive ability of faba bean against weeds was mainly determined by their level of heterozygosity; thus, highly heterozygous cultivars should be promoted for breeding.  相似文献   

Factors affecting the relationship between arterial and end-tidal carbon dioxide pressures in the anaesthetised horse     

JE Rainger  CM Dart  NR Perkins 《Australian veterinary journal》2010,88(1-2):13-19

Objective To assess the effects of the duration of anaesthesia, position of recumbency, mode of ventilation, anaesthetic drug protocol, patient age and type of surgical procedure on the usefulness of capnometry as a measure of the partial pressure of arterial carbon dioxide (P_aco ₂) during general anaesthesia in horses. Design A prospective study compared the P_aco ₂ values with those of partial pressure of end-tidal carbon dioxide (ETco ₂) in horses anaesthetised for elective or emergency surgical procedures. The difference between P_aco ₂ and ETco ₂ (P_aco ₂− ETco ₂) and the physiological dead space to tidal volume ratio (V_D/V_T) were calculated. The effects of the study parameters on these variables was determined. Results The agreement between P_aco ₂ and ETco ₂ was poor. P_aco ₂− ETco ₂ and V_D/V_T during the first 60 min of anaesthesia was significantly less than after 60 min of anaesthesia. Mode of ventilation, position of recumbency, anaesthetic drug protocol, patient age and type of procedure did not have a significant affect on either value. Conclusions P_aco ₂− ETco ₂ in anaesthetised horses can be large, making ETco ₂ unreliable as a predictor of P_aco ₂ and for assessment of pulmonary ventilation. For anaesthesia lasting less than 60 min at least one blood gas analysis of an arterial blood sample is required to assess P_aco ₂− ETco ₂. Arterial blood gas analysis should be repeated after 60 min of general anaesthesia.  相似文献   

Trophic role of Atlantic cod in the ecosystem     

Jason S. Link  Bjarte Bogstad  Henrik Sparholt  & George R. Lilly 《Fish and Fisheries》2009,10(1):58-87

As the world's oceans continue to undergo drastic changes, understanding the role of key species therein will become increasingly important. To explore the role of Atlantic cod ( Gadus morhua Gadidae) in the ecosystem, we reviewed biological interactions between cod and its prey, predators and competitors within six ecosystems taken from a broad geographic range: three are cod-capelin ( Mallotus villosus Osmeridae) systems towards cod's northern Atlantic limit (Barents Sea, Iceland and Newfoundland–Labrador), two are more diverse systems towards the southern end of the range (North Sea and Georges Bank–Gulf of Maine), and one is a species-poor system with an unusual physical and biotic environment (Baltic Sea). We attempt a synthesis of the role of cod in these six ecosystems and speculate on how it might change in response to a variety of influences, particularly climate change, in a fashion that may apply to a wide range of species. We find cod prey, predators and competitors functionally similar in all six ecosystems. Conversely, we estimate different magnitudes for the role of cod in an ecosystem, with consequently different effects on cod, their prey and predator populations. Fishing has generally diminished the ecological role of cod. What remains unclear is how additional climate variability will alter cod stocks, and thus its role in the ecosystem.  相似文献   

Nutrient concentration dynamics in an inland Pacific Northwest watershed before and after timber harvest     

J.A. Gravelle  G. Ice  T.E. Link  D.L. Cook 《Forest Ecology and Management》2009

The nutrient loads of water draining forested watersheds are generally lower than the loads in water draining basins with other dominant land uses. Commercial forest management activities including timber harvesting, site preparation, road construction, and maintenance can alter the chemical properties of headwater forest streams, and there are concerns this can result in cumulative effects at downstream locations. Monthly water samples were collected from 1992 to 2006 in the Mica Creek Experimental Watershed (MCEW) in northern Idaho. This period of record included a pre-treatment time interval from 1992 to 1997; post-road construction period from 1997 to 2001; and post-harvest period from 2001 to 2006. Samples were analyzed for total Kjeldahl nitrogen (TKN), total ammonia nitrogen (TAN), nitrate + nitrite (NO₃ + NO₂), total phosphorus (TP), and orthophosphate (OP). Statistically significant increases (p < 0.001) were observed in NO₃ + NO₂ concentrations following both clearcut and partial cut harvest practices. Downstream of the clearcut harvest activity, mean monthly increases of 0.29 mg-N L⁻¹ were observed. Statistically significant increases were also observed at sites further downstream, but changes were smaller than those immediately below the harvest sites and reflected dilution and possibly instream processing and/or uptake. Continued monitoring at these sites will help evaluate nutrient concentration trends during stand regrowth and hydrologic recovery.  相似文献   

Cold air drainage and modeled nocturnal leaf water potential in complex forested terrain     

Hubbart JA  Kavanagh KL  Pangle R  Link T  Schotzko A 《Tree physiology》2007,27(4):631-639

Spatial variation in microclimate caused by air temperature inversions plays an important role in determining the timing and rate of many physical and biophysical processes. Such phenomena are of particular interest in mountainous regions where complex physiographic terrain can greatly complicate these processes. Recent work has demonstrated that, in some plants, stomata do not close completely at night, resulting in nocturnal transpiration. The following work was undertaken to develop a better understanding of nocturnal cold air drainage and its subsequent impact on the reliability of predawn leaf water potential (Psi(pd)) as a surrogate for soil water potential (Psi(s)). Eight temperature data loggers were installed on a transect spanning a vertical distance of 155 m along a north facing slope in the Mica Creek Experimental Watershed (MCEW) in northern Idaho during July and August 2004. Results indicated strong nocturnal temperature inversions occurring from the low- to upper-mid-slope, typically spanning the lower 88 m of the vertical distance. Based on mean temperatures for both months, inversions resulted in lapse rates of 29.0, 27.0 and 25.0 degrees C km(-1) at 0000, 0400 and 2000 h, respectively. At this scale (i.e., < 1 km), the observed lapse rates resulted in highly variable nighttime vapor pressure deficits (D) over the length of the slope, with variable impacts on modeled disequilibrium between soil and leaf water potential. As a result of cold air drainage, modeled Psi(pd) became consistently more negative (up to -0.3 MPa) at higher elevations during the night based on mean temperatures. Nocturnal inversions on the lower- and mid-slopes resulted in leaf water potentials that were at least 30 and 50% more negative over the lower 88 m of the inversion layer, based on mean and maximum temperatures, respectively. However, on a cloudy night, with low D, the maximum decrease in Psi(pd) was -0.04 MPa. Our results indicate that, given persistent cold air drainage and nighttime stomatal opening, serious errors will result if Psi(s) is estimated from Psi(pd).  相似文献   

Effects of leaf N concentration and leaf area index on determining rice tillering Chinese Rice Research Newsletter     

ZHONG Xuhua  PENG Shaobing  SHEEHY JE  LIU Hongxian 《水稻科学》1999,7(4):8

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Overview on the review articles published during the past 30 years relating to the potential climate change effects on plant pathogens and crop disease risks     

P. Juroszek  P. Racca  S. Link  J. Farhumand  B. Kleinhenz 《Plant pathology》2020,69(2):179-193

From 1988 to July 2019 more than 100 review articles were published, including opinion papers and book chapters, that focused on potential climate change effects on plant pathogens and the future crop disease risks. Therefore, an overview of them is presented herein, particularly helpful for beginners and non-experts in climate change biology research. Specifically, this overview contributes to a faster and more convenient identification of appropriate review articles, for example, related to a certain crop, pathogen, plant disease or country of interest. However, not all important crops, pathogens, diseases and countries are considered specifically and in-depth in any of these review articles, suggesting that there are still research gaps prevalent, which are also highlighted herein. Nevertheless, the overview suggests that researchers are increasingly busy and successful in summarizing the fragmented information spread throughout the international literature. Consequently, they are providing ‘step-by-step’ a comprehensive, in-depth, and continuously updated knowledge platform on potential climate change effects on plant pathogens and the respective crop disease risks in the future, although some aspects will, by nature, be repeated.  相似文献   

Case series of equine pituitary pars intermedia dysfunction in a tropical climate     

CW Spelta  JE Axon 《Australian veterinary journal》2012,90(11):451-456

The clinical manifestations of equine pituitary pars intermedia dysfunction (PPID) in temperate climates are well described. The classic presentation is that of an older animal with hirsutism, laminitis, poor muscle tone, pendulous abdomen and weight loss. This case series highlights the additional clinical signs of anhidrosis and heat stress with secondary exercise intolerance that were seen as primary presenting problems in equids with PPID in the hot, humid conditions of a tropical climate. The clinical signs resolved with medical treatment for PPID.  相似文献   

Diagnosis,treatment and outcomes for koala chlamydiosis at a rehabilitation facility (1995–2005)     

JE Griffith  DP Higgins 《Australian veterinary journal》2012,90(11):457-463

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A new genus of African monkey, Rungwecebus: morphology, ecology, and molecular phylogenetics     

Davenport TR  Stanley WT  Sargis EJ  De Luca DW  Mpunga NE  Machaga SJ  Olson LE 《Science (New York, N.Y.)》2006,312(5778):1378-1381

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