Spectral dependence of photosynthesis and light absorptance in single leaves and canopy in rose     

Roberta Paradiso  Esther Meinen  Jan F.H. Snel  Pieter De Visser  Wim Van Ieperen  Sander W. Hogewoning  Leo F.M. Marcelis 《Scientia Horticulturae》2011

Little is known about the effects of leaf pigmentation (related to leaf ontogeny), on the spectral dependence of photosynthesis and most observations have been limited so far to single leaves. This study aimed to investigate photosynthesis and the related optical properties of two types of rose leaves, young reddish leaves and middle age green leaves, and to quantify the spectral dependence of photosynthesis at the canopy level.  相似文献   

Impact of DMI and SDHI fungicides on disease control and CYP51 mutations in populations of Zymoseptoria tritici from Northern Europe     

Thies Marten Wieczorek  Gunilla Berg  Roma Semaškienė  Andreas Mehl  Helge Sierotzki  Gerd Stammler  Annemarie Fejer Justesen  Lise Nistrup Jørgensen 《European journal of plant pathology / European Foundation for Plant Pathology》2015,143(4):861-871

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Early detection of sugar beet pathogen Ramularia beticola in leaf and air samples using qPCR     

Thies Marten Wieczorek  Lise Nistrup Jørgensen  Anne Lisbet Hansen  Lisa Munk  Annemarie Fejer Justesen 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(4):775-785

A quantitative PCR method (qPCR) was developed for the detection and quantification of Ramularia beticola causing Ramularia leaf spot in sugar beet. R. beticola specific primers were designed based on the internal transcribed spacer region 2 (ITS2). The assay was applied on DNA extracted from spores trapped on tape from Burkard spore traps placed in an artificially inoculated sugar beet field trial and in two sugar beet fields with natural infections. R. beticola DNA was detected at variable amounts in the air samples 14 to 16 days prior to first visible symptoms. R. beticola DNA was detected in air samples from fields with natural infection at significant and increasing levels from development of the first symptoms, indicating that spore production within the crop plays a major role in the epidemic development of the disease. Sugar beet leaves sampled from the inoculated field trial were also tested with the qPCR assay. It was possible to detect the presence of R. beticola in the leaves pre-symptomatic at least 10 days before the occurrence of the visible symptoms of Ramularia leaf spot. This is the first report of a molecular assay, which allows screening for the presence of R. beticola in plant material and in air samples prior to the appearance of visible symptoms. An early detection has potential as a tool, which can be part of a warning system predicting the onset of the disease in the sugar beet crop and helping to optimise fungicide application.  相似文献   

Trends and drivers of on-farm conservation of the root legume ahipa (<Emphasis Type="Italic">Pachyrhizus ahipa</Emphasis>) in Bolivia over the period 1994/96–2012     

Juan Pablo Rodríguez  Bo Ørting  Christian Andreasen  Sven-Erik Jacobsen  Marten Sørensen 《Genetic Resources and Crop Evolution》2018,65(2):449-469

The leguminous Andean root crop ahipa has become scarce and the current status of in situ conservation in Bolivia is concerning. Agro-biodiversity changes affect the use, conservation and socio-economic trends for ahipa (Pachyrhizus ahipa) and to substantiate this, a comparison of two cropping periods were made. Aspects of root production and the shift from cultivation of ahipa to cash crops such as maize were compared for two periods: (a) 1994/96 and (b) 2012. Our study showed that the price of ahipa had not increased in 70% of the urban markets; hence, there is little incentive to retain the cultivation of ahipa. We found that rural ahipa growers selected the largest seeds, but did not select seeds by colour. The mixed seed colour predominated the conservation of ahipa. Laborious yield enhancing practices required in field management and low market value endanger future conservation of the ahipa. We conclude that additional research is needed in order to safeguard the extant variation of ahipa, i.e. nutritional value, taste, stress tolerance and market potential.  相似文献   

Relaxin: an important indicator of canine pregnancy     

Einspanier A  Bunck C  Salpigtidou P  Marten A  Fuhrmann K  Hoppen HO  Günzel-Apel AR 《DTW. Deutsche tier?rztliche Wochenschrift》2002,109(1):8-12

In the present study the concentration of relaxin in peripheral blood plasma was assessed during canine pregnancy for its suitability as a pregnancy indicator, using a newly developed relaxin enzyme immunoassay. A significant relaxin increase was found in pregnancy at day 24 after ovulation. However, this relaxin increase did not correlate either with litter size or with body weight of the bitch. Induction of abortion with prostaglandin F2 alpha resulted in reduced peripheral relaxin levels, suggesting a damage of the placenta due to this medical intervention. Thus, the results confirm that relaxin, which is produced by the placenta, is a useful marker for early pregnancy diagnosis in the bitch. Relaxin measurement is recommended for detection of pregnancy either alone, or as supplement of ultrasonographic findings.  相似文献   

Quantification of vertical and horizontal transmission of Neospora caninum infection in Dutch dairy herds     

Bartels CJ  Huinink I  Beiboer ML  van Schaik G  Wouda W  Dijkstra T  Stegeman A 《Veterinary parasitology》2007,148(2):83-92

Ninety-six of 108 randomly selected Dutch dairy herds had one or more cows with a positive serostatus for N. caninum. In these 96 herds, we have quantified the probabilities of vertical transmission (VT) and horizontal transmission (HT) of N. caninum infection by combining serostatus and pedigree data in 4091 dam-daughter pairs. The probability of animals infected by vertical transmission during pregnancy (Prob(VT)) was calculated as the proportion of seropositive daughters among daughters of seropositive dams. The probability of animals infected by horizontal transmission (Prob(HT)) was the proportion of seropositive daughters among daughters of seronegative dams. These probabilities were calculated after the frequencies of observed dam-daughter combinations were corrected for (1) imperfect test-characteristics, (2) underestimation of horizontal transmission in situations that seronegative dams were horizontally infected after the birth of their daughters and (3) overestimation of vertical transmission in situations that seronegative daughters born from seropositive dams were horizontally infected. The incidence rate for horizontal transmission was calculated based on Prob(HT) and the average age of the animals in these herds. Based on the analysis of dam-daughter serology, Prob(VT) was 61.8% (95% CI: 57.5-66.0%) and Prob(HT) was 3.3% (95% CI: 2.7-3.9%). After adjusting the observed frequencies for imperfect test-characteristics, underestimation of horizontal transmission and overestimation of vertical transmission, Prob(VT) decreased to 44.9% (95% CI: 40.0-49.9%) while Prob(HT) increased to 4.5% (95% CI: 3.9-5.2%). Prob(HT) corresponded with an incidence rate for horizontal transmission of 1.4 (95% CI: 1.2-1.7) infections per 100 cow-years at risk. When stratifying herds for the presence of farm dogs, Prob(HT) was higher (5.5% (95% CI: 4.6-6.4%)) in herds with farm dogs than in herds without farm dogs (2.3% (95% CI: 1.5-3.4%)). When stratifying for within-herd seroprevalence, Prob(HT) was higher (10.3% (95% CI: 8.6-12.2%)) in herds with high (> or =10%) within-herd seroprevalence compared with herds with low (<10%) within-herd seroprevalence (2.0% (95% CI: 1.5-2.6%)). Although there was this relation between Prob(HT) and within-herd seroprevalence (crude OR(PREV) = 5.7 (95% CI: 4.0-7.9)), in herds without farm dogs, this relationship was no longer statistical significant (OR(PREV|DOG-) = 1.9 (95% CI: 0.7-5.5)). It indicated that the association between seroprevalence and Prob(HT) depended largely on the presence of farm dogs. In addition, when looking for the presence of specific age-groups with significantly higher seroprevalence compared with the rest of the herd, there were 7 herds in which two or more horizontally-infected animals were present in specific age-groups. This was an indication of a recent point-source exposure to N. caninum. These results reiterate the current control strategies to apply strict dog-management measures as well as to minimize within-herd seroprevalence by monitoring serostatus of animals.  相似文献   

Predator removal: effect on fisheries yields in lake victoria (East Africa)     

Marten GG 《Science (New York, N.Y.)》1979,203(4381):646-648

Lake Victoria's artisanal fishery has an overfishing problem. A possible solution is suggested by records showing that fish catches are best where predator populations have been reduced by fishing. It may be possible to remedy overfishing by increasing fishing effort, provided the additional effort is directed toward predators.  相似文献   

Science-policy interface: beyond assessments     

Hulme M  Mahony M  Beck S  Görg C  Hansjürgens B  Hauck J  Nesshöver C  Paulsch A  Vandewalle M  Wittmer H  Böschen S  Bridgewater P  Diaw MC  Fabre P  Figueroa A  Heong KL  Korn H  Leemans R  Lövbrand E  Hamid MN  Monfreda C  Pielke R  Settele J  Winter M  Vadrot AB  van den Hove S  van der Sluijs JP 《Science (New York, N.Y.)》2011,333(6043):697-698

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Titan's atmospheric temperatures, winds, and composition     

Flasar FM  Achterberg RK  Conrath BJ  Gierasch PJ  Kunde VG  Nixon CA  Bjoraker GL  Jennings DE  Romani PN  Simon-Miller AA  Bézard B  Coustenis A  Irwin PG  Teanby NA  Brasunas J  Pearl JC  Segura ME  Carlson RC  Mamoutkine A  Schinder PJ  Barucci A  Courtin R  Fouchet T  Gautier D  Lellouch E  Marten A  Prangé R  Vinatier S  Strobel DF  Calcutt SB  Read PL  Taylor FW  Bowles N  Samuelson RE  Orton GS  Spilker LJ  Owen TC  Spencer JR  Showalter MR  Ferrari C  Abbas MM  Raulin F  Edgington S  Ade P  Wishnow EH 《Science (New York, N.Y.)》2005,308(5724):975-978

Temperatures obtained from early Cassini infrared observations of Titan show a stratopause at an altitude of 310 kilometers (and 186 kelvin at 15 degrees S). Stratospheric temperatures are coldest in the winter northern hemisphere, with zonal winds reaching 160 meters per second. The concentrations of several stratospheric organic compounds are enhanced at mid- and high northern latitudes, and the strong zonal winds may inhibit mixing between these latitudes and the rest of Titan. Above the south pole, temperatures in the stratosphere are 4 to 5 kelvin cooler than at the equator. The stratospheric mole fractions of methane and carbon monoxide are (1.6 +/- 0.5) x 10(-2) and (4.5 +/- 1.5) x 10(-5), respectively.  相似文献   

Testing hypotheses about fecundity, body size and maternal condition in fishes   总被引：6，自引：0，他引：6  

Marten A. Koops  Jeffrey A. Hutchings  & Tara M. McIntyre 《Fish and Fisheries》2004,5(2):120-130

Recent research suggests that maternal condition positively influences the number of eggs spawned in fishes. These studies commonly choose a priori to use body length rather than weight as an explanatory variable of offspring production, even though weight is usually the better predictor of fecundity. We are concerned that consistent exclusion of body weight as a predictor of egg production inflates the variance in fecundity attributable to maternal condition. By analysing data on three populations of Atlantic cod (Gadus morhua, Gadidae) and 10 populations of brook trout (Salvelinus fontinalis, Salmonidae), we illustrate the need for a statistically defensible method of model selection to distinguish the effects of maternal condition on egg production from the effects of body size alone. Forward stepwise regression and null model analyses reveal how length‐based regressions can significantly over‐estimate correlations between condition and fecundity, leading us to conclude that the effect of condition on egg productivity may not be as ubiquitous or as biologically important as previously thought. Our work underscores the need for greater statistical clarity in analyses of the effects of maternal condition on reproductive productivity in fishes.  相似文献