bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absent expression of collagen XVII (BPAG2, BP180) in canine familial localized junctional epidermolysis bullosa
Authors: Olivry Thierry , Poujade‐Delverdier AGNÈS , Dunston Stanley M. , Fine Jo‐David , Ortonne Jean‐Paul 
Published: November 2003

Hereditary junctional epidermolysis bullosa (JEB) represents a subset of mechanobullous diseases associated with defective hemidesmosome/anchoring filament proteins leading to cleavage in the lamina lucida of the epidermal basement membrane. In humans, most cases of JEB have been related to a deficiency of either laminin‐5, collagen XVII (BPAG2, BP180) or integrin β4.We describe the existence of a previously unreported form of familial localized non‐lethal JEB in German Shorthaired Pointer littermates. Acral, auricular and oral erosions and ulcers were observed. Severe ulceration of the footpads was present.Skin biopsy specimens of non‐lesional and lesional skin of affected dogs were screened for a defect in basement membrane proteins using indirect immunofluorescence and immunoperoxidase testing. Epidermal staining for laminin‐5 and integrin α6β4 was similar in affected and normal control dogs. Lack of expression of collagen XVII was uniquely identified in all sections of JEB probands compared with normal control dogs.The defective expression of collagen XVII is likely to be caused by mutation(s) of the COL17A1 gene, as previously reported in humans. This is, to date, the first report of a deficient basement membrane protein in canine JEB.
The effect of different tillage systems on the composition of the seedbank
Authors: FELDMAN S. R. , TORRES C. ALZUGARAY. P. S , LEWIS P. 
Published: November 2003

SummaryThe soil seedbank of a wheat crop grown with four tillage systems (mouldboard plough, disk, chisel and no‐tillage) for 3 years was analysed. Density and composition of seedbanks varied according to tillage system and depth. The mouidboard plough crop had seedbanks with the lowest seed density and there was no difference in density or composition at 0‐5 cm and 5‐10 cm depth whereas no—tillage had a more dense seed bank, especially in the upper part of the soil profile. Diversity of seedbanks also increased from mouidboard plough, to disk, to chisel, to no‐titlage, which had the most diverse bank. Therefore, the data strongly support the hypothesis that the systems causing less disturbance allow the build‐up of a larger and more diverse soil seed bank.
The effect of grazing on seed production in Echium plantagineum
Authors: SMYTH M. J. , SHEPPARD A. W. , SWIREPIK A. 
Published: November 2003

SummaryThis study measured the effect of livestock grazing on the seed production and the seed‐bank of the annual weed, Echium plantagineum L., by comparing six sites across south‐eastern Australia. Maximum taproot diameter predicted seed production of ungrazed plants irrespectiveof site. Seed losses to flowering plants grazed in spring were calculated using the taproot diameter relationship. Moderate continual grazing pressure throughout the seeding period (December‐January) reduced seed production by at least 87%, although grazing was most destructive per unit of time in the first half of this period (peak seed production of the infestation). E. plantagineum has a strong c apacity to compensate for stock grazing should the stock be removed too early. Seedbanks generally increased following significant seed rain, although this trend was not always consistent. In manipulated quadrats, where seed production was reduced by atleast 90% for 4 years, germination of E. plantagineum was lower relative to controls from the second year and the seedbank was 10 times lower when measured in the fourth year. The implications of these results are discussed in relation to existing control strategies for this weed.
Effect of age on the germination of Cassinia arcuata seeds in storage and buried in soil
Authors: CAMPBELL M. H. , NICOL H. I. 
Published: November 2003

SummarySeeds of Cassinia arcuata R. Br. (sifton bush), collected annually from near Orange (1987‐92) and Boorowa (1987‐89). New South Wales. Australia, were stored in a laboratory at a mean temperature of 21°C and a mean relative humidity of 25% and germinated each year for up to 8 years. Seeds from the 1990 and 1992 Orange collections were buried 5 mm and 40 mm deep in the soil for 0.5‐2.7 years and the number and germinability of recovered seeds recorded. Germination capacity of seeds stored in the laboratory increased during the first 2 years of storage and then declined slightly in year 3 and markedly in years 4 and 5 to very low levels in year 6 and subsequent years. The seeds collected near Orange had nil germination after 6 years’storage, whereas Boorowa seeds still had 0.2% and 3.5% germination after 7 and 8 years’storage respectively. Seeds that failed to germinate were shown to be non‐viable by the tetrazolium test. There was no decline in germination rate during the first 3 years of storage, but, thereafter, there was a substantial annual decline, which would reduce the rate of establishment of seedlings in the field and render them susceptible to competition from improved pastures. The longer and deeper the burial of seeds in the soil and the older the seeds, the fewer seeds that germinated when recovered; meaned for both depths of buriai 23% of 0.9‐year‐old seeds that had been buried for 0.5 years and 3.4% of 5.1‐year‐old seeds that had been buried for 2.7 years were recovered in a germinable state. The main causes of loss during burial were germination in the soil and destruction by soil organisms.
Flame weeding: effects of fuel pressure and tandem burners
Authors: ASCARD J. 
Published: November 2003

SummaryThe effects of fuel pressure and burner arrangements using a covered flamer were studied in field experiments on Brassica napus L. and Sinapis alba L. as test species. The responses of the plants to the propane dose and ground speed were described by logistic models. By raising the fuel pressure, the effective speed required to obtain effective control was increased, with a minor increase in effective dose. The use of tandem burners instead of single burners did not increase the effective ground speed and was therefore less energy efficient. Temperatures under the flamer 1 cm above ground were measured by thermocouples in the laboratory. There was a high positive correlation of the maximum temperature or the temperature sum to the reduction of plant biomass in the field. The sigmoidal relation showed that increased temperatures produced an increased control of plants only up to a certain level. Thus, evaluating flame weeders based on temperature measurements alone without knowledge of the relationship between temperature and weed control is not recommended.
Weeds in slash‐and‐burn rice fields in northern Laos
Authors: RODER W. , PHENGCHANH S. , KEOBULAPHA B. 
Published: November 2003

SummarySlash‐and‐burn farmers in northern Laos consider weeds, insufficient rainfall and rodent damage as the most important constraints to upland rice (Oryza sativa L.) production. Labour inputs of 140‐190 days ha‐1 for weed control result in low labour productivity. Average weed cover observed in rice fields was 5.6, 4.1, 2.1, 1.7, 0.7 and 0.7 cm m‐1 (transect) for Chromolaena odorata (L.) King and Robinson, Ageratum conyzoides L., Commelina spp., Lygodium flexuosum (L.) Sw., Panicum trichoides Sw. and Corchorus spp, respectively. Chromoiaena odorata, which was introduced in the 1930s, has become the main fallow species and is considered a desirable fallow plant by most farmers. Average fallow periods reported for the 1950s, 1970s and 1992 were 38, 20 and 5 years respectively. Reduced fallow periods in the last decades have re‐suited in a marked increase in weeding requirements. Above‐ground biomass for rice stem, herbaceous plants and trees after rice harvest was 168, 67 and 60gm‐2 in 1991 and 115, 43 and 24 gm‐2 in 1992. Weeding at 14‐day intervals did not increase rice grain yield.
Weed seed germination after short–term light exposure: germination rate, photon fluence response and interaction with nitrate
Authors: MILBERG P. 
Published: November 2003

SummaryThree laboratory experiments were carried out to answer certain important questions related to the use of‘photo control’as a weed–control strategy. The first experiment documented that seeds of Rumex obtusifolius L. and Silene noctiflora L. germinated more slowly in total darkness than after a short exposure to light, whereas there were no significant differences for Cerastium fontanum Baumg. This suggests that seedling emergence in total darkness would not only result in fewer seedlings, but would also be slower; hence the crop might be given a competitive advantage. The second experiment demonstrated that germination of C. fontanum and S. noctiflora showed a linear response to the logarithm of photon fluence. with levels >1 μmOl m‐2 being stimulatory. This suggests that a near–complete elimination of light during dark harrowing would give the best result. R. obtusifolius, however, had a sigmoid dose–response curve with a lower threshold for germination at 500 μmOl m‐2. Hence, this species had a clear threshold under which unnecessary germination was prevented. The third experiment tested for interaction between light and nitrate in their stimulatory effect on germination percentages. For Descurainia sophia (L.) Webb ex Prantl, R. obtusifolius and Thlaspi arvense L., but not for C. fontanum. such interactions were significant. This stresses the fact that light response will vary substantially depending on the seed's environment.
Reduced efficacy and enhanced degradation of carbetamide after repeated application in Australia
Authors: HOLE S. J. W. , POWLES S. B. 
Published: November 2003

SummaryFollowing reports of poor weed control, the effectiveness of repeated applications of carbetamide atid propyzamide in controlling Lolium rigidum Gaud, (annual ryegrass) was examined under field conditions. Repeated applications of carbetamide or propyzamide were less effective in controlling L. rigidum than an initial application. A single application of carbetamide or propyzamide was sufficient approximately to halve the efficacy of a subsequent treatment with the satne herbicide. Laboratory incubations of soil linked the poor performance of carbetamide upon repeated application to an enhanced deg‐radation rate. We conclude that the repeated application of carbetamide or propyzamide results in less effective weed control under field conditions and that this can be partially avoided by rotation between carhetamide and propyzamide.
Rapid dissipation of atrazine in soils taken from various maize fields
Authors: PUSSEMIER L. , GOUX S. , VANDERHEYDEN V. , DEBONGNIE P. , TRESINIE I. , FOUCART G. 
Published: November 2003

SummaryA laboratory study was carried out in order to measure the degradation rate of atrazine in 36 different soils taken from maize (Zea mays L.) fields in Belgium. These soils differed in their alrazme treatment histories. pH. organic matter content and type of organic and mineral fertili‐zation, Half‐lives of less than 10 days were found in more than 60% of the soils sampled. This rapid dissipation could be linked in a significant way to repeated pretreaiments with atrazine (intensive maize cropping) as well as to higher pH values (from neutral to alkaline), A low organic matter content might also be a factor explaining the rapid degradation of atrazine. but to a lesser extent than the first two factors. On the other hand mineral fertilization was shown to slow down atrazine dissipation. It is hypothesized that repeated treatments of atrazine cause a mi‐crobial adaptation to atrazine degradation and that acidic soil conditions impede this adaptation. To date, this is the first time that evidence for widespread accelerated degradation of atrazine has been reported.
Influence of application rate and manure amendment on cnloridazon dissipation in the soil
Authors: ROUCHAUD J. , NEUS O. , HERMANN O. 
Published: November 2003

SummaryPlots of a sugar beet field in Belgium were treated pre‐emergence with 1.3, 1.95 or 2.6 kg a.i. ha‐1 chloridazon. Some of these plots had been amended 1 month before sowing with 50 1 ha‐1 cow manure. Soil samples were taken al regular intervals and analysed by gas‐liquid chromatography and gas‐liquid chromatography combined with mass spectrometry. During the first month following chloridazon application, soil dissipation followed apparent first‐order kinetics with soil half‐lives being independent of the dose, and were 37 days in the non‐manured plots and 96 days in the manured plots. After the first month, rates of chloridazon soil dissipation increased, giving the same residual chloridazon soil concentration of c. 0.25 mg a.i, kg‐1 in all plots 1.8 months after application. Residual levels remained at this concentration up to the third month after application, and then disappeared, leaving no delectable soil residues at harvest. Chloridazon soil dissipation thus occurred according to unusual kinetics.
Weed seedling emergence and seed survival: separating the effects of seed position and soil modification by tillage
Authors: MOHLER C. L. , GALFORD A. E. 
Published: November 2003

SummaryTillage causes both vertical redistribution of weed seeds and changes in soil physical properties. These two factors are rarely distinguished in studies of the impact of tillage on seedling emergence or seed survival. In this study, seeds of Chenopodium album L., Amaranthus retroflexus L., and Abutilon theophrasti Medik, were planted at particular depths in pots of undisturbed or stirred soil to separate these effects. Emergence and survival data were analysed by non‐linear regression to determine the nature of significant differences between treatments. Emergence increased with slight burial and then decreased exponentially at greater depths. Average emergence over all depths was generally greater in tilled sou than in unfilled soil, particularly for C. album and A. retroflexus. Seed survival approached a maximum with increasing depth. Average survival of seeds that did not produce emerged seedlings was greater in tilled soil than in untilled soil for C. album and A. retroflexus. Thus, tillage affects emergence and seed survival of weeds through changes in soil conditions independently of effects resulting from redistribution of seeds in the soil profile.
Assessment of the sample size to estimate the weed seedbank in soil
Authors: AMBROSIO L. , DORADO J. , DEL MONTE J. P. 
Published: November 2003

SummaryIt was found that, in order to estimate the number of weed seeds in soil with a desirable degree of accuracy and confidence level. the sample size depends to large extent on the spatial distribution pattern of the seeds in the soil. The seeds of most weeds found in cultivated soils are distributed according to one of two statistical distributions: Poisson or Negative Binomial. For an acceptable degree of accuracy in estimating the number of seeds in the soil, the sample size must be large, Taking this into account, in this study a practical solution based on a theoretical approach is proposed for the problem of establishing the sample size for a species distributed according to either statistical pattern. In addition, given the sample size, it was possible to determine the estimation error to be expected. This theoretical approach is compared with that proposed in previous studies. Two abaci, based on simple expressions, are provided to determine the sample size, according to the Poisson or the Negative Binormal distribution of the weed species. For Poisson distribution, the sample size is determined (given the desired maximum relative error estimation and the confidence level) as a function of only one parameter: the expected number of seeds per sampling unit m (estimaied by the sample mean). For Negative Binomial distribution, the sample size is determined as a function of two parameters: m and p (estimated according to the relationship between the sample mean and the sample variance). A sample size n nol very different from those given in previous studies is obtained, but the lower limit found for the n‐values is lower than that found in these studies.
Radiolabelling of isolated cuticles from foliar discs used as a test of cuticle biosynthesis
Authors: CHAMEL A. , VIOUGEAS M. A. , ASSARD N. 
Published: November 2003

SummaryThe radiolabelling of isolaled Hedera helix L, (ivy) leaf cutieles was investigated after incorporation of [14C]acetate in foliar discs Cuticle radioactivity greatly decreased as leaf age inereased. The percentage of radioactivity incorporated in the upper cuticles decreased from 0.5% to 0.08% of the total radioactivity of foliar dises from young to old leaves. Cuticle radioactivity was recovered in waxes, cutin and polar components. It was considerably greater for waxes when expressed in terms of cuticle mass. The methodology was validated using S‐ethyl‐dipropylthiocarbamate (EPTC). The radioactivity incorporation in cuticles was significanly reduced when 1 mm EPTC was deposited as a 20‐μL droplet on lo foliar dises 6 h before the incorporation of radiolabelled acetate. EPTC inhibited radioiabelling of wax and cutin fractions in the upper and lower cuticles. Some acetylenic fatty acid analogues inactivating lauric and oleic acid ω‐hydroxylases, used as acid and sulphonate forms in the same experimental conditions as EPTC, induced no reduction in cuticle radiolabelling. An inhibitory effect was observed only for the acetylenic and the saturated C12 fatty acid analogues, used as tetrabu‐tylammonium sulphonates, when applied directly in the liquid medium supporting foliar dises. Several assumptions are considered to explain the results of the present investigation.
Etude des adventices des vergers d'agrumes dans le Gharb (Maroc): aspects floristique, agronomique et écologique
Authors: BENSELLAM E. H. , BOUHACHE M. , TALEB A. 
Published: November 2003

RésumeA partir de 108 stations dans lesquelles des relevés on été effectués en hiver puis en été dans les vergers d'agrumes de la région du Gharb, 216 espéces adventices appartemant à 47 families botaniques ont été recensées. Les annuelles (76%) et I'élément méditerranéen (54%) sont prépondérants et caractérisenl cette flore. Les notations d'abondance et de fréquence ont permis de dégager 29 espéces ayant une nuisibililé non négligeuble vis à vis des agrumes. Dix de ces espéees sont des géophytes particuliérement redoutables. Les variables édaphiques, texture et teneur en calcaire total, ont été les plus déterminantes pour expliquer la distribution des adventices dans la zone d'étude. La comparaison des diflérentes projections des modalités des facteurs à I'aide de 1′Analyse Factorielle des Correspondances a permis d'individualiser trois groupes homogenes d'especes.
Weeds and weed management in irrigated lentil in northern Sudan
Authors: MOHAMED E. S. , NOURAI A. H. , MOHAMED G. E. , MOHAMED M. I. , SAXENA M. C. 
Published: November 2003

SummaryWeeds are a major constraint to increasing production of lentil (Lens culinaris Medik.) in Sudan, Field studies were conducted to determine the yield loss due to weeds, to identify the critical period of weed interference, to evaluate the activity of different herbicide mixtures in controlting weeds and their selectivity for lentil, and to evaluate different methods of weed control for developing an integrated weed management practice. At Rubatab. unrestricted weed growth accounted for up to 84% loss in yield. The critical period of weed control was between 2 and 4 weeks after sowing. However, a weeding regime experiment at Dongola, a cooler location with a longer growing season, indicated that the critical period was between 4 and 6 weeks after sowing. suggesting that the critical period might vary with the environmental conditions. The herbicides imazethapyr (0.05 kg a.i. ha‐1), terbutryn (1.0 kg a.i. ha‐1) and prometryn (1.0 kg a.i. ha‐1), each in a tank mixture with pendimethalin (1.2 kg a.i. ha‐1), were tolerated by lentil, controlled weeds effectively and significantly increased yields at Wad Hamid. Their efficacy in controlling weeds at Rubatab was low, however, because of the presence of Tephrosia apollinea (Del.) DC. and Melilotus indica (L.) All., which tolerated these herbicides. Efficacy was also reduced in heavier soils. One supplementary hand‐weeding at 4 weeks after sowing enhanced the performance of these herbicides under such conditions. A tank mixture of oxyfluorfen (0.24 kg a.i. ha‐1) with either terbutryn (1.0 kg a.i. ha‐1) or prometryn (1.0 kg a.i. ha‐1) also provided good weed control and increased yield of lentil at Wad Hamid. Application of a higher dose (1.5 kg a.i. ha‐1) of terbutryn and prometryn caused phytotoxicity. Irrigation before seed‐bed preparation reduced grass and broad‐leaved weeds by 58% and 40% respectively, and gave a 30% increase in grain yield over no irrigation. Pre‐emergence application of oxyfluorfen (0.24 kg a.i. ha‐1) and a supplementary hand‐weeding at 4 weeks after sowing gave excellent control of weeds and increased lentil yield by 57% over the weedy control. Thus, use of presowing irrigation, pre‐emergence herbicide and one hand‐weeding form an effective integrated package for controiling weeds in northern Sudan.
Effects of light and mechanical stimulation on coiling and prehaustoria formation in Cuscuta spp.
Authors: HAIDAR M A. , ORR G L , WESTRA P. 
Published: November 2003

SummaryIrradiation of 4‐day‐old dark‐grown seedlings of Cuscuta campestris Yuncker and Cusctira indecara Choisy with I min of red light stimulated coiling and prehaustoria formation in excised upper 4‐cm segments of seedlings during a 48‐h dark period in which zeatin was applied. Coiling and prehaustoria development were completely reversed when irradiated with 2 min of far‐red light applied directly after red light. When deetiolated segments were subjected to prolonged exposure of pure blue light, or mixtures of ultraviolet‐A/far‐red, blue/far‐red or red/far‐red light, coiling and prehaustona development were induced. Blue light at photon fluxes lower than 1 μmol m‐2 s‐1 did not promote coiling and formation of prehaustoria. Mechanical stimulation caused tendrils to coil and form prehaustona in biue and blue/far‐red light, but not in darkness. Zeatin substituted for high irradiance blue light and mechanical stimulation caused coiling and prehaustoria formation.
Assessing the practical importance of weed evolution: a research agenda
Authors: JORDAN N. R. , JANNINK J. L. 
Published: November 2003

SummaryIf food production is to become more sustainable, weed management systems will become subject to many internal and external constraints; these may sharply limit the available range of weed control methods. If so, it will be imperative to preserve efficacy of acceptable weed control methods by defending these against weed adaptation. Moreover, rapid and ongoing weed adaptation may explain the persistent nature of yield losses to weeds despite technological advances. Research is needed to assess the practical importance of ongoing weed evolution. The first step is to determine the risk of rapid weed adaptation to diverse control measures. Experimentally, this risk can be evaluated by determining heritabilities of traits conferring resistance to control measures, and then using ecological genetic methods to measure the actual magnitude of selection for such trails. Models of multivariate trait evolution can be used to determine the net effect of evolutionary forces bearing on weed adaptation to an integrated weed management system (IWMS). It may also be possible to take a preventive approach by designing agricultural systems so that their large‐scale structure impedes weed adaptation to IWMS.