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1.
Docks can be serious weeds of arable land and permanent grasslands where they can persist through well‐established root systems. A Rumex hybrid (R. patientia x R. tianschanicus; cv. OK‐2, Uteusha) has been planted as a forage and energy crop since 2001 in Czechia and has now become a new weed species. As its ecological characteristics are unknown, there is a need for improved knowledge for developing control measures and strategies. In 2010 and 2011, we performed a tube pot experiment to investigate above‐ground and below‐ground biomass growth dynamics and below‐ground biomass allocation of Rumex OK‐2. We compared the hybrid with Rumex crispus and Rumex obtusifolius during the vegetation season in the seeding year. Above‐ground and below‐ground biomass of Rumex species tended to increase from July to September. In the seeding year, flowering was recorded only for one plant of Rumex OK‐2 and 27.5% of R. obtusifolius plants, whereas R. crispus did not flower. The proportion of below‐ground biomass of Rumex species in the upper 30 cm was about 70–80%. The growth dynamics and allocation of below‐ground biomass of Rumex OK‐2 were more like R. crispus than to R. obtusifolius. These similarities indicate the potential of Rumex OK‐2 to become a troublesome weedy species, comparable with R. crispus.  相似文献   

2.
Rumex obtusifolius and Rumex crispus are problematic grassland weedy species, particularly under conditions of organic farming. They are avoided by cattle and horses, but they can be grazed by goats. The aim of this study was to investigate the effectiveness of continuous goat grazing of moderate intensity on R. obtusifolius and R. crispus control. In 2008, 40 seedlings of each species were transplanted into pasture that was grazed by goats (crossbreed Czech white × Czech brown) on the target sward height of 7–10 cm. The number of leaves, proportion of grazed leaves and mortality of plants were monitored over the following 4 years. The number of leaves per plant was higher for R. obtusifolius than for R. crispus. The maximal number of leaves per plant of R. obtusifolius and R. crispus was 10 and 5, respectively. The proportion of grazed leaves was generally higher for R. obtusifolius than for R. crispus and ranged from 10% to 80%. No fertile plant was recorded during the experiment, as goat grazing totally prevented the flowering of both species. The level of mortality of the plants at the start of the fourth grazing season was 70% and 87% for R. obtusifolius and R. crispus, respectively, and no plant survived the fourth grazing season. It was concluded that continuous goat grazing of a moderate intensity that is carried out over 4 years seems to be an effective method for the non‐chemical control of R. obtusifolius and R. crispus in grassland.  相似文献   

3.
A. HONGO 《Weed Research》1989,29(1):7-12
The survival and growth of seedlings of Rumex obtusifolius L. and Rumex crispus L. were investigated from 1982 to 1984. A sward was established by the sowing of seeds of Dactylis glomerata and Trifolium repens and managed under two cutting frequencies. Five hundred seeds of each Rumex species were sown m?2. The total number of emergent seedlings of each Rumex species over two seasons was 230–360 m?2. About 85% of them emerged within 3 months of sowing. Both Rumex species showed the same pattern of survivorship. Survival was clearly enhanced by frequent cutting during the second season. About 20% of the emerged plants survived through to the third season. Plants that emerged during the first season only flowered during the second season. The flowering percentage of total surviving plants was significantly higher in R. obtusifolius than in R. crispus. Rumex obtusifolius was higher in dry matter of aerial parts defoliated during the second season and more individual plants survived through to the third season than for R. crispus. Moreover, dry matter production of grass and clover was depressed by 25–30% in mixtures with R. obtusifolius. compared with production in mixtures with R. crispus.  相似文献   

4.
A. HONGO 《Weed Research》1989,29(1):13-19
A transplant experiment was performed to compare the survivorship of Rumex obtusifolius L. and Rumex crispus L., and also to determine the environmental characteristics of grasslands seriously colonized with R. obtusifolius. One-month-old seedlings of each Rumex species were transplanted into three old reseeded swards with different infestation levels of R. obtusifolius plants. Rumex crispus was absent from all swards. Their survival was monitored at monthly intervals for 4 years (May 1982 to May 1986). The mortality of R. obtusifolius was greater in the third and fourth years in all swards, less than 2% of the phytometers being alive in the fifth spring. The number of R. crispus transplants declined more gradually in the course of the experiment and 4–24% of the phytometers still survived by the end of the experiment. This suggests that R. obtusifolius plants colonized in sown grasslands in the cool-climate region have a comparatively short life expectation of 3–4 years. Mortality rate, growth in size and flowering percentage tended to vary significantly between sites: higher in more productive swards. In years 2 and 3 there were seven-fold differences in mean dry matter weights of plants that produced an inflorescence and those that remained in a vegetative phase. The mortality of transplants was not size dependent in either Rumex species. Phytometers died at random irrespective of the individual sizes.  相似文献   

5.
To understand alterations of oxalate and other metabolite levels induced by aluminium ion (Al3+) stress in Rumex plants, we measured the metabolites in R. obtusifolius using the capillary electrophoresis–mass spectrometry. Oxalate and its precursors (isocitrate and citrate) accumulated in leaves of R. obtusifolius after the Al3+ treatment at pH 4.5. Such increase was not observed under the acidic condition (pH 4.5) without Al3+. Principal component analysis showed organ‐specific changes in metabolite levels in R. obtusifolius by the Al3+ treatment. Highly positive correlations between oxalate and its precursors were revealed by hierarchical clustering and correlation analyses. An increase in oxalate content was consistently observed for three Rumex species (R. obtusifolius, R. crispus and R. japonicus) grown in the presence of Al3+. On the other hand, multivariate analyses revealed the differential alterations of other metabolite levels between R. obtusifolius and the other two Rumex species.  相似文献   

6.
Fresh root fragments of Rumex crispus and Rumex obtusifolius, which initially contain 65–70% moisture, progressively lose moisture when desiccated under conditions matching summer weather in southeast England. The likelihood of shoot emergence and the time it took in glasshouse conditions were both affected by desiccation, with R. crispus the most affected up to 48 hr and R. obtusifolius slower to emerge after 48 hr. These effects converged after longer desiccation periods, and R. crispus entirely failed to emerge after 120 hr. The dry weight of emerged shoots was not significantly different between the species until they were desiccated for 96 hr, after which R. obtusifolius dry weight was significantly reduced. In outdoor trials, desiccation for 24 or 48 hr had a lesser effect on emergence in either species when fragments were planted at the soil surface or at up to a depth of 10 cm, compared to deeper plantings, but emergence was significantly lower in plantings at 15 or 20 cm. Emergence delays were not significantly different between the species until they were planted at 15 or 20 cm, when R. obtusifolius was slower to emerge than R. crispus, an effect exacerbated by increasing desiccation. Similar interactions of increasing soil depth and desiccation were found in reductions in dry weight, number of tillers and leaf area, with R. obtusifolius generally, but not exclusively, better able to withstand more extreme trial conditions. Our findings suggest that control of these highly troublesome weeds can be assisted by appropriate agricultural practices, notably exposing cut fragments to drying conditions followed by deep burial.  相似文献   

7.
J G Zaller 《Weed Research》2004,44(6):414-432
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8.
Rumex crispus L. and R. obtusifolius L. were infected by the rust fungus Uromyces rumicis (Schum.) Wint. Infections caused severe damage to R. crispus. Rusted plants always had a reduced number of leaves and the significant loss of dry weight of roots and leaves amounted to a minimum of 55% compared with controls. Less damage was caused to R. obtusifolilus, but a significant loss of root and leaf dry weight was also observed. These findings support earlier suggestions in the literature that U. rumicis may be able to play a role in controlling docks, which are common weeds in pastures. Effets pathogènes de la rouille Uromyces rumicis (Schum.) Wint. sur Rumex crispus L. et Rumex obtusifolius L. Des Rumex crispus L. et R. obtusifolius L. ont été infectés par la rouille Uromyces rumicis (Schum) Wint. Les infections ont provoqué des dommages importants chez R. crispus. Les plantes infectées avaient toujours un nombre de feuilles réduit, et subissaient au niveau des racines et des feuilles une perte significative de poids sec d'au moins 55% par rapport aux témoins. Les dommages subis par R. obtusifoliusétaient moins importants, mais une perte significative de poids sec des racines et des feuilles a également été observée. Ces résultats confirment la possibilité déjä suggérée dans la littérature que U. rumicis peut être capable de jouer un rôle dans le contrôle des Rumex, qui sont des mauvaises herbes communes dans les prairies. Ueber Schäden an Rumex crispus L. und R. obtusifolius L., verursacht durch den Rostpilz Uromyces rumicis (Schum.) Wint. Rumex crispus L. und R. obtusifolius L. wurden mit dem Rostpilz Uromyces rumicis (Schum.) Wint. infiziert. Die Infektionen verursachten an R. crispus starke Schädigungen. Befallene Pflanzen wiesen eine reduzierte Anzahl Blätter auf. Die signifikante Verringerung des Trockengewichtes von Wurzeln und Blättern betrug mindestens 55% im Vergleich zu unbefallenen Kontrollen. An R. obtusifolius waren die Schäden geringer; aber auch in diesem Fall wurde eine signifikante Reduktion der Trockengewichte von Wurzeln und Blättern beobachtet. Diese Befunde bestätigen frühere Literaturangaben, wonach U. rumicis bei der Bekämpfung von Rumex-Arten, die verbreitete Unkräuter auf Weiden sind, eine Rolle spielen könnte.  相似文献   

9.
Hot‐water treatment of broad‐leaved dock (Rumex obtusifolius) was developed as an alternative to manual digging out in organic farming. During treatment, the top region of the root was heated so that the plants would die back. The aim of this study was to validate the efficacy of the hot‐water treatment of dock roots. The trials were carried out with a commercially available hot‐water high‐pressure cleaner and a rotating nozzle for water application. The target plant control rate assessed 12 weeks after treatment was set at >80%. The appraisal covered 1330 treated plants of varying size from four sites with three different soil texture classes. Parameters which influenced the control rate were water temperature, amount of water, soil moisture and soil texture. Additional parameters recorded were the amount of fuel oil consumption and working time requirements. A reassessment of the plants 1 year after treatment yielded information concerning the ground cover, the possible germination of new dock plants from buried seeds and the soil structure of the site treated. In order to achieve the target control rate of >80%, it is recommended that the temperature of the water leaving the equipment should exceed 80°C. The amount of water required depends on root size and soil moisture. On average, 131 plants per hour can be treated with no negative effects on regrowth or soil structure. Hot‐water treatment is the first functional control alternative to manual digging out R. obtusifolius for organic farming.  相似文献   

10.
Although adult Rumex obtusifolius are problematic weeds, their seedlings are poor competitors against Lolium perenne, particularly in established swards. We investigated the possibility of using this weakness to augment control of R. obtusifolius seedlings with combinations of Gastrophysa viridula (Coleoptera: Chrysomelidae) and the rust fungus Uromyces rumicis. Rumex obtusifolius seedlings were grown in competition with L. perenne sown at different rates and times after R. obtusifolius: they competed successfully with L. perenne when sown 21 days before the grass. Sowing both species at the same time resulted in a dominant grass sward, with R. obtusifolius becoming dominant when sown 42 days prior to L. perenne. Grass sowing rate had no effect on R. obtusifolius growth or biomass. A second experiment investigated how competition from L. perenne sown 21 days after R. obtusifolius combined with damage from G. viridula and/or U. rumicis (applied at either the 3–4‐ or 10–13‐leaf stage, or at both stages) affected the growth and final biomass of R. obtusifolius. Beetle grazing at the latter leaf stage was the only treatment that reduced R. obtusifolius biomass, although rust infection at the earlier application led to an increase in shoot and root weight. The results are discussed in terms of the potential for use of these agents in the field.  相似文献   

11.
The broad-leaved dock (Rumex obtusifolius L.) is widely distributed, and is perceived as a major weed problem in intensively managed permanent grassland. The effects of nitrogen fertilization (120; 240 or 480 kg N ha?1), cutting frequency (every 4 or 6 weeks) and competing grasses on development, dry matter production and stem growth of Rumex were studied under field conditions. Young plants of Rumex were planted into established pure swards of Lolium multiflorum Lam., Lolium perenne L., Alopecurus pratensis L. and Poa pratensis L. In all treatments, only Lolium multiflorum hindered the growth of R. obtusifolius substantially. Cutting intervals of 6 weeks were more favourable to Rumex than were 4-week intervals. Its proportion of herbage yield increased from 2% at 120 kg N ha?1, taken as an average of the three grass swards (Lolium multiflorum not included), to 18% at 480 kg N ha?1. The reproductive capacity of Rumex was greatly influenced by the competing grass species: in the P. pratensis sward, Rumex developed up to 12.3 stems with inflorescences per plant per year, but only 0–9 stems developed in the L. multiflorum plots. The regrowth potential of R. obtusifolius after intense shoot competition and low interception of radiation was unexpectedly high. It is concluded that established dock plants cannot be controlled to any extent by strong competition of grasses, by variation in cutting frequency or by nitrogen fertilization. Effet de la fertilisation azotée et de la fréquence de coupe sur la compétitivité et la capacité de repousse de Rumex obtusifolius L. dans plusieurs pelouses de graminées Rumex obtusifolius L. est largement répandu, et il est considéré comme un problème majeur dans les prairies spermanentes intensives. Les effets de la fertilisation azotée (120, 240 ou 480 kg N ha?1), de la fréquence de coupe (Chaque 4 ou 6 semaines) et des graminées en compétition sur le développement, la production de matière sèche et la croissance de la tige de Rumex ont étéétudiées en plein champ. Des jeunes plantes de Rumex ont été plantées dans des gazons purs de Lolium multiflorum Lam., Lolium perenne L., Alopecurus pratensis L., et Poa pratensis L. De tous les traitements, seul Lolium multiflorum entrave subtantiellement la croissance de R. obtusifolius. Les intervalles de coupe de 6 semaines sont plus favorables au Rumex que ceux de 4 semaines. Sa proportion du rendement en herbe passe de 2%à 120 kg N ha?1 (moyenne des 3 gazons sans Lolium multiflorum), à 18%à 480 kg N ha?1. La capacité de reproduction de Rumex est fortement influencée par l'espèce de graminée en compétition: pour le P. pratensis, le Rumex a développé jusqu'à 12,3 tiges avec inflorescence par plante et par an, et seulement 0,9 pour les parcelles L. multiflorum. Le potentiel de reprise de R. obtusifolius après une forte compétitivé aérienne et une faible interception des radiations a étéétonnamment élevé. On conclut que l'extension d'un Rumex installé ne peut être combattue par une forte compétition des graminées, la variation dans la fréquence de coupe ou la fertilisation azotée. Einfluss der Stickstoffdüngung und der Schnitthäufigkeit auf die Konkurrenz von Rumex obtusifolius L. in verschiedenen Grasbeständen Der Stumpfblättrige Ampfer (Rumex obtusifolius L.) stellt auf intensiv bewirtschafteten Dauerwiesen ein wichtiges Unkraut dar. Der Einfluss der Stickstoffdüngung (120, 240 oder 480 kg N ha?1), der Schnitthäufigkeit (alle 4 oder 6 Wochen) und konkurrierender Gräser wurde im Freiland auf die Entwicklung, die Trockensubstanzproduktion und das Sprosswachstum von Ampfer untersucht. Junge Ampferpflanzen wurden in etablierte Reinbestände von Lolium multiflorum Lam., Lolium perenne L., Alopecurus pratensis L. und Poapratensis L. gepflanzt. Nur Lolium multiflorum vermochte das Wachstum von Ampfer wesentlich einzuschränken. Schnittintervalle von 6 Wochen förderten Rumex viel stärker als jene von 4 Wochen. Im Mittel der 3 Grasbestände (ohne L. multiflorum) stieg der Ertragsanteil von Rumex von 2% bei 120 kg N ha?1 auf 18% bei 480 kg N ha?1. Das Reproduktionsvermögen von Rumex wurde durch die konkurrierende Grasart stark beeinflusst, im Poa-pratensis-Bestand bildete Rumex 12,3 blütentragende Stengel pro Pflanze aus, im L. multiflorum-Bestand dagegen nur 0,9. Das Wiederaustrieb-svermögen von R. obtusifolius war nach intensiver Sprosskonkurrenz und niedriger Strahlungsabsorption unerwartet hoch. Aus den Ergebnissen ergibt sich, dass etablierte Ampfer-Pflanzen kaum durch konkurrenzstarke Gräser und durch die Änderung der Schnitthäufigkeit oder Stickstoffdüngung verdrängt werden können.  相似文献   

12.
Broad-leaved dock (Rumex obtusifolius L.) is a troublesome weed that predominantly grows in pastures and grassland. We hypothesised that frequent defoliation of Rumex will, over time, result in a reduction in root weight and leaf area, to the point where the impact on grass production is negligible. In order to investigate this hypothesis, we conducted three experiments. The objective of the first experiment was to perform a preliminary test of the hypothesis, using potted plants growing in the controlled conditions of a glasshouse. This experiment showed a rapid decline in leaf growth in plants that were defoliated weekly. The objective of the second experiment was to test the hypothesis in realistic outdoor conditions while still being able to collect detailed plant growth information. This experiment confirmed the findings of the glasshouse experiment and provided evidence that leaf growth ceased as a result of a dwindling supply of carbohydrate reserves in the root. Defoliated plants did not exhibit increased mortality. Finally, the objective of the third experiment was to test the hypothesis in a commercial pasture where normal field operations, specifically grass harvesting (three times) and slurry injection (twice), were performed. The results of this experiment were consistent with the results of the other two experiments. We conclude that weekly defoliation, maintained for three or more months, is an effective method to control (reduce the impact on grass production), but not kill, R. obtusifolius in pasture.  相似文献   

13.
Es wurden die Monosaccharid-, Disaccharid- und Stärke gehalte in Wurzeln und Spross von Rumex obtusifotius in Abhängigkeit vom Entwicklungsstadium untersucht. Es zeigte sich, dass der Reservestoffwechsel von Rumex obtusifolius durch drei Phasen gekennzeichnet ist. (1) Phase: Die Pflanze treibt nach dem Winter oder nach einem Schnitt aus. In dieser Zeit nimmt der Stärkegehalt in den Wurzeln ab. Es findet keine Einlagerung statt. (2) Phase: Ab etwa 30 em Wuchshöhe der blütentragenden Sprosse beginnt die Einlagerungsphase. Es erfolgi ein sprunghafter Ansiieg der Starkegehalte in den Wurzeln. Die Einlagerungsphase endet ausgangs der Blute mit dem Abschluss der Sprosstreckung. (3) Phase: Die Samen reifen ab, die blütentragenden Sprosse vertrocknen. Der Stärkegehalt der Wurzeln verändert sich nur noch geringfägig. Diese Befunde deuten darauf hin, dass die grösste Menge an Herbiziden vom Typ der Phenoxyverbindungen kurz vor und während der Blüte in die Speicherorgane von R. obtusifolius transportiert werden dürften. Storage metabolism in broad-leaved dock (Rumex obtusifolius) The amounts of monosaccharide, disaccharide and starch present in roots and shoots of Rumex obtusifotlius were investigated together with their relationship to the stage of development of the plant. It was found that storage metabolism of R. obtusifolius is characterized by three phases. Phase 1: the emergence of shoots after the winter or after cutting. During this period the starch content of the roots decreases and no storage lakes place. Phase 2: When the flower-bearing shoots are about 30 cm long. The storage phase now begins and an abrupt increase in the starch content of the roots occurs. The storage phase ends with the opening of the flower after the completion of shoot elongation. Phase 3. The seeds ripen and the flower-bearing shoots wither. Changes in the starch content of the roots are insignificant. These findings indicate that the majority of the phenoxy-type herbicides might well be translocated into the storage organs of R. obtusifolius shortly before and during flowering. Métabolisme des reserves chez la patience sauvage (Rumex obtusifolius) Les teneurs en monosaccharide, en disaccharide et en amidon présentes dans les racines et les pousses de Rumex obtusifolius ont étéévaluées en même temps que leur relation avec le stade de developpement de la plante. Il a été constaté que le métabolisme des réserves chez R. obtusifolius est caractérisé par trois phases: Phase 1: sortie des pousses aprés l'hiver ou après une coupe. Durant cette période, la teneur en amidon des racines décroít et il n'y a pas dc mise en réserve. Phase 2: lorsque les hampes florales ont environ 30 cm de long. La phase de mise en réserve commence alors et un brusque accroissement de la teneur en amidon se produit. La période de mise en réserve se termine avec l'ouverture de la fleur, aprés l'élongation complète de la tige. Phase 3: les semences mûrissent et les hampes florales se fanent. Les changements de teneur en amidon des racines sont insignifiants. Ces résultats montrent que la majorité: des herbicides de la série phénoxy peuvent aisément migrer dans les organes de stockage de R. obtusifolius peu de temps avant la floraison et pendant celle-ci.  相似文献   

14.
Clonal growth and fragment regeneration of Rumex obtusifolius L. were analysed in two dif ferent studies. Clonal growth system was des cribed by a morphological study of underground structure of different-aged individuals, using maximal branching order in the stem system as an age estimator. Glasshouse experiments were conducted, testing the regenerative capacity of different below-ground parts and the estab lishment of above root-collar fragments planted at different depths under contrasting water regimes. Results showed the presence of a ‘phalanx’ type clonal growth system in grassland populations of Rumex. The main structure in volved in clonal growth proved to be the stem system; the region above the root collar was also the only part able to regrow after damage. Stem fragment regeneration occurred to depths of 15 cm, but was prevented in soils maintained at waterlogging and field capacity. The significance of these results in relation to nonchemical con trol of Rumex populations in grasslands is discussed.  相似文献   

15.
Cherry leaf roll virus (CLRV) isolates from Malus domestica, Ribes rubrum, Rubus idaeus, Rumex obtusifolius and Vaccinium darrowii were characterized based on nucleotide sequences of a 371 bp fragment of the 3′ untranslated region (UTR) of their genomic RNAs, symptoms in the herbaceous hosts, Chenopodium amaranticolor, Chenopodium quinoa, Nicotiana benthamiana, Nicotiana occidentalis and Nicotiana tabacum, and seed transmission in N. occidentalis. The different isolates induced a range of localized and systemic disease symptoms, of varying severity, in the herbaceous hosts. The isolates from M. domestica, R. rubrum, R. obtusifolius and V. darrowii all showed greater than 80% seed transmission in N. occidentalis, but no seed transmission was observed for the R. idaeus isolate. Based on symptoms and seed transmission, the isolates appear to be biologically distinct strains of CLRV. Phylogenetic analysis of the nucleotide sequences from the 3′ UTR, commonly used to detect CLRV, showed that four isolates from M. domestica, R. rubrum, R. idaeus and V. darrowii were almost identical but an isolate from R. obtusifolius exhibited a pairwise nucleotide difference of up to 5·4% when compared to these isolates. There was no obvious correlation between sequence differences and symptomatology.  相似文献   

16.
The aim of this experiment was to compare the growth strategies of Rumex obtusifolius L. and Lolium perenne L. at the seedling stage under different constant photon flux densities. Both species were grown simultaneously in growth chambers (20/15°C) at 50, 150 and 500 μmol m?2 s?1 and sampled on six occasions between the 14th and 34th day after seedling emergence. The relative growth rate of R. obtusifolius always exceeded that of L. perenne. R. obtusifolius allocated more dry matter to the leaves, thus resulting in an increase in specific leaf area and, consequently, leaf area ratio. The decrease in the relative growth rate that resulted from reducing the photon flux density from 500 to 50 μmol m?2 s?1 was lower for R. obtusifolius (?38%) than for L. perenne (?53%). The weed was less sensitive that the grass to the reduction in light intensity, mainly because its specific leaf area increased more and because its net assimilation rate decreased less. The results show that seedlings of R. obtusifolius are able to maximize dry matter production at a low photon flux density. This suggests that the establishment of R. obtusifolius seedlings cannot be prevented by the shade of an established sward. Comparaison de la croissance de R. obtusifolius L. et de L. perenne L. sous différentes densités de flux de photons Le but de cet essai était de comparer la stratégie de croissance de plantules de R. obtusifolius et de L. perenne sous différentes densités de flux de photons. Les deux espèces ont été cultivées simultanément en chambres de croissance (20/15°C) à 50, 150 et 500 μmol m?2 s?1 et récoltées à six reprises entre le 14e et le 34e jour après la levee. Le taux de croissance relatif de R. obtusifolius a toujours été supérieur à celui de L. perenne. Nous avons observé chez R. obtusifolius un investissement plus important en matière sèche dans les feuilles ainsi qu'une surface foliaire spécifique et, par conséquent, un rapport surface foliaire/poids sec total plus élevés. La diminution du taux de croissance relatif consécutive à la réduction de la densité du flux de photons de 500 à 50 μmol m?2 s?1 fut plus faible chez R. obtusifolius (?38%) que chez L. perenne (?53%). La dicotylédone a été moins sensible à la réduction de l'intensité lumineuse que la graminée principalement parce que sa surface foliaire spécifique a davantage augmenté et également parce que son taux net d'assimilation a moins diminué. Nos résultats montrent que les plantules de R. obtusifolius sont capables de produire un maximum de matière sèche sous une faible densité du flux de photons. Ils suggèrent que l'implantation de plantules de R. obtusifolius ne peut pas être empêchée par l'effet d'ombrage d'un couvert en place. Vergleich des Wachstums von Rumex obtusifolius L. mit Lolium perenne L. bei verschiedenen Photonen-Bestrahlungsstärken Ziel dieses Versuches war der Vergleich der Wachstumsstrategie der Keimpflanzen von Rumex obtusifolius L. und Lolium perenne L. bei verschiedenen konstanten Photonen-Bestrahlungsstärken. Beide Arten wurden gleichzeitig in Klimakammern (20/15 °C) bei 50, 150 und 500 pimol m?2 s?1 kultiviert, und zwischen dem 14 und 34. Tag nach dem Auflaufen wurden 6 Teilernten genommen. Die relative Wachstumsrate von R. obtusifolius war jener von L. perenne immer überlegen. R. obtusifolius transportierte mehr Trockensubstanz in die Blätter; die spezifische Blattfläche stieg an, und der Anteil Blattfläche an der gesamten Trockensubstanz nahm zu. Wurde die Photonen-Bestrahlungsstärke von 500 auf 50 μmol m?2 s?1 gesenkt, nahm die relative Wachstumsrate bei R. obtusifolius um 38% und bei L. perenne um 53% ab. Der Ampfer reagierte auf die Reduktion der Lichtintensität weniger empfindlich als das Gras, hauptsächlich weil sie ihre spezifische Blattfläche stärker erhöhte und die Nettoassimüationsrate weniger reduzierte. Die Ergebnisse zeigen, daß Keimpflanzen von R. obtusifolius in der Lage sind, auch bei niedrigen Photonen-Bestrahlungsstärken die Trockensubstanzproduktion zu maximieren. Es wird daher vermutet, daß unter dem Schatten eines Pflanzenbestandes das Etablieren der Keimpflanzen von R. obtusifolius nicht verhindert werden kann.  相似文献   

17.
PINO  SANS  MASALLES 《Weed Research》1998,38(1):25-33
The population dynamics of Rumex obtusifolius L. was analysed in a lucerne:winter cereal crop rotation by means of a matrix population model that takes into consideration two crop rotation periods: the lucerne (Medicago sativa L.) cropping period and the cereal cropping period. Several transition matrices based on life-cycle stages were calculated for each cropping period using experimental data and were used in the construction of a model that analyses the population dynamics of R. obtusifolius under different harvest dates and lengths of lucerne cropping periods. Model projections showed that populations of R. obtusifolius increased during the lucerne cropping period regardless of harvest date and decreased during the cereal cropping period. Under a late harvest date, populations decreased at each crop rotation when lucerne was grown for 3 years, remained close to the equilibrium when lucerne was left to grow for 5 years, and increased for longer lucerne cropping periods. In contrast, populations of R. obtusifolius decreased even with a lucerne cropping period of 9 years under an early harvest date. The significance of these results in relation to the biology and the non-chemical control of the species is discussed.  相似文献   

18.
The effects of asulam applied in September 1970 at 0.55, 1.12 and 2.24 kg a.i./ha on Rumex obtusifolius (L.), Lolium perenne (L.), Other grasses and Trifolium repens (L.) growing in two swards in Wales were investigated. Good short-term control of Rumex was achieved by all rates of asulum although regeneration was occurring by the spring following treatment. Dry matter yields of L. perenne were slightly lowered by 2.24 kg a.i./ha 6 weeks after spraying but production in the spring following treatment was substantially greater than on untreated plots. Poa trivialis (L.) and Agrostis stolonifera (L.) were substantially reduced but invasion of the bare spaces by P. trivialis and P. annua (L.) seedlings tended to mask the success of this control. No harmful effects on T. repens were recorded.  相似文献   

19.
The demography of Rumex acetosella ramets and seedlings was monitored within and between blueberry clones over the two‐year lowbush blueberry production cycle in Nova Scotia, Canada. Overwintering ramets constituted the majority (>70%) of the flowering ramet population. A small proportion of ramets emerging in May and June flowered, but no ramets emerging between July and November flowered in the year of emergence. Emergence of new ramets was season‐long and ramet populations were regulated by a cycle of birth and death in each production year. Ramet populations in blueberry patches had higher growth rates and lower mortality than ramet populations in bare soil patches in the non‐bearing year, resulting in large net gains to ramet populations in blueberry patches during this production year. Ramet population growth rates and mortality were similar in blueberry and bare soil patches in the bearing year and net ramet populations declined during this production year. Survival rates of overwintering and new ramets varied, but ramets from both the overwintering and monthly cohorts contributed to a distinct ramet age structure at the end of each season. Seedling survival ranged from 6 ± 6 to 51 ± 12% across sites, and no seedlings flowered in the year of emergence. Transition probabilities of ramets and seedlings were used to develop a life‐cycle model of R. acetosella for the 2‐year lowbush blueberry production cycle. This model has utility in developing new management strategies for R. acetosella in lowbush blueberry.  相似文献   

20.
The ectoparasitic dagger nematodes Xiphinema index and Xiphinema diversicaudatum, often at low numbers in the soil, are vectors of grapevine nepoviruses, which cause huge agronomical problems for the vineyard industry. This study reports a method, based on real‐time PCR, for the specific detection of these species and of the closely related non‐vector species Xiphinema vuittenezi and Xiphinema italiae. Specific primers and TaqMan probes were designed from the ribosomal DNA internal transcribed spacer 1 (ITS1), enabling the specific detection of single individuals of each of the X. index, X. diversicaudatum, X. italiae and X. vuittenezi species whatever the nematode population. The specificity of detection and absence of false positive reaction were confirmed in samples of each species mixed with the three other Xiphinema species or mixed with nematodes representative from other genera (non‐plant‐parasitic Dorylaimida, Longidorus sp., Meloidogyne spp., Globodera spp. and Pratylenchus sp.). The method was shown to be valid for the relative quantification of X. index numbers through its use, from crude nematode extracts of soil samples, in a greenhouse assay of grapevine accessions ranging from highly susceptible to resistant. As an alternative to time‐consuming microscopic identification and counting, this real‐time PCR method will provide a fast, sensitive and reliable diagnostic and relative quantification technique for X. index nematodes extracted from fields or controlled conditions.  相似文献   

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