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1.
A matrix model of the life cycle of Salsola australis was constructed, based on population ecology data collected from the district of Lake Grace, Western Australia. The model was used to assess potential control strategies for this summer annual weed within the Western Australian broad acre grain cropping system. The population growth rate (λ) of S. australis in the absence of weed control strategies was 1.49 and was virtually unaffected by the dormant seedbank. However, λ increased to 8.21 if it was assumed that a constant number of seed immigrated into the area in question from neighbouring populations of S. australis , through farm-scale seed dispersal. As a result, effective weed management depended on reducing seed dispersal. The model determined that burning all senesced, mobile plants in late autumn, combined with herbicide control of the largest cohorts of S. australis in summer and autumn, reduced population growth rate to 0.79. This control strategy resulted in a 66.1% chance of the population becoming extinct over 25 years. Management strategies are proposed based on the results of the models and further research is required to validate their effectiveness and practicality in the field. 相似文献
2.
The effect of grazing on seed production in Echium plantagineum 总被引：1，自引：0，他引：1
This 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. 相似文献
3.
Common ragweed (Ambrosia artemisiifolia L.) is one of the annual plants that were described recently as invasive weeds in Europe. This species is described as an invasive plant that produces seeds that are highly variable. Its production of variably sized seeds is regarded as promoting its spread in different environments. Experiments were carried out to determine the influence of the seed weight and temperature on germination and the influence of the seed weight and burial depth on seedling emergence. The seeds were divided into a number of classes of weight and the seed weight effect on germination was evaluated by Petri dish assays. In another experiment, the seeds were buried at different depths in a clay soil/sand mix to estimate the burial effect on germination and seedling emergence. The germination level of A. artemisiifolia was high overall, between 76.8% and 94.2%. The seed germination was modified by temperature but it was not influenced by the seed weight. The amounts of germination and seedling emergence were greater for the seeds on the soil surface and decreased with an increasing burial depth, from 2 to 8 cm. No germination or emergence was observed for the seeds that were buried at 10 and 12 cm. The lightest seeds were more sensitive to burial. A greater level of seedling emergence for those seeds that were placed near the soil surface could explain the success of this species in open habitats, where the probability of deeper burial is low. After high seed production, the management of A. artemisiifolia in fields could be partly achieved through soil tillage, burying seeds below 10 cm, and not carrying out deep soil tillage the following year. 相似文献
4.
J. DODD 《Weed Research》1989,29(4):255-263
Production of viable seeds occurred in immature capitula of Silybum marianum following simulated slashing and mowing. In the slashing treatment, capitula with 20 cm or less of stem attached produced viable seeds if cut off when at least half the florets were open, the proportion of viable seeds ranging from 0·3% in capitula at midanthesis to 12% in those at the end of anthesis. Following mowing, viable seeds were produced in full-sized buds which were close to anthesis and in capitula at any stage of anthesis at the time of plant cutting, the proportion increasing from 0·1% in capitula at the start of anthesis to 30% in those at the end. Within a capitulum, anthesis usually lasted five days in irrigated plants. Ripe seeds were released about 17 days later. Seed production averaged 190 seeds for the primary capitulum and 114 in others. In a flowering season starting in early November and lasting about two months, individual plants had the potential to produce an average of 55 capitula, representing an output of 6350 seeds per plant, of which 94% were viable. In view of the prolonged flowering season and the large seed output of S. marianum, it is argued that the restricted period of oviposition by the weevil Rhinocyllus conicus and the low density of larvae per capitulum might limit its impact as a biological control agent for this weed in Australia. 相似文献
5.
The effects of temperature and photoperiod on Emex australis and E. spinosa were studied in a pot experiment. E. spinosa was more precocious than E. australis in terms of earlier flowering, runner and seed formation under conditions similar to those of daylength and mean daily temperatures in the field and it produced three times more seeds. Optimum day/night temperatures for both species, however, were between 15/10 and 20/15°C. Both the lowest (10/5°C) and highest (30/25°C) temperatures tested delayed flowering and there was a terminal necrosis of runners at high temperatures. Flowering in both species also was generally hastened and seed production greater at the longest photoperiod (16 h) compared with the shortest (8 h). The results are discussed in terms of the distribution of E. australis, the similar environmental requirements of both species and the possible encroachment of the less desirable E. spinosa, which is as yet more restricted in distribution in Australia, into areas already colonised by E. australis. 相似文献
6.
Ahmadreza Mobli Sahil Rajpaul Yadav Bhagirath S. Chauhan 《Weed Biology and Management》2020,20(2):38-46
Enhanced crop competition could aid in the management of annual sowthistle (Sonchus oleraceus L.), a dominant weed of Australian cropping systems. A two‐year pot study was conducted to evaluate the effect of wheat (Triticum aestivum L.) planting densities (0, 82, and 164 wheat plants/m2) on growth and seed production of glyphosate‐resistant (GR) and glyphosate‐susceptible (GS) biotypes of annual sowthistle. Without competition, both biotypes produced a similar number of leaves and biomass, but the GS biotype produced 80% more seeds (46,050 per plant) than the GR biotype. In competition with 164 wheat plants/m2, the number of leaves in the GR and GS biotypes was reduced by 62 and 61%, respectively, in comparison with the no‐competition treatment, and similarly, weed biomass was reduced by 78 and 77%, respectively. Compared to no‐competition treatment, the seed production of GR and GS biotypes was reduced by 33 and 69%, respectively, when grown with 82 wheat plants/m2, but increasing wheat density from 82 to 164 plants/m2 reduced the number of seeds only in the GS biotype (81%). Both biotypes produced greater than 6,000 seeds per plant when grown in competition with 164 plants/m2, suggesting that increased crop density should be integrated with other weed management strategies for efficient control of annual sowthistle. 相似文献
7.
The survival of Alopecurus myosuroides Huds. seeds in soil 总被引：1，自引：1，他引：0
S. R. MOSS 《Weed Research》1985,25(3):201-211
The survival of Alopecurus myosuroides seeds was studied in soil under arable cropping and short term grass leys in which seed return was prevented. At two winter wheat sites, where weed seeds were sown, the mean annual seed decline was 73–83% over a 2- or 3-year period. The rate of decline was similar with all the cultivation systems studied: ploughing, tine cultivation and direct drilling. Seeds buried initially by ploughing, and then not disturbed by cultivation, were slightly more persistent. At five arable sites with natural populations of A. myosuroides, seed numbers declined to an average of 3% of the original amount present after 3 years, and to 1% after 4 years. Initial populations of over 50 000 seeds m?2 were recorded. Plant populations were not always proportional to the total seed content of the soil, especially on ploughed land. Seed decline in two grass fields was similar to that under arable cropping. A. myosuroides plants were recorded in a wheat crop following a 2-year grass ley. Weed plants did not persist in the vegetative state in grass used for conservation and grazing. At all sites, appreciable quantities of seeds were still present in the soil after 2–4 years. Although a relatively small proportion of seeds survived, the actual number of seeds surviving was substantial. For this reason, it was concluded that any eradication policy is unlikely to be effective in a cropping system dominated by winter cereals. 相似文献
8.
Solidago canadensis is a noxious invasive species in China. We examined the influences of herbicides on pollen germination and pollen tube growth and the effects of cutting flowers and herbicides on seed production and quality. We also determined the seed production and resource allocation to different organs of S. canadensis after uprooting the plants during their reproductive periods. The main results were as follows: (i) 49% pollen of S. canadensis was able to germinate on an appropriate medium; (ii) compared with paraquat, ethephon and 2,4-D, glyphosate had an ideal inhibitory effect on pollen germination and the formation of seeds of S. canadensis ; (3) cut flowering branches, when placed in water or nutrient solution, were still able to produce viable seeds; (4) resources were allocated more to the inflorescences to facilitate seed maturation after plants were uprooted at the flowering stage. Uprooted flower branches were still able to produce viable seeds, especially those in full flower. Therefore, in order to reduce the seed production of S. canadensis and spread of the species we suggest: (i) apply glyphosate at the flower bud stage, (ii) completely destroy uprooted plants at flowering stages and (iii) avoid using the flowering branches as ornamental materials. 相似文献
9.
Development of integrated weed management strategies is dependent on a thorough knowledge of the demography of individual species. The current research established eight winter or summer weed species in a winter annual wheat cropping system at Wongan Hills, Western Australia, and investigated emergence of the first cohort of each species, survivorship, plant size, seed production and seed shedding over three years (2016–2019). The winter weeds Bromus diandrus and Lolium rigidum emerged at the same time as the wheat crop, and the initial cohort of marked plants had 100% survival to seed production in each year. By comparison, other winter weed species like Hordeum leporinum, Rumex hypogaeus, Sonchus oleraceus and Polygonum aviculare frequently emerged later than the crop and had a lower percentage of plants surviving to seed production. However, individual S. oleraceus and P. aviculare plants had the greatest seed production compared to other species. All winter weeds had variable patterns of seed shedding between years, with the exception of L. rigidum. Summer weed species emerged at the same time, but plants in the initial cohort of each species did not always survive to produce seed. The early emergence and high survivorship of B. diandrus indicates high competitive ability, but shedding commenced at a similar time to L. rigidum and harvest weed seed control may be a viable control method for this species. 相似文献
10.
A note on the dispersal of seeds of blackberry (Rubus procerus P.J. Muell.) by foxes and emus 总被引：1，自引：0，他引：1
The monthly variation in the number of seeds of blackberry (Rubus procerus P. J. Muell.) in fox (Vulpes vulpes) faecal droppings was measured at two sites in Victoria, Australia. The maximum percentage of droppings containing seeds (89% at Dartmouth and 55% at Sherbrooke) and the maximum monthly average for the number of seeds per dropping (570 at Dartmouth and 390 at Sherbrooke) occurred in March. Droppings of emu (Dromaius novaehollandiae) collected at Dartmouth contained a mean of 2460 blackberry seeds per dropping. Blackberry seed obtained from berries, fox droppings and emu droppings was tested for germination over a 1O-month period. Germination commenced in spring and ranged from 22 to 35%. It is concluded that foxes and birds are probably responsible for dispersing blackberry over large areas of Victorian bushland. 相似文献
11.
The viruses, bean yellow mosaic ( BYMV ), Echtes Ackerbohnenmosaik (EAMV) and bean (pea) leaf roll ( BLRV ) reduced seed yield in faba bean particularly when plants were infected at the pre-and mid-bloom stage. EAMV and BYMV , but not BLRV , delayed senescence and increased branching on glasshouse-grown plants so that more inflorescences were produced on diseased plants; most of the additional flower buds necrosed. All three viruses increased the proportion of flower buds that became necrotic thus reducing the number of mature flowers available for pollination. This, together with enhanced abscission of recently set flowers, diminished pod production. Flower set per se was unaffected by infection. The number of ovule sites per pod and weight of individual mature seeds were also unaffected by these diseases but productivity per pod declined because of increased ovule abortions. Patterns of pod production on the inflorescence and location of mature seeds within the pod were unaffected by virus infection. 相似文献
12.
Salsola australis, like other agricultural weed species of the Salsola genus, produces a mobile seedbank. Aspects of this mobile seedbank were investigated in three field trials, including total seed production, rate of seed shedding, rate at which seeds lose germinability and the distance and directionality of plant movement. Total seed production was highly variable (ranging from 138 to 7734 seeds per plant), but was directly related to aboveground plant biomass at maturity. Following senescence, mature plants broke free of their root system and the wind driven plants moved considerable distances (1.6–1247.2 m). Half of the mobile plants moved <100 m, as they became entangled with other S. australis plants within the stand. Seed shedding commenced before the plants became mobile and increased with movement, but was also related to the aging and weathering processes experienced by stationary or mobile plants. All plants retained a proportion of their seed in spite of movement, weathering and ageing of the plants, although germinability of retained seed dropped to <2% after 2 months. Salsola australis engages in broad scale seed dispersal similar to that observed in other species of the Salsola genus, allowing this species to maintain a high rate of invasion and range expansion. 相似文献
13.
The effects of the density and proportion of both volunteer barley ( Hordeum vulgare L.) and Stellaria media (L.) Vill. (common chickweed) on the seed yield of both species was investigated in linseed ( Linum usitatissimum L.) and autumn-sown field bean ( Vicia faba L.). A model was created to estimate these effects. It was a combination of two models. The first was a simple linear model relating weed seed number m2 to weed dry weight m2 . The second was an inverse linear model relating weed dry weight per plant to weed density. A very good relationship existed between barley dry weight and number of seeds m2 and between S. media dry weight and number of seed capsules m2 . This relationship was relatively consistent between experiments. The inverse linear model provided a good estimation of the relationship between weed density and weed dry weight per plant for both barley and S. media . Model variables, however, differed between experiments. Using the combined model it was estimated that, in the absence of other weed species and at a density of 800 plants m2 , S. media would produce between 4000 and 48 000 seeds m2 , whereas volunteer barley, at a density of 400 plants m2 , would produce between 2000 and 8000 seeds m2 . The presence of barley always reduced S. media seed yield and a barley population of 100 plants m2 could reduce S. media seed yield by up to 79%. The presence of S. media reduced barley seed yield in only one of three experiments, in which a S. media density of 800 plants m2 reduced barley seed yield by up to 68%. It was concluded that interspecific weed competition should not be ignored as a factor in models of weed population dynamics 相似文献
14.
M M THOMAS M S WATT§ J JAY† D PELTZER‡ E G MASON¶ M H TURNBULL & D WHITEHEAD‡ 《Weed Research》2009,49(1):67-72
This study aims at quantifying the effects of defoliation on seed production and germination in Buddleja davidii , and determining the potential for reducing the invasive success of the species. The effects of defoliation on seed production and germination at the flower spike and plant levels were investigated for control plants and plants that were defoliated by 66% at monthly intervals from mid-summer (January) to mid-autumn (April). Seed samples for germination were collected in late autumn (May). Defoliation reduced flower spike number per shoot, seed number per flower spike and average seed mass by 9%, 22% and 13% and 30%, 33% and 17% on main and side shoots, respectively. In contrast, emergent leaf area per shoot in the defoliated plants exceeded that for the control plants by 89%. The ratio of total seed mass per plant/emergent leaf area per shoot was significantly lower in the defoliated compared with the control plants by 50%. Defoliation did not affect the timing or rate of seed germination. Defoliation of B. davidii resulted in a marked decrease in reproductive capacity, consistent with the priority allocation of resources to compensational leaf area growth. 相似文献
15.
Biology of Commelina benghalensis L. in south-eastern Queensland. 1. Growth, development and seed production 总被引：2，自引：0，他引：2
Experiments conducted at Kingaroy in southeastern Queensland, investigated growth, development and seed production of Commelina benghalensis L. a weed of field crops, which produces aerial and underground flowers. Plants were grown from four seed types (large and small seeds from the two types of flowers) in pots exposed to the weather and in the field. Development was faster, and growth and seed production were greater in the field than in pots. Plants grown from aerial seeds were smaller, developed aerial flowers earlier, and produced more aerial fruits than plants grown from underground seeds. Rhizomes and underground flowers began to develop 6 weeks after emergence on plants from all seed types, prior to the development of aerial flowers. Seed production in the field was 8000 m?2 for plants grown from underground seeds and 12000 m?2 for plants grown from aerial seeds. Small aerial seeds represented 73–79% of the total seed production, large aerial seeds 19–22%, and underground seeds only 1–3%. 相似文献
16.
通过布设种子收集器收集种子,对收集的种子以时空差异进行分组分析,探讨羽毛针禾[WTBX]（Stipagrostis pennata）[WTBZ]种子散布规律以及古尔班通古特沙漠种群的种子雨特征。结果表明：① 羽毛针禾种子雨的积累密度平均达到3 766.30粒·株-1,其中饱满种子占19.56%;② 种子散布的高峰集中在6月25到7月15日,其落种量占整个种子雨的61.96%,其后种子雨密度随时间逐渐减小;③ 种子雨密度与生境之间均不存在显著性差异;④ 种子雨总量与其年龄之间存在显著性差异;⑤ 种子雨的前扩散过程中种子集中降落在背风方向4 m范围和株丛周围1 m内。古尔班通古特沙漠南缘种子雨虽质量不高,但密度大,对种群的自然更新具有一定的意义。 相似文献
17.
JANA HRDLIČKOVÁ MICHAL HEJCMAN VERONIKA KŘIŠŤÁLOVÁ VILÉM PAVLŮ 《Weed Biology and Management》2011,11(4):190-201
Rumex obtusifolius is believed to be a nitrophilous weedy species that spreads mainly by seed. However, the effects of nutrient availability on seed production never have been investigated. In this study, how the amount of seed production per plant, the chemical composition of the seeds, and their size and germination are affected by the supply of N, P, and K was investigated. A pot fertilizer experiment with 10 treatments (combinations of 0, 150 [N1], and 300 [N2] kg N ha?1, 0, 40 [P1], and 80 [P2] kg P ha?1, and 0 and 100 [K] kg K ha?1 applied twice per vegetation season) was carried out in Prague, Czech Republic, in 2008 and 2009. The seeds from plants that were cultivated since the spring were collected each August. The germination of the seeds was determined in long‐daylight conditions at a stable temperature of 20°C. The number of seeds per plant ranged from 0 in the P1 and P2 treatments and <200 in the control and K treatments to almost 9000 in the N2P2K treatment. The number of seeds per plant was positively correlated with the number of stems per plant and the number of seeds per stem. The relationship between the amount of seeds per plant and the individual seed weight was positive. The concentration of N, P, and K in the seeds was affected by the treatments. The weight of 1000 seeds ranged from 1.3 to 1.7 g. The seed length ranged from 2.11 to 2.34 mm and the seed width varied from 1.26 to 1.42 mm. With the exception of the control (with 94% germination), the amount of seed germination was >98% in all the other treatments in 2008. In 2009, the amount of seed germination was >95% in all the treatments, except N1 and N2, where 93% and 89% germination, respectively, was recorded. The germination rate was positively related to the P concentration in the seeds. The amount of time that was necessary for 50% seed germination ranged from 1.53 to 2.89 days and was not related to the N concentration in the seeds, but it was negatively related to the P and K concentrations. A balanced N, P, and K supply to the mother plant strongly affected the number of produced seeds and their chemical composition and germination ability. 相似文献
18.
S. R. MOSS 《Weed Research》1983,23(1):45-51
Seed shedding from heads of Alopecurus myosuroides occurred from late June to late August at most locations. Most seeds were shed before winter wheat (Triticum-aestivum L.) was harvested hut at two winter barley (Hordeum sativum L.) sites, only 50% of seed was shed prior to harvest. The viability of seeds shed at the start and end of the shedding period tended to be lower than that at peak shedding time in late July and early August. There were large differences between sites in the viability of the total amount of seed shed. The results of viability tests based on the presence of full caryopses and germination in pots of sterile soil were similar. Assessments of head numbers and head length were significantly correlated with total seed production. Head length, but not head number assessments, were also significantly correlated with viable seed production. 相似文献
19.
As herbicide‐resistant weeds have spread in the agricultural fields of grain‐exporting countries, their seeds could be introduced into other countries as contaminants in imported grain. The spread of resistance genes through seed and pollen can cause significant economic loss. In order to assess the extent of the problem, we investigated the contamination by herbicide‐resistant annual ryegrass (Lolium rigidum) of wheat imported from Western Australia into Japan. Annual ryegrass seeds were recovered from wheat shipments and seed bioassays were conducted to identify resistance to the herbicides that are commonly used in Australia: diclofop‐methyl, sethoxydim, chlorsulfuron, and glyphosate. Nearly 4500 ryegrass seeds were detected in 20 kg of wheat that was imported in both 2006 and 2007. About 35% and 15% of the seeds were resistant to diclofop‐methyl, 5% and 6% were resistant to sethoxydim, and 56% and 60% were resistant to chlorsulfuron in 2006 and 2007, respectively. None was resistant to glyphosate in either year. As the contamination of crops by herbicide‐resistant weeds is probably a common phenomenon, the monitoring of incoming grain shipments is necessary to stem the further spread of herbicide‐resistant weeds into importing countries. 相似文献
20.
Nasr H. Gomaa 《Arid Land Research and Management》2019,33(1):70-90
This study explores the effects of year and location on reproductive traits and flowering phenology in Retama raetam populations growing in a hyper-arid environment. Besides year, season, and location, variations in the soil seed bank were also evaluated. Germination percentage of seeds buried in soil at two different depths for one year was determined. I hypothesized that changes in water availability between years and locations would lead to variations in reproductive traits, flowering phenology, and the seed bank of R. raetam. The study was conducted at a midstream and an upstream location during 2013 and 2014 in Wadi Rishrash in the Eastern Desert of Egypt. Flower, fruit, and seed production were significantly higher in the midstream location than the upstream location and in 2014 than in 2013. Flowering onset and duration did not differ significantly between locations. Flowering occurred earlier in 2014 than in 2013 at both locations, and the flowering period was longer in 2014 than in 2013. The size of the seed bank was greater at the midstream than at the upstream location, and in summer than in spring season. Germination of seeds decreased with burial depth, but increased with burial duration. Larger individuals produced more seeds and flowered earlier than smaller plants. The size of plant was also positively correlated with flowering duration. The location and temporal variations in all these traits may be related to environmental differences between locations and differences in annual precipitation. 相似文献