首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Changes in the numbers of Avena fatua seed, incorporated into soil, were monitored in four successive spring barley crops which were harvested early for silage to prevent seed shedding. In the first year there were four times as many seedlings after tine cultivation compared with ploughing, but this was reversed in the second year as re-ploughing brought up dormant seeds and gave more seedlings than tine cultivation. Only 11–14% of the sown seeds produced seedlings during the 4 years. When the seeds were first buried to 25 cm by ploughing, and the barley was direct drilled without cultivation, only 0.4% emerged as seedlings. Few viable seeds remained in the soil after 4 years whether the soil was cultivated annually or not but seed numbers decreased more rapidly with tine cultivation than with ploughing. A few of the deeply buried seeds persisted where the land was direct drilled without cultivation.  相似文献   

2.
An arable field was subdivided and subjected to either deep inversion ploughing or non‐inversion cultivation after viable seeds of Bromus sterilis had been sown into oilseed rape stubble. After sowing in isolated plots distributed within the field, sequences of cropping treatments for the establishment of two successive winter wheat crops were applied. Each subfield was split into an uphill and a downhill direction for soil cultivation. The field had a 10° slope. In the season following seed introduction, 2.6% of the introduced seeds had successfully germinated and established in the non‐inversion cultivation regime, when no effective graminicide was applied. Ploughing eradicated B. sterilis. Using differential global positioning system (DGPS) mapping of the whole field population, emerged plants were observed up to 8.7 m (uphill treatment) and 21.3 m (downhill treatment) of their initial source. The median distance seeds were transported was 2.3 m uphill and 4.8 m downhill. Post‐emergence application of the herbicide propoxycarbazone slightly reduced weed density and seed weight, and almost halved weed seed production. Application of fenoxaprop‐P‐ethyl was followed by higher density of plants, tillers and seeds of B. sterilis. Seed viability was unaffected by herbicide use. Thus, in the second wheat crop following seed rain, the weed population was dispersed more widely in the field, such that 20–30% of seeds were dispersed more than 5 m distance from the first year's foci of infestation. The relevance of soil cultivation to secondary dispersal of B. sterilis is discussed.  相似文献   

3.
Without herbicides, the control of Elymus repens relies on intensive tillage, often in the form of repeated post‐harvest stubble cultivations followed by ploughing. This is costly and time‐consuming and also increases the risk of nitrogen leaching. Our aim was to quantify the controlling effect on E. repens of single and repeated cultivation and differing time of cultivation in relation to spring cereal harvest. A 2‐year experiment was conducted at two sites in the south and east of Sweden in 2011–2012 and 2012–2013. We compared no, single and repeated tine cultivation followed by mouldboard ploughing; the single cultivation was performed directly after harvest or 20 days after harvest; when repeated, the first cultivation was performed immediately or 5 days after harvest, followed by a second cultivation 20 days after harvest. Tine cultivation in combination with mouldboard ploughing resulted in 50–70% lower rhizome biomass, and increased average subsequent cereal yields by 0–130% compared with ploughing alone. Large E. repens populations appeared to be more efficiently reduced by tine cultivation than smaller populations. A single tine cultivation 20 days after harvest tended to result in a higher E. repens shoot density and more rhizome biomass in the subsequent year than tine cultivation directly after harvest. Additional cultivation 20 days after harvest did not improve control of E. repens or the subsequent cereal grain yield, compared with a single cultivation conducted directly after harvest. In conclusion, preventing the growth of E. repens during the early part of the post‐harvest autumn period was more important than starving rhizomes with repeated cultivations.  相似文献   

4.
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   

5.
B. J. WILSON 《Weed Research》1985,25(3):213-219
Avena fatua was sown in a cultivation experiment in the autumn of 3 successive years. For each population seedling emergence and viable seeds in the soil were recorded for 4 years in crops of winter barley in which new seed production was prevented. About half of the seeds sown were recovered after 1 year. In subsequent years viable seeds in the soil declined more rapidly with tine cultivation than with ploughing. After 4 years up to 5% of the original seeds were still viable. One population exhibited greater seed dormancy than the other two populations, due it is thought to higher summer rainfall and the greater availability of moisture during seed maturation. Most seedlings emerged in the autumn and spring, between 12 and 18 months after sowing. A total of 950 seedlings emerged from 12 000 seeds sown; 21% of these seedlings came from new seeds (< 1 year old), 57% from seeds 1–2 years old, 14% from seeds 2–3 years old and 8% from seeds 3–4 years old. Autumn seedlings arose fairly evenly from all age groups while spring seedlings mostly came from the 1–2-year-old seeds. With tine cultivation total seedlings over 4 years represented 9–7% and with ploughing 6–2% of the original seeds sown. A. fatua was more persistent than in previous experiments in spring barley, which suggests that control measures would have to be applied for longer in a succession of winter cereals than spring-sown crops to reduce A. fatua to low populations.  相似文献   

6.
The emergence pattern and life cycle of four major species growing in a non–irrigated almond tree grove were analysed in relation to ploughing frequencies and environmental factors. At the community level, the overall emergence pattern was found to be much the same whether or not the soil was disturbed. Nevertheless, soil disturbance in late winter and early spring produced peaks of seedling emergence and brought about an increase in germination. Winter annuals such as Lolium rigidum Gaudin and Diplotaxis erucoides (L.) DC., which emerged in the autumn, started to grow rapidly in winter and spring and were able to pre–empt the environmental resources of the habitat and suppress spring–germinating plants such as Chenopodium album L. and Amaranthus blitoides S. Watson. Late–winter and early–spring disturbances favoured the dominance of summer annuals such as C. album and A. blitoides S. Watson. The different ploughing regimes applied during the first year had effects on plant development and seed production which brought about changes in plant population size during the second year.  相似文献   

7.
The decline of a population of A. fatua established in September 1971, and not allowed to seed thereafter, was monitored in three successive barley crops Numbers of viable seeds in the son in June fell from 159 m2 in 1972 to 1 m2 in 1974 declining by 83° in the first, and by 96° in the second year. Seedling numbers fell from 138 m2 in 1972 to 9 m2 in 1974, declining by 32° in their first and by 89° in the second year. The slower decline of seedling numbers in the first year was attributed to loss of dormancy of seed reserves giving proportionally more seedlings in the second spring. Cultivations had no major influence on the pattern of seedling emergence in the spring, but they did affect population level. Where the stubble was cultivated immediately after seeding in September 1971, twice as many seedlings and three times as many seeds in the soil were present in 1972 compared with delayed autumn cultivations in 1971. From this greater reserve of seeds in the soil more seedlings arose in 1973 and in 1974. Time cultivation in the winter of 1971 resulted in slightly more seedlings in 1972 than did ploughing; this greater population declined more rapidly with line cultivation in 1973 and 1974. It is suggested that with no herbicidal control annual line cultivation will lead to a more rapid build up than ploughing: where A. fatua is controlled, the decline should be more rapid with tne cultivation. Persistence of A. fatua as a weed in arable situations seems related more to survivors shedding seeds than to the persistence of seeds on the soil. Factors which may influence the persistence of seeds in the soil are discussed.  相似文献   

8.
DIRECT-DRILLING OF CEREALS AFTER USE OF PARAQUAT   总被引：1，自引：0，他引：1  
Summary. Cereal crops were grown at Jealott's Hill in 1962 and 1963 without cultivations, following the use, before drilling, of paraquat to kill unwanted vegetation. This investigation was extended with a series of trials at outside centres. Three trials with winter wheat were drilled in the autumn of 1963, two into pasture and one into stubble. Three barley trials were drilled into stubble in spring 1964.
All the autumn trials and one spring trial compared direct-drilling with normal cultivations at two levels of nitrogen. The other two spring trials compared rates and times of application of paraquat without any plough comparison.
Individual trials showed significant yield differences between direct-drilling and ploughing, but there was no consistent advantage in favour of either technique.
Spraying in advance of drilling generally resulted in similar yields to spraying and drilling on the same day. Winter wheat drilled into pastures showed some retardation of spring growth when spraying and drilling had been carried out on the same day.
When averaged over times of application, yields after spraying paraquat at 2 lb/ac were significantly higher than after 1 lb/ac.
In the trials where two levels of nitrogen were included crops responded to an increase from 60 to 120 units nitrogen/ac as top dressing for winter wheat and from 60 to 90 units nitrogen/ac combine-drilled for spring barley; the response was not always significant.
Semis direct de céréales après application de paraquat  相似文献   

9.
The effects of different populations of volunteer winter wheal and their control with ethofumesate and TCA on growth, seed yield and yield components of S.24 perennial ryegrass were investigated in lield experiments in 1978 and 1979. Reductions in ryegrass seed yield due to the presence of wheat depended on the density of wheat and the number and dry weight of ryegrass tillers. The greatest percentage reduction in ryegrass seed yield occurred at high densities of wheat (300 plants m?2) when the number of ear-bearing tillers and 1000 seed weight of ryegrass were reduced. When Ihe density of wheat was low (80 plants m?2) a smaller reduction in ryegrass seed yield occurred and the number of live wheat plants remaining gradually decreased. Within the range of wheat densities in these experiments (0–300 plants m ?2) a 1% loss in ryegrass seed yield occurred for every 10 wheal plants m?2 present in the crop post winter. Both herbicides caused a reduction in number of ryegrass tillers during growth but, except where TCA was applied at 12 kg ha?1 in November, ryegrass seed yields were not significantly reduced (in comparison with a wheat-free control) and were always greater than those obtained in the presence of wheat where no herbicides had been applied. Levels of volunteer infestation of 300 wheat plants m?2 were controlled with minimum risk of crop damage by applications of 6 kg ha?1 TCA in either October or November, or by application of 1–9 kg ha?1 ethofumesate in November.  相似文献   

10.
分析了土壤理化性质及土壤含水率季节动态,研究了春耕与秋耕分别对草原土壤理化性质的影响。结果表明,秋耕地比春耕地更有利于维护草原土壤的理化性状,同时也更有利于作物的良好生长。因此,在草原干旱区开垦农田,应以秋耕为主要耕作方式。  相似文献   

11.
Effects of ploughing or direct drilling with three methods of straw disposal on amounts of inoculum of Pyrenophora teres , and on frequency of infection and severity of net blotch in the autumn, were studied in winter barley. Prior to ploughing, many conidia of P. teres were caught above areas where infected straw from a previous crop of winter barley had been bated and removed leaving culm bases, or where barley straw had been chopped and left in situ , but relatively few were caught above areas where straw had been burnt. Thereafter, where ploughing had buried surface residues, irrespective of the method of straw disposal, conidia were not caught for at least 3 weeks, and subsequently were substantially fewer than in direct-drilled areas where many spores were caught. Production of conidia (measured as numbers per unit length of straw) was greatest on chopped straw, less on culm bases and least on burnt straw residues. Sporulation on volunteer barley plants was much reduced by application of paraquat + diquat, but some still occurred on visually'dead'volunteer barley.
All direct-drilled barley plants were diseased within 27 days of sowing, whereas 42 days elapsed before all plants sown in ploughed areas were diseased. Disease on individual plants was also more severe in direct-drilled areas: 20% of the area of the first leaf to emerge was diseased 19 days after crop emergence in direct-drilled plots, whereas less than 9% was diseased in ploughed areas 50 days after emergence.
There was an additive effect of straw disposal methods and direct-drilling on disease, which in turn affected plant vigour. The adverse effect of direct-drilling on the incidence and severity of net blotch appeared to be far greater than that of the straw disposal methods.  相似文献   

12.
S. R. MOSS 《Weed Research》1987,27(5):313-320
Alopecurus myosuroides Huds. was studied over a 2-year period in winter wheat established after tine cultivations or direct drilling. Straw was removed by baling or spread and burnt. Seed production was either allowed or prevented by cutting and removing all vegetation at the end of the first year. Cultivation differences had no consistent effect on plant or seed populations. Straw burning destroyed about 50% of seeds and encouraged the germination of surviving seeds. Weed populations in the crop were lower on burnt than on baled areas. Where seed shedding was allowed, populations of seeds in soil and plants increased by up to nine-fold per year. Straw burning resulted in smaller population increases. Seed decline in the soil averaged about 80% per year, so that less than 6% of the weed seeds sown were still viable after 2 years’burial in the soil. Most of the seed decline occurred between July and October and was slightly greater on burnt than on baled areas. Only part of this seed loss was accounted for by germination and emergence of seedlings during summer and autumn. Plants emerging in the crop represented less than 26% of viable seeds present in the soil at time of drilling the crop. Few seedlings emerged in spring. The viability of shed seeds varied with year and with weed density. High infestations were associated with lower seed viability and also fewer heads per plant.  相似文献   

13.
A single dominant mutation conferring resistance to aryloxyphenoxypropionate (AOPP) and cyclohexanedione (CHD) herbicides was incorporated into a quantitative model for the population development of Alopecurus myosuroide s Huds. The model predicts that from an initial seedbank of 100 seed m–2, 10–6 of which mutate to resistance each generation, and annual use of AOPP/CHD herbicides which kill 90% of susceptible but no resistant plants, a threshold of 10 plants m–2 surviving herbicides ('field resistance') will develop: in 9–10 years if all tillage is by tine cultivation to 10 cm deep; after 28–30 years of annual ploughing; in 12 years if tine cultivations are interspersed with ploughing once every 4 years. If AOPP/CHD herbicides are alternated with herbicides with different modes of action, outcomes depend on the annual kill rate: with 95% kill (of susceptible plants by AOPP/CHDs and all plants by alternative herbicides) and tine cultivation, field resistance develops in 22 years; however, resistance can be delayed for 45 years if AOPP/CHDs are rotated with two additional herbicides, each with a different mode of action. The model predictions on the number of years required for field resistance to develop are not highly sensitive to the density of the seedbank or the initial frequency of resistance.  相似文献   

14.
Thlaspi perfoliatum L. is an introduced winter annual that grows in waste places, but it is not a troublesome agricultural weed. Seeds are dormant at maturity in spring, afterripen during summer and germinate in autumn. Non-dormant seeds that fail to germinate in autumn are induced into secondary dormancy by low winter temperatures and cannot germinate the following spring. These seeds afterripen during summer and germinate in autumn if conditions are suitable. Vernalization is not an absolute requirement for flowering. However, it shortens the time to flowering, and vernalized plants produce many more flowers and seeds than non-vernalized plants. Results from studies on seed germination and flowering of T. perfoliatum are compared to published studies on the life cycle of Thlaspi arvense L., an introduced species that is a serious agricultural weed which behaves both as a winter and a summer annual.  相似文献   

15.
Summary. It is practicable to use herbicides as an alternative to ploughing grass swards for the preparation of a seedbed for the sowing of cereals and kale. The yields of spring barley and kale following a glaass/clover sward killed with 10 lb/ac amitrole-T were similar to those obtained following ploughing. Yields of tip to 40 cwt/ac of winter wheat were obtained following grass swards killed with amitrole-T compared with up to 45 cwt/ac after ploughing.
The ideal herbicide must kill all plants in a sward and have no residual toxicity to the subsequent crop. At 10 lb/ac, amitrole-T killed most plants in the sword, but it was considered necessary to delay sowing for at least 3 weeks after spraying to minimize the danger of residual toxicity. Ploughing gave the lowest incidence of grasses persisting from the sward. Paraquat did not control clover and Agropyron repens , while broad-leaved weeds were more common on the ploughed than on the sprayed land.
There were differences in the amount of nitrogen mineralized in ploughed and In undisturbed soil, but these were insufficient to affect crop yields materially. When a lower yield followed herbicidal destruction of the sward, this was not accompanied by a reduced percentage nitrogen content.
L'emploi des déherbants pour la rénovation des prairies  相似文献   

16.
Salsola australis is a widespread annual weed of broad-scale cropping and pasture systems throughout Australia, and is of concern in the wheat belt of Western Australia. The population dynamics of S. australis was monitored at four sites in the Lake Grace district of Western Australia. At all sites, two to three cohorts emerged in summer and autumn or winter. While initial seedling density varied, density-dependent mortality ensured that the total number of senesced plants at each site was not significantly different. Estimated seed production ranged from 95 to 19 596 seeds per plant, although seed viability was low (approximately 9% for seeds that were shed and 15% for seeds that were retained on the mature plants). Total annual seed production per unit area was highly variable within sites but was not significantly different between sites. These data will facilitate the development of improved control strategies for S. australis .  相似文献   

17.
C. M. PIGGIN 《Weed Research》1976,16(5):337-344
Echium plantagineum L. is a widespread, persistent, and often dominant volunteer species in southern Australia. This paper describes laboratory and field experiments investigating seed germination in E. plantagineum and a commonly associated species, Trifolium subterraneum L. In the laboratory, E. plantagineum germination was favoured by relatively high temperatures, and the seed showed considerable innate and temperature-enforced dormancy. In the field, this dormancy appeared to prevent some germination in response to rainfalls immediately after seed formation, and permitted sporadic germination during summer and autumn in subsequent years. In 1972 and 1974, both species emerged well in autumn whilst E. plantagineum was favoured in summer and T. subterraneum was favoured in winter. No seedlings emerged in spring. Emergence appeared to be controlled primarily by moisture availability and temperature but also was affected by cultivation and removal of soil-surface litter. The results of these seed germination studies show that E. plantagineum is well adapted to persist in a Mediterranean-type climate, and will be favoured in years with early seasonal breaks. T. subterraneum is likely to be favoured with later breaks.  相似文献   

18.
A matrix model was constructed for the prediction of vertical seed movement within the soil. This was inserted into a model of the life-cycle of Alopecurus myosuroides in order to predict seed population dynamics. Parameter values were obtained from published sources and from a single field cultivation experiment using coloured plastic beads. In simulations, stability of vertical distribution was reached sooner under ploughing than under rigid tine cultivation. Stable distributions were very different for the two cultivation methods, being reached by damped oscillations in the case of ploughing and asymptotically in the case of rigid tine cultivation.  相似文献   

19.
阿坝州小麦条锈病发生规律的研究   总被引：2，自引：0，他引：2       下载免费PDF全文
1979—1985年在四川省阿坝州越夏区进行条锈病发生规律调查。该地区海拔2900米以上的晚熟小麦约2.5万亩,条锈病持续发生至9月下旬,为自生麦苗和部分早播秋苗提供菌源。自生麦苗的发病面积近3万亩,其中休闲地约2.5万亩,主要分布在松潘、黑水2400—2900米地区,自生麦苗较多,发病较重;荞麦复种地约4000亩,主要分布在黑水、茂汶和汶川等地1700—2500米地带,自生麦苗较少,发病较轻。自生麦苗提供菌源的关键时期是9月上旬至10月下旬。秋苗发病面积约3.7万亩,主要分布在松潘、黑水2700—2950米地带,自9月中旬至12月下旬不断发生流行,而以8月中旬至9月中旬播种的秋苗发病较重,菌源较多,这在越夏菌源传播中起着很重要的作用。条锈菌在阿坝州又可越冬,构成周年侵染循环,常年流行,这不仅严重危害当地小麦生产,而且向广大冬麦区秋苗提供大量菌源。因此,综合治理阿坝州越夏区至关重要。  相似文献   

20.
Summary. Seeds of Avena fatua and A. ludoviciana were sown at a depth of 15 cm or mixed into the top 5 cm of soil in small field-plots at Rothamsted and subjected to 5 different regimes of depth and frequency of cultivation for 3 years, after which all plots were dug to 15 cm in spring and autumn for a further 4 years. Seedlings were counted and no plants were allowed to produce seeds. After 7 years, soil-samples showed that very few intact seeds of A. fatua and none of A. ludoviciana remained, although less than 20% of the seeds sown had produced seedlings. Laboratory tests after 4 to 8 years'dry slorage showed seeds of both species to be viable. The maximum survival of viable seeds, estimated by seedling-emergence, was 61 months for A. fatua and 33 months for A. Indoviciana . Seeds of A. fatua survived slightly longer at 15 cm than in the top 5 cm of soil. Survival of A. ludoviciana was less affected by depth and cultivation, except that birds ate some shallow-sown spikelets in the first fortnight after sowing. A. fatua germinated in spring and autumn, and A. tudoviciana in winter, irrespective of age of seed and cultivation of soil. Frozen soil delayed emergence of A. ludoviciana seedlings lor varying periods between December and March. Seedlings of A. ludoviciana were slightly more winter-hardy than A. fatua . More seedlings of A. fatua appeared in the second spring than at any other time, but 80% of the seedlings of A. ludoviciana appeared in the first autumn and winter.
Effets de la profondeur d'enfouissement des graines et de la fréquence des façons culturalles sur la longévité et la germination des semences de Folle-Avoine (Avena fatua L. et A. ludoviciana Dur .)  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号