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1.
Sieglinde S. Snapp Kanchan U. Date William Kirk Katherine O’Neil Amy Kremen George Bird 《Plant and Soil》2007,294(1-2):55-72
Brassica species are increasingly being used as cover crops to suppress soil-borne diseases in potato cropping systems. Experiments
were conducted in controlled environments and in the field to evaluate the effects of cover crop root or shoot or a combination
of root and shoot tissues on potato root and tuber health. In a lab assay we examined the extent to which volatile compounds
released from tissues of two cover crop species, rye (Cereale secale L.) and oriental mustard (Brassica juncea L.), could inhibit mycelium growth of two important potato diseases, Rhizoctonia solani and Pythium ultimum. Twenty-four hours into the lab assay, volatile compounds from all residues suppressed fungal growth. After 48 h, marked suppression
of hyphal growth continued in the presence of mustard residues but not in the presence of rye tissues or the control without
tissues. A 75 L volume container experiment evaluated the effect of incorporating different quantities of mustard shoot and
root tissues (none, comparable to field level and fourfold field level) into R. solani and P. ultimum infested soil on potato growth, root health and tuber disease. In the container study, incorporating mustard shoots at the
highest dose increased potato yield by 54% and reduced disease rating to 2.3 compared to a severe rating of 4.4 in the control.
In the field trial, potato growth, root health and tuber disease levels were evaluated in plots where disease management involved
either incorporation of mustard or rye cover crop roots, shoots and whole plants (roots plus shoots) or standard farmer practice
of a fumigated fallow as a control. White root tissue was used as a health indicator, and averaged 58 and 78% in the fumigated
control and mustard cover crop treatments, respectively. The highest healthy root tissue status (91%) was recorded where whole
plants of mustard were incorporated. In contrast to the visual assessment of root and tuber health, tuber yield in the field
was not influenced by cover crop treatment. Across experiments, the incorporation of or exposure to whole mustard plants was
consistently effective at suppressing soil-borne fungi and promoting healthy roots and tubers, especially at higher rates
of biomass. Mustard should be managed so as to maximize incorporated biomass for effective biofumigation. Multipurpose management
requiring removal of mustard shoots is incompatible with promoting potato rhizosphere health. 相似文献
2.
This research demonstrates the role of antimicrobial volatiles produced by Muscodor albus in disease control in soil and potting mix. The volatiles controlled damping-off of broccoli seedlings when pots containing
soil or soilless potting mix infested with Rhizoctonia solani were placed in the presence of active M. albus culture without physical contact in closed containers. Conversely, plugs of R. solani on potato dextrose agar were inhibited when they were placed in the presence of M. albus incorporated into garden soil or soilless potting mix. Gas chromatographic analysis with solid-phase micro extraction showed
that isobutyric acid and 2-methyl-1-butanol were released from the treated substrates. There was a significant relationship
between the production of isobutyric acid in soil and damping-off control (P = 0.0415). Production of isobutyric acid was short-lived in treated substrates, peaking at 24 h in potting mix and 48 h in
soil. Amounts of isobutyric acid released from soil were several times higher than those released from potting mix. Also,
higher rates of M. albus rye grain culture were required to control damping-off in potting mix than in soil. This suggests that the soil used in this
study is a better environment than soilless potting mix for the biological activity or viability of M. albus and components from the potting mix might bind the volatiles. The release of volatiles from soil during the biofumigation
process suggests that containment measures such as tarping could be used to improve the control of soil-borne diseases and
reduce use rate of the biocontrol agent. 相似文献
3.
The Brassicaceae species Diplotaxis tenuifolia and Brassica nigra contain high concentrations of glucosinolates, the precursors of isothiocyanates (ITCs) that can have biofumigation effects
in amended soils. In a laboratory experiment, incorporation of these plants as green manures into soil was expected to suppress
Rhizoctonia solani AG2-1 (ZG5), the causal agent of damping-off in canola (Brassica napus). The manures were incorporated at 1 (1% w/w) or 5 (5% w/w) g fresh material per 100 g dry soil and incubated for 6 months
at 10, 20, or 30°C and at soil water contents of 10%, 40%, or 70% of water holding capacity. R. solani survived for up to 6 months as a saprophyte in un-amended soil at all soil water contents and at 10 and 20°C. A temperature
of 30°C suppressed R. solani below the level of detection in all treatments after one week. At 1% concentration, the green manures increased the colonisation
of the soil by R. solani, which caused severe damping-off of canola subsequently sown in this soil treatment. Soil amendments at 1% temporarily increased
soil microbial activity. The addition of B. nigra or D. tenuifolia green manure at 5% concentration suppressed the saprophytic growth of R. solani incubated at 10 or 20°C over all soil water contents and significantly increased the microbial activity at all soil temperatures
and water contents. Canola sown into these pots did not succumb to damping-off. The efficiency of hydrolysis of glucosinolates
in the 5% treatment in the first week of incubation ranged from 1.6% for 2-propenyl ITC, extracted from soil containing tissues
of B. nigra, to 3.4% for 3-butenyl ITC extracted from soil containing tissues of D. tenuifolia. 2-propenyl ITC could not be detected after 7 d of incubation. In the longer term (weeks to months), the increase of microbial
activity, caused by adding green manures at 5%, or volatiles from the green manures, most likely played a dominant role in
suppressing R. solani. The impact of ITCs, if any, appears to be short-term (days).
Responsible Editor: Peter A. H. Bakker 相似文献
4.
Gabriele Chilosi Maria Pia Aleandri Natalia Bruni Alessia Tomassini Veronica Torresi Massimo Muganu 《Biocontrol Science and Technology》2017,27(4):539-555
Suppression of root rot diseases of ornamental plants is a potential benefit of formulating soilless container media with compost. A green compost (green nursery compost, GNC), obtained by a circular-economy approach from residues of pruning of woody plants and grass clippings during the nursery activities was analysed for its suppressiveness of root rot diseases using lavender. To this end, a bioassay was develop by formulating potting mixes containing GNC with two rates of peat substitution (25% and 50%) and infested with the root rot pathogens Sclerotinia sclerotiorum, Rhizoctonia solani and Phytophthora nicotianae. Contrasting results were obtained by using both substrates with a significant reduction of root rot by S. sclerotiorum, no effect on the containment of that by P. nicotianae, and an increase of symptoms caused by R. solani. The specific suppressiveness observed may be attributed to the colonisation of compost by specific groups of antagonistic microorganisms. This hypothesis was investigated by the analysis of culturable fungal community, which resulted in the isolation of Trichoderma harzianum and T. atroviride as preponderant fungal species. Trichoderma representative isolates exerted in vitro antagonistic activities against the target pathogens with varying efficiencies indicating the employment of multiple complementary mechanisms, which may have contributed to the observed specific suppressiveness. Both substrates containing GNC resulted suitable for nursery cultivation of lavender, showing a growth performance similar to that obtained with peat-based substrate. Present results indicate that on-farm compost is a suitable component of mixed-peat substrates capable to support plant growth and provide specific disease suppression. 相似文献
5.
Amer F. Mahmoud 《Archives Of Phytopathology And Plant Protection》2016,49(19-20):575-585
Rhizoctonia damping-off caused by Rhizoctonia solani Kühn, is one of the most damaging sugar beet diseases. It causes serious economic damage wherever sugar beets are grown. Biological control is an efficient and environmentally friendly way to prevent damping-off disease. Suppression of damping-off disease caused by R. solani was carried out by four isolates of Bacillus subtilis (Ehrenberg) Cohn as well as three isolates of each of Trichoderma harzianum Rifai and Trichoderma hamatum (Bonord.) Bainier. The effect of Bacillus and Trichoderma isolates against R. solani was investigated in vitro and tested on sugar beet plants under greenhouse conditions. Isolates of Bacillus and Trichoderma were able to inhibit the growth of R. solani in dual culture. Furthermore, Trichoderma isolates gave high antagonistic effect than isolates of B. subtilis. Under greenhouse conditions, coating seeds by T. harzianum and B. subtilis separately, reduced seedling damping-off significantly. However, applications of T. harzianum increased the percentage of surviving plants more than B. subtilis in comparison to control. The obtained results indicate that T. harzianum and B. subtilis are very effective biocontrol agents that offer potential benefit in sugar beet damping-off and should be harnessed for further biocontrol applications. 相似文献
6.
Three mineral oils, BSO, EWOS and E9267 and one vegetable oil (mustard oil), did not appreciably inhibit the mycelial growth of Rhizoctonia solani. However, treatment of 100 g seeds of mung bean with 2 ml EWOS and E9267 oils controlled more than 90% of the pre- and post-emergence damping-off and protected seedlings in soil inoculated with R. solani 5 days after sowing. Soaking seeds in solutions of these oils or drenching the soil did not control damping-off. Mustard oil controlled only pre-emergence damping-off. 相似文献
7.
Brassicaceous cover crops can be used for biofumigation after soil incorporation of the mowed crop. This strategy can be used to manage root-knot nematodes (Meloidogyne spp.), but the fact that many of these crops are host to root-knot nematodes can result in an undesired nematode population increase during the cultivation of the cover crop. To avoid this, cover crop cultivars that are poor or nonhosts should be selected. In this study, the host status of 31 plants in the family Brassicaceae for the three root-knot nematode species M. incognita, M. javanica, and M. hapla were evaluated, and compared with a susceptible tomato host in repeated greenhouse pot trials. The results showed that M. incognita and M. javanica responded in a similar fashion to the different cover cultivars. Indian mustard (Brassica juncea) and turnip (B. rapa) were generally good hosts, whereas most oil radish cultivars (Raphanus. sativus ssp. oleiferus) were poor hosts. However, some oil radish cultivars were among the best hosts for M. hapla. The arugula (Eruca sativa) cultivar Nemat was a poor host for all three nematode species tested. This study provides important information for chosing a cover crop with the purpose of managing root-knot nematodes. 相似文献
8.
Flooding freshly harvested oospores in sterile distilled water (SDW) for several days enhanced germination in 3 out of 4 isolates of Phythium oligandrum. Treatment of SDW-flooded oospores with myo-inositol increased germinability during the first 20 days of storage at 15°C. Seed dressing with oospores of P. oligandrum controlled pre- and post-emergence damping-off of sugar-beet caused by soil-borne P. ultimum and seed-borne Phoma betae. For some isolates, flooded oospores in SDW and treatment with myo-inositol increased efficacy of the seed dressing. However, no significant control of damping-off caused by Rhizoctonia solani was observed. On corn-meal agar, P. oligandrum coiled around and penetrated hyphae of P. ultimum and R. solani, but did not interfere with Ph. betae. 相似文献
9.
The Effect of Glumes on Fungal Infection of Germinating Seed of Spelt (Triticum spelta L.) in Comparison to Wheat (Triticum aestivum L.) 总被引:1,自引:0,他引:1
The influence of fungi on seedling emergence of naked and hulled spelt (Triticum spelta L.) and winter wheat (Triticum aestivum L.) was investigated. Seeds were sown in flat trays and placed in a growth chamber under stress conditions (low temperature and water logging) for four weeks, followed by favourable growth conditions. At weekly intervals, 150 seeds were removed, surface sterilized, and investigated for fungi. Pythium aristosporum Vanterpool, a causal agent of damping-off, was found to be best adapted to the unfavourable conditions and to be a major cause of pre-emergence damping-off. The frequency of seed-borne fungi decreased during the stress period, whereas soil-borne fungi survived and could be isolated from seeds and glumes in the following period with more favourable growth conditions. Seedlings from hulled seeds of spelt emerged more frequently than from naked kernels of spelt and both emerged at a higher rate than from seeds of winter wheat. This is good evidence that glumes protect seeds against fungal colonization and therefore increase the fitness of spelt under unfavourable germinating conditions. 相似文献
10.
Increasing use efficiency of boron fertilisers by rescheduling the time and methods of application for crops in India 总被引:1,自引:0,他引:1
Boron-deficiency is prevalent in light-textured acidic soil regions receiving high precipitation. Crop use efficiency of fertiliser
B is also low under such B-leaching environments. For high leaching regimes, we hypothesised that the optimal timing and method
of B application would vary with the crop sensitivity to B-deficiency and periods of peak demand for B. The aim of the present
experiment was to vary the timing and method of B application to increase use efficiency on typical B-deficient Entisols.
Mustard (Brassica campestris L.), wheat (Triticum aestivum L.) and potato (Solanum tuberosum L.) were the test crops. There were seven treatment combinations of B, applied either to soil or as foliar sprays at different
doses and growth stages of the crops. Biomass and yield related characters of the crops at harvest, B concentration in plants
and its uptake increased with B application being highest in mustard, followed by potato and wheat. Foliar application, in
general had higher economic benefits than soil application. Split application of B either to soil (as basal and 25 days after
sowing) or foliar sprays (at 25 and 40 and 25 and 45 days after sowing for mustard and potato, respectively) had an edge over
a single application. For wheat, a single late application of B (at 45 or 60 days after sowing through soil or foliar spray,
respectively) was more effective than the early or split application in increasing yields. Better use efficiency of B can
thus be achieved if it is applied late for wheat but in splits over a longer period for mustard and potato with higher economic
benefits. 相似文献
11.
Potential phosphorus release from catch crop shoots and roots after freezing-thawing 总被引:1,自引:0,他引:1
Background and aims
Catch crops used for mitigating nutrient losses to water can release phosphorus (P) when exposed to repeated freezing-thawing cycles (FTCs). This study sought to evaluate potential P losses from shoots and roots of eight catch crops.Methods
Shoots and roots sampled from perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), chicory (Cichorium intybus L.), phacelia (Phacelia tanacetifolia L.), red clover (Trifolium pratense L.), white mustard (Sinapis alba L.), oilseed radish (Raphanus sativus var. oleiformis L.) and white radish (R. sativus var. longipinnatus L.) were treated with no freezing, one single FTC, four continuous FTCs and four discontinuous FTCs. All samples were analysed for water-extractable P (WEP), and root samples also for characteristics such as specific root surface area (SSA).Results
Freezing-thawing significantly increased potential P losses from both shoots and roots compared with no freezing. The two radish species and white mustard contained significantly higher concentrations of WEP than the other species, among which chicory and phacelia had the lowest WEP. On average, shoots had 43 % higher WEP than roots. Cumulative P release from shoots and roots was strongly correlated with their total-P content (p?=?0.006 and p?=?0.002, respectively). Cumulative release of P from taproots was correlated with SSA (p?=?0.03).Conclusions
Chicory, and possibly phacelia, appear to be promising catch crops for P. 相似文献12.
Miyada Zamoum Nasserdine Sabaou Florence Mathieu Abdelghani Zitouni 《Biocontrol Science and Technology》2017,27(6):723-738
Rhizoctonia solani is one of the most problematic soil-borne pathogenic fungi for several crop cultures worldwide. This study highlights the effectiveness of high-antagonistic Streptomyces rochei strain PTL2, isolated from root tissues of Panicum turgidum, in controlling the R. solani damping-off and growth promotion of tomato (cv. Marmande) seedlings. The isolate PTL2 was characterised for in vitro biocontrol and plant growth-promoting traits. It exhibited remarkable positive results in all trials, including production of hydrogen cyanide, siderophores, 1-aminocyclopropane-1-carboxylate deaminase and phytohormones, chitinolytic activity and inorganic phosphate solubilisation. PTL2 spores were formulated as wettable talcum powder, sodium alginate pellets and sodium alginate-clay pellets. Their abilities in the biocontrol of R. solani and plant growth promotion were investigated in autoclaved and non-autoclaved soils. Talcum powder and sodium alginate pellets significantly reduced the damping-off severity index compared to a positive control. The talcum powder exhibited the highest protective activity, reducing the disease incidence from 89.3% to 14.1%, whereas chemical seed treatment with Thiram® provided a disease incidence of 16.7%. Furthermore, the talc-based powder formulation resulted in greatest increases in the root length, shoot length and dry weight of seedlings. The interesting biocontrol potential and growth enhancement of tomato seedlings open up promising perspectives for the possible application of talcum powder formulation based on PTL2 spores in crop improvement. 相似文献
13.
Lloyd M. Dosdall Héctor Cárcamo Owen Olfert Scott Meers Scott Hartley John Gavloski 《Biological invasions》2011,13(5):1135-1149
Agroecosystems in the western Canadian provinces of Alberta, Saskatchewan, and Manitoba have been invaded by several alien
herbivorous insects from several orders and families. These species have caused very substantial reductions in yield and quality
of the dominant crops grown in this region, including cereals (primarily wheat, Triticum aestivum L., barley, Hordeum vulgare L., and oats Avena sativa L.), oilseeds (primarily canola, Brassica napus L. and Brassica rapa L., and mustard, Sinapis alba L. and Brassica juncea (L.) Czern.), and pulses (primarily field pea, Pisum sativum L., lentil, Lens culinaris Medik., and chickpea, Cicer arietinum L.). In this study, we used literature searches to identify the major species of insect pests of field crops in western Canada
and determine those species indigenous to the region versus species that have invaded from other continents. We summarize
invasion patterns of the alien species, and some estimated economic costs of the invasions. We document the invasion and dispersal
patterns of the cereal leaf beetle, Oulema melanopus L. (Coleoptera: Chrysomelidae), for the first time in all three provinces. We also report the co-occurrence of its exotic
parasitoid, Tetrastichus julis (Walker) (Hymenoptera: Eulophidae), and implications for classical biological control. We present results of field studies
describing the dispersal patterns of a second recent invader, the pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae). The implications of invasions in this region are discussed in terms of economic and ecological
effects, and challenges posed for pest mitigation. 相似文献
14.
Pythium and Phytophthora species are associated with damping-off diseases in vegetable nurseries and reduce seedling stand and yield. In this study,
bacterial isolates were selected on the basis of in vitro antagonism potential to inhibit mycelial growth of damping-off pathogens
along with plant growth properties for field assessment in wet and winter seasons. We demonstrate efficacy of bacterial isolates
to protect chile and tomato plants under natural vegetable nursery and artificially created pathogen-infested (Pythium and Phytophthora spp.) nursery conditions. After 21 days of sowing, chile and tomato plants were harvested and analysed for peroxidase and
phenylalanine ammonia-lyase activities. Pseudomonas sp. strains FQP PB-3, FQA PB-3 and GRP3 were most effective in increasing shoot length (P > 0.05%) in both artificial and natural field sites. For example, Pseudomonas sp. FQA PB-3 treatment increased shoot length by 40% in the artificial Pythium 4746 infested nursery site in chile plants in the wet season. The bacterial treatments significantly increased the activity
of peroxidase and phenylalanine ammonia-lyase in chile and tomato plant tissues, which are well known as indicators of an
active lignification process. Thus, we conclude that treatment with potential bacterial plant growth promoting agents help
plants against pathogen invasion by modulating plant peroxidase and phenylalanine ammonia-lyase activities. 相似文献
15.
A field experiment was carried out to study the effect of various crop rotations, of high yielding varieties of cereals, pulses, fodders, tubers and oilseeds, on the performance of the crops and the fertility status of the soil over two crop-rotation cycles. The yields of rice (Oryza saliva L.), potato (Solanum tuberosum L.) and onion (Allium cepa) crops were found to be decreasing. The yields of wheat (Triticum aestivum L.) and mustard (Brassica juncea coss), were not affected, while the yield of moong (Phaseolus aureus Roxb.) showed a tendency to increase. Rotations which included berseem (Trifolium alexandrinum) increased the organic carbon content of the soil and there was a slight lowering of the pH with the highest application of phosphatic fertilizer. The accumulation of available potassium was greater in the treatments where the highest amount of fertilizer was applied. The available nitrogen content of the soil increased with application of nitrogen and the balance sheet of nitrogen, phosphorus and potassium showed a positive trend. The continuous cropping of high yielding varieties showed a reduction in the available zinc and iron status of the soil, whereas available manganese and copper increased. The available micronutrients, except manganese, did not correlate significantly with soil pH. 相似文献
16.
Specialty oilseed crops provide an abundant source of pollen for pollinators and beneficial insects 下载免费PDF全文
M. D. Thom C. A. Eberle F. Forcella R. Gesch S. Weyers 《Journal of Applied Entomology》2018,142(1-2):211-222
The continuing pollinator crisis is due, in part, to the lack of year‐round floral resources. In intensive farming regions, such as the Upper Midwest (UMW) of the USA, natural and pastoral vegetation largely has been replaced by annual crops such as maize (Zea mays L.), soyabean (Glycine max L.) and wheat (Triticum spp.). Neither the energy (nectar) nor protein (pollen) needs of pollinating and other beneficial insects are being met sufficiently by the new, high‐intensity, agricultural landscape. Several potentially useful oilseed crops can be grown in the UMW, and many of these oilseeds are highly attractive to beneficial insects. Prior research showed that some of these oilseeds produced abundant nectar, but their corresponding values for pollen production are unknown. Accordingly, the aim of our research was to document pollen (and protein) production per unit area of twelve oilseed crops grown in Minnesota and associate these values with levels of beneficial insect visitation during anthesis. Our results show that oilseed crops such as camelina (Camelina sativa L.), flax (Linum usitatissimum L.) and pennycress (Thlaspi arvense L.) produce relatively little pollen (≤40 kg/ha); borage (Borago officinalis L.), calendula (Calendula officinalis L.), canola (Brassica napus L.), crambe (Crambe abyssianica Hochst) and cuphea (Cuphea viscosissima Jacq. × Cuphea lanceolata W. T. Aiton) produce bountiful pollen resources (50–150 kg/ha); and oilseed echium (Echium plantagineum L.) generates massive amounts of pollen (>400 kg/ha), about 50% of which is protein. Our study is unique in presenting a season‐long perspective of pollen production in alternative oilseed crops, a resource valuable to pollen‐feeding insects such as managed and wild bees. Diversification of UMW landscapes that includes alternative oilseed crops such as oilseed echium and cuphea can potentially provide a ready source of pollen and protein to help combat pollinator decline. 相似文献
17.
Potential trap crops for the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), were evaluated through a series of ovipositional preference and larval survival experiments in outdoor screenhouses in 2002 and 2003. Hosts examined as trap crops were glossy and waxy collards, Brassica oleracea L. variety acephala; Indian mustard, Brassica juncea (L.) Czern; and yellow rocket, Barbarea vulgaris (R. Br.) variety arcuata. More eggs were laid on the potential trap crops, with the exception of waxy collards, than on cabbage. When P. xylostella was offered multiple hosts at the same time, numbers of eggs laid on glossy collards, Indian mustard, and yellow rocket were 3, 18, and 12 times greater than on cabbage, respectively. Similarly, when P. xylostella was offered a single trap crop host and cabbage, numbers of eggs laid on glossy collards, Indian mustard, and yellow rocket were 300, 19, and 110 times greater than on cabbage, respectively. Our studies suggest differences in oviposition between the potential trap crops and cabbage were likely due to host volatiles, leaf morphology and color, or a combination of these factors, rather than to total leaf areas, leaf shape, or plant architecture. Two-choice tests with a Y-tube olfactometer indicated that plant volatiles were major factors in P. xylostella host preference. The percentage larval survival from egg to pupation was 22.2% on cabbage, 18.9% on waxy collards, and 24.4% on Indian mustard, whereas survival was significantly lower on glossy collards (6.7%) and yellow rocket (0%). Based on our tests, it seems that yellow rocket may be the best candidate for use as a trap crop for P. xylostella because it is highly attractive for oviposition, but larvae do not survive on it. 相似文献
18.
The cabbage webworm, Hellula undalis (Fabricius) (Lepidoptera: Pyralidae), a tropical pest on crucifers (Brassicaceae), differentiated among host-plant species for oviposition in laboratory and field tests. White mustard, Sinapis alba (L.) var. Selinda, was the preferred host-plant, followed by Brassica juncea (L.) Czern. et. Coss var. Canadian brown mustard, and pak-choi, Brassica campestris L. ssp. chinensis var. Joi Choi, Black Behi and Bai Tsai. Glucosinolates (GS), secondary plant compounds characteristic to the Cruciferae plant family, and their breakdown products were analyzed by using HPLC and GC-MS-techniques. Species differed in GS composition and concentration. Content of GS was highest in S. alba with progressively lower contents detected in B. juncea and B. chinensis. The aromatic GS, 4-hydroxybenzyl-GS and benzyl-GS, were detected in S. alba. In B. juncea the alkenyl GS, allyl-GS, dominated, whereas in varieties of B. chinensis indolyl and alkenyl GS predominated. Oviposition of H. undalis females on the non-host-plant Vigna unguiculata ssp. sesquipedalis (L.) Fruwirth was stimulated by application of GS extracts from the crucifer species; the extract from S. alba was preferred, followed by extracts from B. juncea and B. chinensis. Hydrolysis of GS in the plant extract from B. chinensis causes loss of the oviposition stimulatory effect of the extract. Application of the GS, allyl-GS, and benzyl-GS also stimulated oviposition by H. undalis. Significantly more eggs were laid on leaves treated with the aromatic GS, benzyl-GS, than with the alkenyl GS, allyl-GS. Host-plant odor attracted H. undalis females but not males, in behavioral assays conducted in a Y-tube olfactometer. Low concentrations of the GS hydrolysis product, allyl-isothiocyanate, induced anemotaxis of females, but a high concentration of allyl-isothiocyanate was repellent. Oviposition by H. undalis females was not stimulated by host-plant volatiles. Females laid eggs on inserted traps and the walls of the Y-tube regardless of presence or absence of host-plant odor. The relevance of these results in the context of crucifer-insect interactions is discussed. 相似文献
19.
James H. Rea Stephen D. Wratten Richard Sedcole† Peter J. Cameron‡ Stuart I. Davis§ R. Bruce Chapman 《Agricultural and Forest Entomology》2002,4(2):101-107
Abstract
- 1 The use of trap crops to reduce green vegetable bug (GVB) Nezara viridula (L.) (Heteroptera: Pentatomidae) damage to process sweet corn Zea mays (L.) was investigated in three field experiments.
- 2 In the first season, small plots (2.7 m by 10 m) of white mustard Sinapis alba (L.) with pea Pisum sativum (L.) were sown along a crop border and compared with sweet corn alone.
- 3 In the second season, black mustard Brassica nigra (L.) was sown at two sowing dates (14 days apart) and compared with a sweet corn control, to examine how the maturity of the trap crop affected numbers of GVB trapped.
- 4 A field scale experiment was also conducted to determine the effectiveness of black mustard as a trap crop to protect larger areas of sweet corn from GVB.
- 5 In all three experiments, GVB populations were much higher on the trap crops compared with the sweet corn.
- 6 In both small plot experiments, GVB were contained largely within the trap crop for 2 weeks until the sweet corn was harvested.
- 7 The field scale experiment demonstrated the efficacy of the trap cropping technique to protect larger areas of crop from GVB.
- 8 Percentages of damaged sweet corn cobs in the outside row of fields protected by a trap crop were 0% and 1%, respectively, compared with 11% and 22% in control fields.
- 9 Trap cropping is recommended as an effective strategy to manage this insect. Options for cultivating or spraying the trap crops to reduce bug survival are discussed.
20.
Trivalent chromium (Cr3+) is essential for animal and human health, whereas hexavalent Cr (CrO4
2−) is a potent carcinogen and extremely toxic to animals and humans. Thus, the accumulated Cr in food plants may represent
potential health hazards to animals and humans if the element is accumulated in the hexavalent form or in high concentrations.
This study was conducted to determine the extent to which various vegetable crops absorb and accumulate Cr3+ and CrO4
2− into roots and shoots and to ascertain the different chemical forms of Cr in these tissues. Two greenhouse hydroponic experiments
were performed using a recirculating-nutrient culture technique that allowed all plants to be equally supplied with Cr at
all times. In the first experiment, 1 mg L−1 Cr was supplied to 11 vegetable plant species as Cr3+ or CrO4
2−, and the accumulation of Cr in roots and shoots was compared. The crops tested included cabbage (Brassica oleracea L. var. capitata L.), cauliflower (Brassica oleracea L. var. botrytis L.), celery (Apium graveolens L. var. dulce (Mill.) Pers.), chive (Allium schoenoprasum L.), collard (Brassica oleracea L. var. acephala DC.), garden pea (Pisum sativum L.), kale (Brassica oleracea L. var. acephala DC.), lettuce (Lactuca sativa L.), onion (Allium cepa L.), spinach (Spinacia oleracea L.), and strawberry (Fragaria ×
ananassaDuch.). In the second experiment, X-ray absorption spectroscopy (XAS) analysis on Cr in plant tissues was performed in roots
and shoots of various vegetable plants treated with CrO4
2− at either 2 mg Cr L−1 for 7 d or 10 mg Cr L−1 for 2, 4 or 7 d. The crops used in this experiment included beet (Beta vulgaris L. var. crassa (Alef.) J. Helm), broccoli (Brassica oleracea L. var. Italica Plenck), cantaloupe (Cucumis melo L. gp. Cantalupensis), cucumber (Cucumis sativus L.), lettuce, radish (Raphanus sativus L.), spinach, tomato (Lycopersicon lycopersicum (L.) Karsten), and turnip (Brassica rapa L. var. rapifera Bailey). The XAS speciation analysis indicates that CrO4
2− is converted in the root to Cr3+ by all plants tested. Translocation of both Cr forms from roots to shoots was extremely limited and accumulation of Cr by
roots was 100-fold higher than that by shoots, regardless of the Cr species supplied. Highest Cr concentrations were detected
in members of the Brassicaceae family such as cauliflower, kale, and cabbage. Based on our observations and previous findings
by other researchers, a hypothesis for the differential accumulation and identical translocation patterns of the two Cr ions
is proposed.
Received: 27 February 1998 / Accepted: 2 April 1998 相似文献