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1.
Echinochloa crus‐galli (L.) Beauv. var. formosensis Ohwi (2n = 6x = 54, AABBCC genomes) and Echinochloa oryzicola (Vasinger) Vasinger (2n = 4x = 36, AABB) are major paddy weeds in East and Southeast Asia. E. oryzicola has been generally considered to be a paternal genome donor of E. crus‐galli s. l., which includes E. crus‐galli var. formosensis based on cpDNA sequences. Thus, molecular characterization using polymerase chain reaction‐restriction fragment length polymorphism analysis of cpDNA has been proposed as a reliable method for discriminating between the two species. In this study, we report that four accessions of E. crus‐galli var. formosensis from Okinawa, Nagasaki, Shizuoka and Tokyo had similar cpDNA sequences to E. oryzicola and had been misidentified as E. oryzicola using molecular methods. In addition, our results demonstrated that these accessions likely inherited their chloroplast genomes from E. oryzicola and not from an anonymous diploid species during polyploidization. Our findings provide new insights into the evolution of E. crus‐galli s. l. and suggest that identification using the cpDNA molecular method alone is not an appropriate approach to differentiate E. crus‐galli var. formosensis and E. oryzicola.  相似文献   

2.
Laboratory experiments were conducted to analyze the iron (Fe) tolerance of paddy weeds and rice varieties (Oryza sativa) for germination and root elongation. Under a waterlogged soil condition, the Fe(II) content in a soil solution increased with an increase in the ratio of rice straw to the soil. In the presence of 0.9% (w/w) straw to soil, which corresponds approximately to 8 t of straw applied to an area of 1 ha × 10 cm depth in the field, ～80 mg L?1 of Fe(II) was produced in the soil solution. Based on this result, the seeds of rice and the weeds were incubated in a solution with <100 mg L?1 of Fe(II). The presence of 100 mg L?1 of Fe(II) suppressed the germination of Echinochloa crus‐galli var. crus‐galli, Cyperus serotinus, Cyperus difformis, and Monochoria korsakowii. However, it had no effect on the germination of Echinochloa oryzicola, Schoenoplectus juncoides (= Scirpus juncoides var. ohwianus), and Monochoria vaginalis. This level of Fe tolerance was the same as that of rice. These findings suggest that E. oryzicola, S. juncoides, and M. vaginalis can grow under more severe conditions than E. crus‐galli, C. serotinus, C. difformis, and M. korsakowii. In relation to seminal root elongation, the order of tolerance of Fe toxicity was O. sativa cv. Dunghan Shali > O. sativa cv. Hoshinoyume > E. oryzicola > M. vaginalis > S. juncoides. Thus, the results show that the tolerance of rice is greater than that of E. oryzicola, which had a comparatively strong tolerance among the weeds examined, and also that there are differences in tolerance among the rice varieties. These findings suggest that the difference in Fe tolerance is involved in weed control systems when organic materials are applied. If this difference is an important factor in the weed control system, Fe‐tolerant rice varieties, like cv. D. Shali, could facilitate weed control systems due to their higher Fe tolerance ability.  相似文献   

3.
Barnyardgrass, hexaploid Echinochloa crus‐galli, is considered to arise from the hybridization between tetraploid Echinochloa oryzicola and an unknown diploid species. The genetic relationship between E. crus‐galli and E. oryzicola was examined to investigate the position of E. oryzicola in the evolutionary process of E. crus‐galli, based on the nuclear DNA internal transcribed spacer (ITS) and the chloroplast cpDNA trnT‐L, trnL intron, and trnL‐F regions. New World E. crus‐galli was clearly separated from Eurasian E. crus‐galli and showed a close relationship to the American taxa, Echinochloa crus‐pavonis and Echinochloa walteri, in both the ITS and chloroplast DNA. The nrDNA ITS sequences indicated no differentiation between the Eurasian E. crus‐galli and E. oryzicola, in contrast to their clear divergence in the cpDNA sequence. The present results suggest that E. oryzicola is the male donor of E. crus‐galli.  相似文献   

4.
About 400 weed species of 73 families have been reported to occur in upland and lowland rice fields in Vietnam. Two important families are Poaceae and Cyperaceae having 42% of weed species with 21% each. The barnyardgrass, Echinochloa crus‐galli (L.) Beauv., is the most important weed in both transplanted and direct‐seeded rice in this country. The competi‐tion of 25 barnyardgrass plants/m2 causes approximately 50% yield loss. Red sprangletop, Leptochloa chinensis (L.) Nees., is an emerging major weed in direct‐seeded rice. Weedy rice (Oryza sativa L.) was detected in 1994 and is now a new dangerous pest in rice fields. The main reasons are: herbicides which can kill weedy rice completely are not available in the market, non‐chemical methods are laborious and costly, and weedy rice can develop a new generation from contaminated seeds through rice sowing or emerging from soil seed bank. Research results on the Vietnamese situation of barnyardgrass, red sprangletop and weedy rice in terms of biology and management by chemical and non‐chemical methods have been reviewed in this paper.  相似文献   

5.
The effects of herbicide dose on rice‐weed competition were investigated to develop a combined model, which can be utilised to estimate an optimum herbicide dose for a given weed density in paddy rice cultivation. Field studies were conducted in Suwon for rice‐Echinochloa crus‐galli competition and Iksan for rice‐Eleocharis kuroguwai during 2007. The competitive effect of the weeds E. crus‐galli and E. kuroguwai decreased with increasing doses of flucetosulfuron and azimsulfuron, respectively, in the same manner as the standard dose–response curve. The combination of the rectangular hyperbolic model and the standard dose–response curve adequately described the complex effects of herbicide dose and weed competition on rice yield. Parameter estimates were used with the model to predict rice yield and estimate the doses of flucetosulfuron and azimsulfuron required to restrict rice yield loss caused by E. crus‐galli and E. kuroguwai, respectively, to an acceptable level. For a rice yield of 5.0 t ha?1, the model recommended flucetosulfuron doses of 8.7, 13.4 and 20.1 g a.i. ha?1 when infested with E. crus‐galli at 12, 24 and 48 plants m?2 respectively. For a rice yield of 5.2 t ha?1, the model recommended azimsulfuron doses of 3.9, 7.5 and 12.6 g a.i. ha?1 when infested with E. kuroguwai at 24, 48 and 96 plants m?2 respectively. The theoretical outputs of the combined model appear robust and indicate there are opportunities for reduced herbicide use in the field. These now require evaluation under field conditions.  相似文献   

6.
Two major weeds in rice in the Philippines, Sphenochlea zeylanica Gaertn. and Echinochloa crus‐galli (L.) Beauv., are controlled with chemical and cultural methods. In the 1980s, after >10 years of continuous use of 2,4‐D, S. zeylanica evolved resistance to the chemical in those rice fields that had been treated with 2,4‐D once or twice every cropping season. In the 1990s, E. crus‐galli evolved resistance to butachlor and propanil in rice monocrop areas where both herbicides were used continuously for 7–9 years. Rice farmers continue to use 2,4‐D, butachlor and propanil extensively and are often unaware of herbicide resistance or the potential for cross‐resistance, its causes or its implications. In order to control herbicide‐resistant E. crus‐galli, farmers are shifting to locally available herbicides with different modes of action, such as bispyribac, an acetolactate synthase inhibitor, and cyhalofop, an acetyl coenzyme A carboxylase inhibitor. Follow‐up manual weeding or rotary weeding after herbicide spraying, a common farmers’ practice, removes the susceptible and resistant biotypes and could help to delay or prevent the evolution of resistance. Although the resistance mechanisms of both weeds are not determined yet, they could be related to enhanced degradation that is similar to the mechanisms that are shown by the resistant biotypes in other countries.  相似文献   

7.
Abstract

Two morphological variants of Echinochloa crus‐galli were collected from rice fields of an area in Greece where rice has been grown for over a decade and growers have recently been complaining about reduced effectiveness of propanil. Seedling response of the two variants to propanil was compared with that of E. crus‐galli collected from vegetable fields in another area where rice has never been grown. Initial contact toxicity of propanil was similar in all collections. Growth inhibition thereafter was clearly different, resulting in death of the E. crus‐galli from vegetables but not of the E. crus‐galli from rice. The latter could overcome initial toxicity and resume growth at 8 kg/ha of propanil, whereas the former was killed at 2–4 kg/ha. Prevalence of E. crus‐galli forms of higher tolerance resulting from selection through rice husbandry and/or repeated use of propanil may account for the reduced effectiveness of propanil in the area of intensive rice growing.  相似文献   

8.
J Y Li  X K Guo  Q Zhang  C H Liu  Z H Lin  Z M Yu  H Wu  H B He 《Weed Research》2015,55(5):441-448
Screening crop accessions for allelopathic activity is of paramount importance for crop allelopathy research. Previous bioassays often did not use a mixed culture of donor and target plants, did not use soil and were not conducted under natural conditions. In this study, we designed an inhibitory‐circle method in which a rice accession (donor plant) and Echinochloa crus‐galli (target plant) were cultured together in paddy soil under natural conditions. First, we determined that the highest allelopathic activity of allelopathic rice accession PI312777 was at the 5‐leaf stage, and the suitable distance of rice seedlings and E. crus‐galli was 12 cm apart. This method was then validated by a field test. A further 40 rice accessions were evaluated for allelopathic activity to E. crus‐galli using this method. Two rice accessions, PI312777 and Taichung Native 1, had highly allelopathic activity to E. crus‐galli (inhibitory rate > 50%), while another accession, Lemont, had non‐allelopathic activity. These experimental results were in accordance with previous studies using direct field experiments. The inhibitory‐circle method integrated three necessary conditions, that is donor and target plants grown together, with soil as the medium and under natural conditions for reliable results. The ‘inhibitory‐circle method’, which combined donor and target plants, soil medium and field conditions, can give reliable results in one step, compared with laboratory screening methods. Also, the ‘inhibitory‐circle method’ gave results in 30‐35 days, thereby substantially reducing the requirements for time, labour and cost.  相似文献   

9.
The genus Echinochloa (Poaceae) includes numerous problematic weeds over a wide range of ecoregions in the world. To date, molecular markers for species identification and assessing phylogenetic relationship are still limited in the genus Echinochloa. In this study, we developed seven chloroplast molecular markers based on divergent chloroplast regions of E. crus‐galli and E. oryzicola. Furthermore, Marker #1 (psbA) was examined in more than 200 Echinochloa accessions and a phylogenetic tree grouped these Echinochloa accessions into four clades. Additionally, two different E. crus‐galli varieties (E. crus‐galli var. crus‐galli, E. crus‐galli var. praticola) and E. colona were successfully distinguished by this marker. The developed molecular markers contribute to better identification of Echinochloa taxa.  相似文献   

10.
Gene expression was compared under favorable germination conditions between dormant and non-dormant seeds of rice paddy Echinochloa weeds and a domesticated Echinochloa species lacking dormancy. Two dormancy-specific cDNAs, Ecd1 and Ecd2 , were identified by differential display. Northern blot analysis revealed that these genes were more strongly expressed in dormant seeds than in non-dormant seeds. A database search for the Ecd1 sequence revealed no significant homology with any known proteins, but the Ecd2 sequence was highly homologous with the α-chain of mitochondrial H+-transporting adenosine triphosphate (ATP) synthase in rice ( Oryza sativa L.). These findings indicate that the gene encoding the enzyme associated with conventional aerobic respiration is more abundantly transcribed in dormant seeds. The results reported in the present study suggest that dormant seeds of paddy Echinochloa weeds, which appear during the period when paddy soil becomes aerobic by drainage, may maintain viability primarily by efficient conventional aerobic respiration, including ATP synthesis catalyzed by the mitochondrial H+-transporting ATP synthase.  相似文献   

11.
BACKGROUND: Fifteen novel derivatives of D‐DIBOA, including aromatic ring modifications and the addition of side chains in positions C‐2 and N‐4, had previously been synthesised and their phytotoxicity on standard target species (STS) evaluated. This strategy combined steric, electronic, solubility and lipophilicity requirements to achieve the maximum phytotoxic activity. An evaluation of the bioactivity of these compounds on the systems Oryza sativa–Echinochloa crus‐galli and Triticum aestivum–Avena fatua is reported here. RESULTS: All compounds showed inhibition profiles on the two species Echinochloa crus‐galli (L.) Beauv. and Avena fatua L. The most marked effects were caused by 6F‐4Pr‐D‐DIBOA, 6F‐4Val‐D‐DIBOA, 6Cl‐4Pr‐D‐DIBOA and 6Cl‐4Val‐D‐DIBOA. The IC50 values for the systems Echinochloa crus‐galli–Oryza sativa and Avena fatua–Triticum aestivum for all compounds were compared. The compound that showed the greatest selectivity for the system Echinochloa crus‐galli–Oryza sativa was 8Cl‐4Pr‐D‐DIBOA, which was 15 times more selective than the commercial herbicide propanil (Cotanil‐35). With regard to the system Avena fatua–Triticum aestivum, the compounds that showed the highest selectivities were 8Cl‐4Val‐D‐DIBOA and 6F‐4Pr‐D‐DIBOA. The results obtained for 6F‐4Pr‐D‐DIBOA are of great interest because of the high phytotoxicity to Avena fatua (IC50 = 6 µM , r2 = 0.9616). CONCLUSION: The in vitro phytotoxicity profiles and selectivities shown by the compounds described here make them candidates for higher‐level studies. 8Cl‐4Pr‐D‐DIBOA for the system Echinochloa crus‐galli‐Oryza sativa and 6F‐4Pr‐D‐DIBOA for Avena fatua‐Triticum aestivum were the most interesting compounds. Copyright © 2010 Society of Chemical Industry  相似文献   

12.
Echinochloa species are amongst the most problematic weeds in rice fields of Korea. The steady reliance on the Acetyl‐CoA carboxylase (ACCase) and acetolactate synthase inhibiting herbicides for control of these weeds has led to resistance to these herbicides. The objective of this study was to assess the genetic diversity among populations of ACCase inhibitor‐resistant and ‐susceptible Echinochloa crus‐galli and E. oryzicola in Korea, to better understand their population structure and possible origins of resistance. Seven simple sequence repeat markers were applied to assess the genetic diversity between resistant and susceptible E. crus‐galli and E. oryzicola from 12 populations in Korea. Genetic diversity was slightly higher in the resistant group. The Unweighted Pair Group Method using Arithmetic algorithm (UPGMA) dendrogram generated two distinct clades. One clade consisted of Echinochloa spp. from three populations, i.e. Anmyeondo, Gimje 4 and Gongju, which are resistant and differentiated from the susceptible populations, and the other clade contained the rest of the populations. Structure modelling supported two clades of UPGMA clustering. Based on these data, we can infer that some resistant populations are greatly differentiated, whereas other resistant biotypes are still building up resistance in rice fields in Korea. Resistance traits will be fixed and continue to spread over time without proper control measures.  相似文献   

13.
This study was conducted to evaluate the cross‐resistance of acetolactate synthase (ALS) inhibitors with different chemistries, specifically azimsulfuron (sulfonylurea), penoxsulam (triazolopyrimidine sulfonanilide) and bispyribac‐sodium (pyrimidinyl thio benzoate), in Echinochloa oryzicola and Echinochloa crus‐galli that had been collected in South Korea and to investigate their herbicide resistance mechanism. Both Echinochloa spp. showed cross‐resistance to the ALS inhibitors belonging to the above three different chemistries. In a whole plant assay with herbicides alone, the resistant/susceptible ratios for azimsulfuron, penoxsulam and bispyribac‐sodium were 12.6, 28.1 and 1.9 in E. oryzicola and 21.1, 13.7 and 1.8 in E. crus‐galli, respectively. An in vitro ALS enzyme assay with herbicides showed that the I 50‐values of the resistant accessions were approximately two‐to‐three times higher than the susceptible accessions, with no statistical difference, suggesting that the difference in ALS sensitivity cannot explain ALS inhibitor resistance in Echinochloa spp. for azimsulfuron, penoxsulam and bispyribac‐sodium. A whole plant assay with fenitrothion showed that the GR 50‐values significantly decreased in both the resistant E. oryzicola and E. crus‐galli accessions when azimsulfuron, penoxsulam and bispyribac‐sodium were applied with the P450 inhibitor, while no significant decrease was observed in the susceptible accessions when the P450 inhibitor was used. Thus, these results suggest that ALS inhibitor cross‐resistance for azimsulfuron, penoxsulam and bispyribac‐sodium is related to enhanced herbicide metabolism.  相似文献   

14.
Investigations were conducted during the 2003, 2004 and 2005 growing seasons in northern Greece to evaluate effects of tillage regime (mouldboard plough, chisel plough and rotary tiller), cropping sequence (continuous cotton, cotton–sugar beet rotation and continuous tobacco) and herbicide treatment on weed seedbank dynamics. Amaranthus spp. and Portulaca oleracea were the most abundant species, ranging from 76% to 89% of total weed seeds found in 0–15 and 15–30 cm soil depths during the 3 years. With the mouldboard plough, 48% and 52% of the weed seedbank was found in the 0–15 and 15–30 cm soil horizons, while approximately 60% was concentrated in the upper 15 cm soil horizon for chisel plough and rotary tillage. Mouldboard ploughing significantly buried more Echinochloa crus‐galli seeds in the 15–30 cm soil horizon compared with the other tillage regimes. Total seedbank (0–30 cm) of P. oleracea was significantly reduced in cotton–sugar beet rotation compared with cotton and tobacco monocultures, while the opposite occurred for E. crus‐galli. Total seed densities of most annual broad‐leaved weed species (Amaranthus spp., P. oleracea, Solanum nigrum) and E. crus‐galli were lower in herbicide treated than in untreated plots. The results suggest that in light textured soils, conventional tillage with herbicide use gradually reduces seed density of small seeded weed species in the top 15 cm over several years. In contrast, crop rotation with the early established sugar beet favours spring‐germinating grass weed species, but also prevents establishment of summer‐germinating weed species by the early developing crop canopy.  相似文献   

15.
This study aimed to identify the potential allelopathic indigenous rice (Oryza sativa L. ssp. indica) varieties from Bangladesh using a performance study in a weed‐infested field and to assess the extent of allelopathic interference relative to resource competition in a glasshouse experiment. Six varieties – namely, “Boterswar,” “Goria,” “Biron” and “Kartiksail” as the most allelopathic, “Hashikolmi” as weakly allelopathic and “Holoi” as nonallelopathic – were raised following a nonweed control method. The infestation levels of weed species were calculated using Simpson's Diversity Index (SDI), which ranged from 0.2 to 0.56. However, a significant correlation coefficient (0.87, P < 0.001) was obtained from these field data compared with the root inhibition percentage from the laboratory bioassay, and the “Boterswar” variety was the most allelopathic. The interactions between the allelopathic variety “Boterswar,” weakly allelopathic variety “Hashikolmi” and Echinochloa oryzicola via a target (rice)‐adjacent (E. oryzicola) cogrowth culture were determined in a hydroponic arrangement. The relative competitive intensity (RCI) and the relative neighbor effect (RNE) values showed that the crop–weed interaction was facilitation for “Boterswar” and competition for “Hashikolmi” and E. oryzicola in rice/E. oryzicola cogrowth cultures. The allelopathic effects of “Boterswar” were much higher than the resource competition in rice/E. oryzicola cogrowth cultures. The converse was observed for “Hashikolmi.” Moreover, the mineral content of E. oryzicola was severely affected by “Boterswar”/E. oryzicola cogrowth cultures’ exudate solution. Therefore, the allelopathic potential of “Boterswar” variety might be useful for developing the weed‐suppressing capacity of rice, which will likely have a significant influence on paddy weed control.  相似文献   

16.
G Li  S G Wu  R X Yu  T Cang  L P Chen  X P Zhao  L M Cai  C X Wu 《Weed Research》2013,53(5):314-321
Plant glutathione S‐transferase (GST) forms a major part of the herbicide detoxification enzyme network in plants. A GST cDNA was isolated from Echinochloa crus‐galli and characterised. The gene, designated EcGST1 (E. crus‐galli GeneBank no: JX518596 ), has a 684 bp open reading frame predicted to encode a 25 kD protein. Sequence alignment showed that EcGST1 is a GST homologue. Its expression in response to quinclorac treatment was monitored in seedlings (leaves and roots) and adult plants (leaves, roots, stems and seeds) of quinclorac‐resistant (R) and susceptible (S) biotypes of E. crus‐galli. EcGST1 expression was 1.5–3 times greater in the R plants than in the S plants. However, after exposure to quinclorac, the difference in the expression levels of EcGST1 in R plants, compared with S plants, increased to a ratio of 6–10. Enhanced EcGST1 levels should enable greater quinclorac detoxification following quinclorac stimulation in R plants. GST‐based metabolism may be partially responsible for resistance to quinclorac in E. crus‐galli. The results suggest a new resistance mechanism for this R biotype in Chinese rice fields.  相似文献   

17.
Field experiments were conducted in northern Greece in 2003 and 2004 to evaluate effects of tillage regimes (moldboard plowing, chisel plowing, and rotary tilling), cropping sequences (continuous cotton, cotton‐sugar beet rotation, and continuous tobacco) and herbicide treatments with inter‐row hand hoeing on weed population densities. Total weed densities were not affected by tillage treatment except that of barnyardgrass (Echinochloa crus‐galli), which increased only in moldboard plowing treated plots during 2003. Redroot pigweed (Amaranthus retroflexus) and black nightshade (Solanum nigrum) densities were reduced in continuous cotton, while purple nutsedge (Cyperus rotundus), E. crus‐galli, S. nigrum, and johnsongrass (Sorghum halepense) densities were reduced in tobacco. A. retroflexus and S. nigrum were effectively controlled by all herbicide treatments with inter‐row hand hoeing, whereas E. crus‐galli was effectively reduced by herbicides applied to cotton and tobacco. S. halepense density reduction was a result of herbicide applied to tobacco with inter‐row hand hoeing. Yield of all crops was higher under moldboard plowing and herbicide treatments. Pre‐sowing and pre‐emergence herbicide treatments in cotton and pre‐transplant in tobacco integrated with inter‐row cultivation resulted in efficient control of annual weed species and good crop yields. These observations are of practical relevance to crop selection by farmers in order to maintain weed populations at economically acceptable densities through the integration of various planting dates, sustainable herbicide use and inter‐row cultivation; tools of great importance in integrated weed management systems.  相似文献   

18.
The effects of the planting method (transplanting vs. direct seeding), rice cultivar (Sen Pidao vs. Phka Rumduol), and herbicide application (admixture of bentazone and cyhalofop‐butyl) on weeds and weed seed banks were quantified in unflooded, shallowly flooded, and deeply flooded paddy fields in Cambodia in 2005 and 2006. Broad‐leaved weeds infested more toward maturity in 2006 than in 2005, particularly in directly seeded plots. Weed dry weights at pre‐heading and/or maturity were consistently reduced by herbicide application and Phka Rumduol cultivar, while weed numbers increased under unflooded condition. The proportion of sedges was consistently larger in directly seeded and non‐herbicide plots at pre‐heading. Larger numbers and dry weights of sedges and total weeds in 2005 caused larger seed bank sizes of sedges and total weeds in 2006, which further caused their infestation in 2006. A greater weed dry weight at 62 days after sowing in 2005 resulted in larger seed banks of Cyperus iria and Fimbristylis miliacea, which were most severe under non‐herbicide, direct‐seeded treatment, while that at rice maturity resulted in larger seed banks of Cyperus difformis, Scirpus juncoides, and Lindernia antipoda. Overall, sedges shared the majority of the total weed seed bank, followed by broad‐leaved weeds and then grasses. A lower yield in 2005 led to significantly larger seed bank sizes of sedges, but not of grasses or broad‐leaved weeds. Rice yield reduction was consistently related to larger numbers of sedges by heading and those of grasses at maturity.  相似文献   

19.
Echinochloa crus‐galli is a serious weed worldwide. Microsatellite markers (simple sequence repeats, SSRs) are important molecular markers that are used widely for studying genetic diversity in plants. However, a limited number of SSRs is available for E. crus‐galli. The restriction site‐associated DNA (RAD) sequencing approach was combined with Illumina DNA sequencing for the rapid and mass detection of SSRs in E. crus‐galli. The RAD tags were generated from the genomic DNA of E. crus‐galli and were sequenced in order to produce 6921.6 Mb of high‐quality sequences with 45.1% guanine–cytosine content. In total, 3081 putative SSRs were detected, of which 82.2% were dinucleotide motif‐repeats. AT was the most frequent motif, accounting for 35.0% of the SSRs. In order to test the validity of the SSRs that were developed here, eight SSRs that were selected from putative SSRs were used to study the genetic diversity and structures of 20 E. crus‐galli populations that had been collected from rice fields in eastern China. Ninety‐seven alleles were amplified from the eight microsatellite loci among the 20 E. crus‐galli populations. These populations showed low genetic diversity and were classified on the basis of their genetic structures into three distinct groups that corresponded to the three regions of population sampling. The SSRs that were identified in this study represent a valuable resource for studying the genetic diversity, population biology and evolution of E. crus‐galli.  相似文献   

20.
Evaluation of rice allelopathy in hydroponics   总被引：3，自引：0，他引：3  
The inhibitory activity of water extracts from the shoots and roots of three rice cultivars, Taichung native 1 (TN1) and IAC165 (both allelopathic rice) and AUS196 (non-allelopathic rice), grown in hydroponics was evaluated. The release of germination inhibitors by allelopathic rice plants into hydroponic solution was also determined with freshly collected solution and XAD-4 resin desorbate. The degree of the inhibition was quantified in terms of root growth in Echinochloa colona, Echinochloa crus-galli, Echinochloa crus-galli var. oryzicola, Triantema portulacastrum and Lactuca sativa. The allelopathic activity of rice was species specific, and depended on source and concentration. Root length of all test species was inhibited by the different concentrations of shoot extract of allelopathic and non-allelopathic rice. However, of the three cultivars, TN1 showed higher inhibition than IAC165 and AUS196 in all test species. Water extracts of shoots and roots significantly inhibited root growth in E. crus-galli but the shoot extract gave a greater inhibitory effect on E. crus-galli than the root extract. Root exudate of TN1 inhibited root elongation of E. crus-galli from 2 weeks after transplanting (WAT) and the inhibition continued for 4 WAT. The results confirmed the previous finding of a laboratory bioassay that the TN1 had allelopathic activity and produced allelochemicals that inhibit growth of some weed species.  相似文献   

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