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1.
It is becoming apparent that allelopathy plays a significant role in the competitive ability of cereals against weeds; barley, wheat and rice cultivars with high allelopathic activity have been identified. However, direct breeding efforts to improve allelopathy have to date only been reported in rice. In this study, a breeding programme in spring wheat ( Triticum aestivum ) was evaluated to determine the efficiency of selection of allelopathy and the ability of breeding lines to suppress weeds in the field. The material used originated from a cross between a Swedish cultivar with low allelopathic activity and a Tunisian cultivar with high allelopathic activity. Allelopathic activity was measured as growth inhibition of perennial ryegrass ( Lolium perenne ) roots when grown together with the wheat cultivars on agar. For screening of F2 populations, a single plant bioassay was used for the first time. In the F6 and F7 generations, three breeding lines with an average improved allelopathy of 20% and one line with an unimproved allelopathy activity, but with the same phenotype as the high allelopathic lines, were tested together with the low allelopathic Swedish parent. The main result from the field study was a 19% average reduction of weed biomass for the high allelopathic lines, but no significant reduction of the low allelopathic breeding line. Early shoot length and early crop biomass (stages 37–39, Zadoks scale) and straw length of the high allelopathic lines were not significantly different from the Swedish parent. A negative effect was that grain yield was reduced by 9% in the high allelopathic lines. It is suggested that the reduced biomass of weeds in plots planted with the highly allelopathic wheat lines is related to differences in allelopathic activity and not differences in plant growth.  相似文献   

2.
Crop cultivars with allelopathic capability   总被引：12，自引：0，他引：12  
WU  Pratley  Lemerle  & Haig 《Weed Research》1999,39(3):171-180
Allelopathy has potential in integrated weed management. Crop plants have the capability to produce and exude allelochemicals into their surroundings to suppress the growth of weeds in their vicinity. Selection for superior genotypes with allelopathic potential has been carried out in several field crops, and evidence has accumulated that crop cultivars differ significantly in their ability to inhibit the growth of certain weed species. To date, progress has been made in understanding the genetics of crop allelopathic activity, and successful genetic manipulation of this trait has also been demonstrated. However, much more research needs to be carried out in order to have a thorough understanding of the genetic control of allelopathic activity. Several genes might be involved in regulating the production and exudation of allelochemicals. Concerted efforts using advances in plant biotechnology will help to unveil the genetics of this trait. Once the allelopathic genes have been located, a breeding programme could be initiated to transfer the genes into modern cultivars to enhance their allelopathic activity for weed suppression, thereby reducing over-reliance on herbicides.  相似文献   

3.
Allelopathic studies of common wheat (Triticum aestivum L.)   总被引：1，自引：0，他引：1  
Wheat ( Triticum aestivum L.) is a common name for cereal grasses of a genus of the grass family, cultivated for food since prehistoric times by the people of the temperate zones and now the most important grain crop of those regions. It has allelopathic potential if used as a cover crop for weed control in various cropping systems. Research results indicate that, among modern varieties, there is a variable resistance potential against weeds. Numerous allelochemicals have been identified in wheat, mainly belonging to the categories of phenolic acids, hydroxamic acids and short-chain fatty acids. Some researchers conceived that wheat allelopathy is genetically controlled, but systematic research on gene behaviors is lacking. The negative effects of wheat on other crops under different agricultural production systems have been reported. Research is needed to determine the genetic control of wheat allelopathy prior to the development of allelopathic wheat varieties. Further research is needed to conduct in vitro studies to isolate, identify and quantify allelochemicals from living wheat plants at different growth stages. Also, the relationship between heritages of modern varieties and the allelopathic characteristics of wheat during their evolution and selection by humans is still unclear. There is also a lack of research on the modern varieties as to whether the allelopathic potential can be genetically transferred to the next generation. In the future, more models and assessment systems must be developed to illuminate the essence of allelopathy and the genomes of wheat with allelopathic traits should be constructed to make available allelopathic bioinformation on wheat.  相似文献   

4.
水稻化感物质的代谢途径及基因调控   总被引：3，自引：0，他引：3  
水稻化感作用和竞争作用是水稻抑草的两个方面,化感作用是通过水稻植株向环境中释放化感物质实现对杂草的生长抑制作用。水稻化感作用的物质主要有4大类:酚类、萜类、含氮化合物和其他化感物质。水稻酚类化感物质的代谢物质为莽草酸和乙酸-丙二酸;类萜是由乙酰CoA经甲羟戊酸和异戊二烯焦磷酸(IPP)转化而来的,类萜生物合成中起作用的是IPP;含氮化感物质是由不同的氯基酸衍生来的。很多植物次生物质产生的酶基因已得到了克隆。紫外光处理水稻化感材料后12 h和24 h,被诱导的苯丙氨酸氨基裂合酶(PAL)、肉桂酸-4-羟化酶(CA4H)和二萜环化酶的酶活力比紫外光处理的无化感作用水稻中的要高2-4倍。用胁迫相关酶的编码基因对水稻的化感作用进行基因调控研究是探明产生水稻化感物质基因的重要策略。  相似文献   

5.
The effects of cover crops on weeds and the underlying mechanisms of competition, physical control and allelopathy are not fully understood. Current knowledge reveals great potential for using cover crops as a preventive method in integrated weed management. Cover crops are able to suppress 70–95% of weeds and volunteer crops in the fall‐to‐spring period between two main crops. In addition, cover crop residues can reduce weed emergence during early development of the following cash crop by presenting a physical barrier and releasing allelopathic compounds into the soil solution. Therefore, cover crops can partly replace the weed suppressive function of stubble‐tillage operations and non‐selective chemical weed control in the fall‐to‐spring season. This review describes methods to quantify the competitive and allelopathic effects of cover crops. Insight obtained through such analysis is useful for mixing competitive and allelopathic cover crop species with maximal total weed suppression ability. It seems that cover crops produce and release more allelochemicals when plants are exposed to stress or physical damage. Avena strigose, for example, showed stronger weed suppression under dry conditions than during a moist autumn. These findings raise the question of whether allelopathy can be induced artificially. © 2019 Society of Chemical Industry  相似文献   

6.
Allelopathy is a naturally occurring ecological phenomenon of interference among organisms that may be employed for managing weeds, insect pests and diseases in field crops. In field crops, allelopathy can be used following rotation, using cover crops, mulching and plant extracts for natural pest management. Application of allelopathic plant extracts can effectively control weeds and insect pests. However, mixtures of allelopathic water extracts are more effective than the application of single-plant extract in this regard. Combined application of allelopathic extract and reduced herbicide dose (up to half the standard dose) give as much weed control as the standard herbicide dose in several field crops. Lower doses of herbicides may help to reduce the development of herbicide resistance in weed ecotypes. Allelopathy thus offers an attractive environmentally friendly alternative to pesticides in agricultural pest management. In this review, application of allelopathy for natural pest management, particularly in small-farm intensive agricultural systems, is discussed.  相似文献   

7.
An improvement in the allelopathic potential of rice will have a great impact on both low‐input and high‐input management systems. Allelopathy alone is not likely to replace other weed control practices, but it surely functions as a component of integrated weed management technology. Allеlораthу is thе рrосе?? whеrеbу аn organic сhеm?саl (аllеlосhеm?саl) that is rеlеа?еd from one рlаnt influences the growth and dеvеlорmеnt of other plants. Allelochemical biosynthesis, release, environmental fate and action on other plant species can depend on genetic factors or on the environment and their interaction. As a result of these interactions, allelopathy is a complex phenomenon with limited repeatability. The term “allelopathy” has undergone several changes and it has been defined as any direct or indirect harmful or beneficial effect of a plant on another through the production of chemical compounds that it releases into the environment. Rice allelopathy is one of the modes of interaction between receptor and donor plants and could exert either positive effects or negative effects. The development of genetic modification by enhancing crops with allelopathic traits should be done cautiously, given the ecological risk (untoxic and safe for humans and the ecosystem, crop productivity, the ratio of benefit and cost etc.). Finally, this article reviews the agricultural production system allelopathy of novel applications, including the role of allelochemical consortia and their potential use in no‐tillage cropping systems, cover crops or mulches.  相似文献   

8.
The occurrence of herbicide‐resistant weeds has boosted interest in the use of crop allelopathy as a potential alternative to herbicides for weed control in rice (Oryza sativa). The phytotoxic compounds that are released by rice could help to enhance its competitive ability and improve weed management. This study aimed to screen rice genotypes for phytotoxic activity, quantify the amount of momilactone B in various rice tissues, and identify the potential parental lines for quantitative trait locus analysis. Therefore, a total of 41 cultivars from germplasm collections was evaluated for their effects. Significant differences were found among the rice cultivars in their ability to reduce the germination, root growth, and root dry weight accumulation of Alisma plantago‐aquatica. The leaf extract was the most inhibitory to germination. Out of the five cultivars that were tested, momilactone B was detected in four of them: Marateli, Kizilirmak, Karadeniz, and Kiziltan. Karadeniz and Kiziltan were identified as the rice cultivars with a high momilactone B content in the tissues and therefore they could be used in breeding programs to enhance the phytotoxic potential of rice. The development of a rice cultivar with proven allelopathic characteristics could provide an environmentally friendly and low‐cost approach for the control of A. plantago‐aquatica.  相似文献   

9.
BACKGROUND: A number of techniques, including cultural management, allelopathy and bioherbicide, have been considered as alternatives for synthetic herbicides, but successful weed control will require the careful integration of these multiple techniques. This study was conducted to assess the use of allelopathic rice varieties in combination with cultural management options on paddy weeds, in order to develop an allelopathy-based technique to reduce herbicide use in paddies. RESULTS: The weed-suppressive effects of the rice varieties tested varied highly with allelopathic trait, planting pattern and cultural management including planting density, flooding depth and duration and supply of nitrogen. Allelopathic rice varieties PI312777 and Huagan-1 demonstrated much stronger weed suppression than the non-allelopathic variety Huajianxian under the same planting pattern and cultural management. Their weed-suppressive effect was increased with cultural management options. In particular, if integrated cultural management options of allelopathic rice varieties included a low-dose (bensulfuron-methyl, 25 g AI ha(-1), a third of the recommended dose) herbicide application, the emergence and growth of most weeds found in paddy fields was completely controlled. No grain yield reduction for allelopathic varieties occurred under integrated cultural management options, whereas with the non-allelopathic variety a reduction of up to 45-60% was measurable even with the low-dose herbicide application. CONCLUSION: The allelopathic potential of rice varieties will likely have a great impact on paddy weed control if integrated with cultural management options and application of low doses of herbicides. Therefore, it is feasible to reduce herbicide input in paddies if allelopathic rice is grown under integrated cultural management practices.  相似文献   

10.
The interference of allelopathic weeds with crop plants might be mediated by volatile allelochemicals. In this study, the essential oil constituents of two weeds, wild oat (Avena fatua) and crabgrass (Digitaria sanguinalis), were investigated in relation to their effects on the growth and allelochemical production of wheat (Triticum aestivum). Subsequently, by means of gas chromatography and gas chromatography‐mass spectrometry, 52 compounds were identified from the crabgrass essential oil, particularly a signaling compound called methyl jasmonate, while 28 constituents were detected in the wild oat essential oil. Both essential oils were rich in terpenoids and inhibited the growth of wheat in air, filter paper and soil media but their inhibition varied with the growth medium and the weed species. In both the air and the filter paper media, there were not significant differences in the dry weight of wheat between the wild oat and the crabgrass essential oils. However, there was a greater reduction in the dry weight of the wheat root and plant with the wild oat essential oil than with the crabgrass essential oil in the soil medium. Furthermore, the production of the allelochemical, 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one, in wheat was induced by the essential oils. The results suggest that allelopathic interference with wheat by wild oat and crabgrass affects not only the biomass allocation, but also the allelochemical production, of wheat.  相似文献   

11.

Background

Selecting wheat varieties with allelopathic potential or high competitiveness against weeds is a sustainable solution for organic farming to eliminate the use of synthetic herbicides. Wheat is one of the most economically important crops. This study focuses on screening the allelopathic or competitive potential of four wheat cultivars, Maurizio, NS 40S, Adesso and Element, on two weeds of interest due to acquired herbicide resistance, Portulaca oleracea and Lolium rigidum, through germination and growth bioassays and the identification and quantification of benzoxazinoids (BXZs) and polyphenols (phenolic acids and flavonoids).

Results

The different cultivars showed different abilities to manage surrounding weeds and different capacity to exude or accumulate specialized metabolites in the presence of those weeds. Furthermore, each cultivar behaved differently depending on the weed present in the medium. The most efficient cultivar to control the tested monocot and dicot weeds was Maurizio, as it effectively controlled germination and growth of L. rigidum and P. oleracea while exuding large amounts of benzoxazinones through the roots, especially the hydroxamic acids 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one and dihydroxy-2H-1,4-benzoxaxin-3(4H)-one. By contrast, NS 40S, Adesso and Element showed the potential to control the growth of just one of the two weeds through allelopathy or competition.

Conclusion

This study reveals that Maurizio is the most promising wheat cultivar for sustainable weed control, and that the screening of crop varieties with allelopathic potential, which results in the displacement of synthetic herbicides, is an immediate solution in ecological and sustainable agriculture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

12.
A range of 111 rice cultivars was studied for weed-suppressing ability in field experiments with a sown infestation of Echinochloa crus-galli. Cultivars differed significantly in their ability to suppress the growth of E. crus-galli , and the differences were reasonably reproducible over three seasons. The same rice cultivars were tested in a laboratory screening for allelopathic potential, which showed significant differences in the ability to reduce root growth of E. crus-galli . Correlation between the laboratory screening and the field experiments showed that field performance could be described to some extent by E. crus-galli root length reduction in the laboratory. Plant height in the field experiment was correlated with weed biomass 8 weeks after seeding. Even among the most weed-suppressing rice cultivars, however, all heights were represented. None of the measured growth parameters from greenhouse studies could explain the distribution of weed-suppressing rice cultivars. This indicates that allelopathy in combination with competitive ability determines the weed interference outcome of a given rice cultivar.  相似文献   

13.
Barley (Hordeum vulgare L.) landraces and cultivars from Finland, Sweden, Denmark and the Baltic states, in total 127, were analysed for allelopathic activity against ryegrass (Lolium perenne L.). The germplasm covered most of the gene pool used during 100 years of barley breeding. An agar‐based bioassay developed for screening allelopathic activity was used. In the germplasm from all countries a decreasing trend in allelopathic activity was observed with the introduction of new cultivars from 14% for the Swedish to 31% for the Finnish cultivars. In the Finnish, Swedish and Baltic cultivars an increase in root growth was noticed, and changes in root biomass therefore cannot explain the decrease in allelopathy. In fact, the allelopathic activity per milligram root decreased with 32–85%. In contrast, root growth decreased over time in the Danish collection. In the Finnish cultivars both two‐ and six‐row barley cultivars were tested with similar results. Allelopathic activity of barley probably originated from different landraces, and in most cases from a specific landrace from the Swedish island of Gotland. We suspect that more than 100 years of selection and breeding have resulted in a dilution of the genes from landraces and consequently a declining allelopathic activity. In the Swedish collection, two cultivars did not follow the general trend and in both cultivars, several landraces had been combined.  相似文献   

14.
The objectives of this study were to identify traits in spring barley (Hordeum vulgare) and spring wheat (Triticum aestivum) related to the competitive ability of the crop and to determine their importance. Weed biomass 1–2 weeks prior to ear emergence was used as a measure of genotypic differences in competitiveness against weeds. Crop trait measurements comprised early crop biomass, early shoot height, straw length, heading and maturity. Early crop biomass 1–2 weeks prior to ear emergence was used as an overall trait for the various characters related to early vigour. In addition to these morphological traits, the potential allelopathic activity of the tested cultivars was determined using an agar-based bioassay with Lolium perenne (ryegrass). In both barley and wheat, multiple regression analysis revealed that early crop biomass and potential allelopathic activity were the only parameters that significantly contributed to competitiveness. In barley, early crop biomass explained 24–57% of the observed genotypic variance across 4 years, allelopathic activity explained 7–58% and combined they explained 44–69% of the observed genotypic variance. In wheat, the corresponding figures were lower: 14–21% for early biomass, 0–21% for allelopathic activity and 27–37% when combined. Model predictions suggested that new cultivars with increased early vigour and allelopathic activity offer a potential to further reduce weed interference.  相似文献   

15.
Wheat is an important cereal food crop providing key nutrients to humankind. Rusts are the most destructive pathogens of cereal crops, with the exception of rice, across the world and resistant cultivars have been widely employed to reduce the yield losses caused by them. The modern intensive monoculture of cultivars and changing climatic conditions has created congenial conditions for the emergence of new virulent races such as Ug99, which is a great concern for world food security. Conventional breeding efforts have not been effective in quickly developing new varieties with durable and broad‐spectrum resistance against the rapidly evolving rust pathogen races. However, in the last two decades, biotechnological methods such as marker‐assisted selection (MAS) and transgenic technology have provided novel strategies for enhancing resistance levels and durability in crop plants in a short span of time. Nevertheless, broad application of transgenics in agriculture is hindered by biosafety apprehensions. In recent years, improved versions of biotechnological breeding methods such as genomic selection, genome editing technologies, cisgenesis and intragenesis, RNA‐dependent DNA methylation (RdDM), agroinfiltration and reverse breeding are gaining popularity. These technologies provide a tremendous capability to manipulate crop plants more precisely than before and accelerate crop improvement efforts for sustained food production as well as overcoming safety concerns associated with food crops.  相似文献   

16.
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   

17.
Current status of biological control of paddy weeds in Vietnam   总被引：1，自引：0，他引：1  
Rice is a staple food in Vietnam and accounts for > 7.7 × 106 cultivated ha, which provide 35.5 × 106 t of rice, of which 4.2 × 106 t were exported in 2004. The enlargement of the cropping area and the enhancement of rice yield have rapidly increased the amount of agrochemicals, including herbicides, in crop production in Vietnam. From 1990–2003, the percentage of herbicides in total pesticides has increased ≈ 10-fold to 30.2%. In addition, the improper use of herbicides caused environmental hazards, unsafe agricultural products, and human health problems. Biological management integrated with traditional weed control techniques might help to reduce the dependence on synthetic herbicides and build eco-friendly, sustainable agricultural production in Vietnam. This paper reviews the efforts in establishing a strategy for biological management of weeds that was conducted in recent years by Vietnamese weed scientists. This has included cropping system management, water and soil management, integrated pest management, and utilization of plant allelopathy as major components of the strategy. Many plants with strong allelopathic potential can be a source for biological weed suppression and soil fertility improvement. The utilization of allelopathic properties in rice might also help to provide new rice cultivars with weed-suppressing characteristics.  相似文献   

18.
Allelopathy studies the interactions among plants, fungi, algae and bacteria with the organisms living in a certain ecosystem, interactions that are mediated by the secondary metabolites produced and exuded into the environment. Consequently, allelopathy is a multidisciplinary science where ecologists, chemists, soil scientists, agronomists, biologists, plant physiologists and molecular biologists offer their skills to give an overall view of the complex interactions occurring in a certain ecosystem. As a result of these studies, applications in weed and pest management are expected in such different fields as development of new agrochemicals, cultural methods, developing of allelopathic crops with increased weed resistance, etc. The present paper will focus on the chemical aspects of allelopathy, pointing out the most recent advances in the chemicals disclosed, their mode of action and their fate in the ecosystem. Also, attention will be paid to achievements in genomics and proteomics, two emerging fields in allelopathy. Rather than being exhaustive, this paper is intended to reflect a critical vision of the current state of allelopathy and to point to future lines of research where in the authors' opinion the main advances and applications could and should be expected.  相似文献   

19.
Cover crops have been shown to be important integrated weed management tools. In addition to directly competing with weeds, cover crops can provide weed suppressive effects following incorporation through release of allelopathic compounds and/or changes to nutrient availability. Incorporation of a cover crop mixture may provide a synergistic or antagonistic effect on weed suppression by further altering nutrient dynamics. To investigate this phenomenon, we evaluated the suppressive effects following incorporation of annual ryegrass, buckwheat, brown mustard, and phacelia sown with and without field pea on germination and growth of several pernicious weed species. Further, we used the additive partitioning model to determine if pea synergistically improved biomass production and weed suppression of cover crops. Our results demonstrate that following incorporation, cover crop residues suppress weed germination and weed biomass production. According to the additive partitioning model, the addition of pea had an antagonistic effect on buckwheat and brown mustard biomass production and decreased buckwheat weed suppression by 8%. In contrast, the addition of field pea greatly enhanced biomass production of phacelia at a reduced seeding rate suggesting a positive biodiversity effect. Limited evidence was found for changes to nutrient availability following cover crop incorporation, however, a dose-dependent effect of cover crop residue on weed suppression suggests allelopathy and/or nutrient availability may have a role on weed seed germination success. Together, our results support the use of incorporated cover crop residues as an integrated weed management tool.  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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