ORCID Profile
0000-0003-4690-1309
Current Organisations
Charles Sturt University
,
Charles Sturt University - Wagga Wagga Campus
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/EA02046
Abstract: Sheep and other livestock are capable of ingesting seeds from weeds and desirable pasture species and excreting a percentage of viable seeds. As livestock are used to graze stubble paddocks after harvest, any crop seed shed before harvest or spilt during the harvesting process could also be ingested and subsequently excreted as viable seed. Knowledge of the rate of passage and viability of crop seed ingested by livestock is critical for good farm hygiene so that seeds are not inadvertently spread from the source paddock. Merino wethers were placed on a diet containing whole canola seed (10% total dry matter), and faeces were collected while canola was in the diet and for a further 6 days after canola was removed from the diet. Seed was found to pass through the wethers in less than 1�day, and reached a constant level after 2 days. When canola seed was removed from the diet, the majority of seed was passed during the first 2 days, but seed was excreted for up to 5 days. Seed germinability was reduced after 1�day, and further still after 2 days, but did not significantly decrease after this. While sheep are capable of excreting germinable canola seeds for up to 5 days after they were last included in the diet, use of a 7–10-day holding period will ensure that canola is not inadvertently spread beyond the grazed stubble paddock.
Publisher: International Seed Testing Association
Date: 07-2011
Publisher: Frontiers Media SA
Date: 09-01-2015
Publisher: Springer Science and Business Media LLC
Date: 08-2004
DOI: 10.1023/B:JOEC.0000042074.96036.14
Abstract: An investigation of the chemical basis for rice allelopathy to the rice weed arrowhead (Sagittaria montevidensis) was undertaken using GC/MS and GC/MS/MS techniques. Twenty-five compounds were isolated and identified from the root exudates of both allelopathic and non-allelopathic rice varieties. Phenolics, phenylalkanoic acids, and indoles were among the chemical classes identified. Two indoles previously unreported in rice were detected in the exudates, 5-hydroxy-2-indolecarboxylic acid and 5-hydroxyindole-3-acetic acid. Several other compounds identified in this study have not previously been reported in rice root exudates, namely mercaptoacetic acid, 4-hydroxyphenylacetic acid, and 4-vinylphenol. The levels of 15 compounds present in the exudates were quantified using GC/MS/MS. Six of the seven most abundant compounds were phenolic acids. Significant differences exist between the allelopathic and non-allelopathic cultivars in their production of three of these six compounds. Greater amounts of trans-ferulic acid, p-hydroxybenzoic acid, and caffeic acid were detected in the exudates of allelopathic cultivars. The seventh compound, abietic acid, was significantly higher in the non-allelopathic cultivars.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CP18355
Abstract: Herbicide resistance is a common occurrence in southern Australia. The evolution of herbicide resistance is influenced by the selection pressure placed on the weed species controlled by that herbicide. Results from resistance screening of ~4500 annual ryegrass (Lolium rigidum Gaud.) s les were entered in a GIS database, together with several agricultural parameters used in the Australian Bureau of Statistics Agricultural Surveys. This allowed a study of the associations between mode of action of resistance, geographic distribution of resistance across southern Australia, and farming practices employed in particular regions. Cultivation was negatively associated with resistances in acetyl-CoA carboxylase (ACCase)-inhibiting cyclohexanedione and acetolactate synthase (ALS)-inhibiting herbicides. Higher proportions of wheat sown were associated with higher incidences of resistance. ACCase-inhibiting aryloxyphenoxypropionate and cyclohexanedione and ALS-inhibiting resistances were higher in those shires where soils were predominantly acidic. This study demonstrates the association between farm practice and the evolution of herbicide resistance. The analysis provides reinforcement to the principle of rotating chemical modes of action with non-chemical weed control measures to minimise the risk of herbicide resistance evolution in any farming system.
Publisher: Elsevier BV
Date: 05-2010
Publisher: International Society for Horticultural Science (ISHS)
Date: 11-2016
Publisher: International Society for Horticultural Science (ISHS)
Date: 11-2016
Publisher: SAGE Publications
Date: 04-2005
DOI: 10.2201/NONLIN.003.02.006
Abstract: Based on the typical biological responses of an organism to allelochemicals (hormesis), concepts of whole-range assessment and inhibition index were developed for improved analysis of allelopathic data. Ex les of their application are presented using data drawn from the literature. The method is concise and comprehensive, and makes data grouping and multiple comparisons simple, logical, and possible. It improves data interpretation, enhances research outcomes, and is a statistically efficient summary of the plant response profiles.
Publisher: Wiley
Date: 14-12-2008
DOI: 10.1002/PS.1511
Abstract: Glyphosate resistance has been confirmed in 58 populations of Lolium rigidum (Gaud.), a major weed of crops in southern Australia. Extensive use of glyphosate in conjunction with minimal soil disturbance has been identified as high risk for resistance to that herbicide. Land managers need a simple method for rapid assessment of the risk of resistance occurring as a result of past and proposed future management practices. Modelled on risk assessment nomographs, a simple calculator for indicating the risk of evolved glyphosate resistance in L. rigidum is described. The calculator uses the generations since first use and the frequency of use of glyphosate in combination with historical cultivation levels as critical factors for determining the risk of glyphosate resistance evolution. Based on the management history of a field, a land manager can graphically determine a glyphosate resistance risk for that field. The calculator enables the farmer or the advisor to assess the risk of a weed's population becoming resistant and modify practices accordingly to manage for sustainable glyphosate use. The risk calculator could be modified for other herbicides and different weed species.
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/EA01069
Abstract: A trial was conducted to investigate the survival and digestibility of annual ryegrass (ARG) seed (Lolium rigidum L.) eaten by sheep and cattle. Sheep (n= 8) and cattle (n = 8) were fed a basal diet containing 1:1 lucerne chaff:oaten chaff with (ARG) or without (control) the inclusion of 20% total dry matter of annual ryegrass seed in a changeover design. Intake was restricted to 17 g/kg liveweight. Digestibility of the control diet was lower (P .01) for sheep than cattle. Annual ryegrass seed was present (P .01) in the faeces of both sheep and cattle within 24 h of first ingestion. Some 10.8 and 32.8% of seed ingested was excreted by sheep and cattle respectively, with 3.9% (sheep) and 11.9% (cattle) remaining germinable. Annual ryegrass seed continued to be excreted by both sheep and cattle up to 5 days after removal from the diet. Dry matter digestibility of the annual ryegrass diet was 53% in cattle.
Publisher: Elsevier BV
Date: 12-0004
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AR05394
Abstract: Four field experiments investigated strategies to reduce the negative effects of surface-retained wheat stubble on the emergence, growth, and yield of canola. All experiments compared 3 stubble treatments: (1) no stubble (stubble removed or burnt) (2) stubble-spread (6 t/ha wheat stubble evenly distributed on the surface) and (3) stubble-inter-row (6 t/ha stubble distributed on the inter-rows only). Seedling emergence was reduced in the presence of evenly spread stubble compared with no stubble, and the emerged seedlings had longer hypocotyls, reduced leaf number, and reduced biomass. Reduced shoot growth was not associated with lower shoot N concentration. These early effects on shoot growth persisted at 3 of the 4 sites, resulting in average yield reductions of 26% (range 0–59%) in the stubble-spread treatments compared with no stubble. Restricting stubble to the inter-rows resulted in an initial reduction in seedling growth compared with no stubble, but this difference had diminished by flowering. The yield for the stubble inter-row treatment was similar to no stubble at 2 sites and intermediate between no stubble and stubble-spread at the other 2 sites, with an overall yield reduction of 5.3% compared with no stubble. The results indicate that the negative effects on canola performance of surface-retained wheat stubble can be largely eliminated by adopting sowing techniques that push wheat stubble away from the seeding row and onto the inter-row. This provides a viable option to stubble burning and maintains the benefits of stubble retention.
Publisher: Springer Science and Business Media LLC
Date: 03-2006
Publisher: Springer Science and Business Media LLC
Date: 09-10-2014
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/RJ14090
Abstract: Food production research in rangelands depends heavily on the National Agricultural Research System for its research and development outcomes. Future outcomes are uncertain as funding sources are limited and much of the expertise is entering the retirement phase without a succession plan. Private research investment has contributed to some extent but there remains a need for governments to continue to support those aspects that deliver public good or address market failure. This review considers the varying contexts in funding and research organisation globally while using Australia as a case study for more detailed analyses of trends in livestock production research capacity in the rangelands. The major concern expressed is that the availability of a well educated and trained workforce is uncertain and this may h er rangelands from contributing sufficiently to global food security and national conservation goals.
Publisher: American Chemical Society (ACS)
Date: 22-06-2002
DOI: 10.1021/JF025508V
Abstract: The chemical basis for wheat seedling allelopathy on the growth of annual ryegrass was investigated by the identification and quantification of multiple allelochemicals from wheat seedlings. Results indicated that 58 wheat accessions differed significantly in seedling allelopathy and inhibited the root growth of ryegrass from 10 to 91%, depending on accession. Analysis of allelochemicals by GC/MS/MS indicated that allelopathy was significantly correlated with the levels of measured allelochemicals in the shoots and roots of young wheat seedlings. Ryegrass root growth was also negatively correlated with the levels of p-hydroxybenzoic, vanillic, and trans-ferulic acids in root exudates. Wheat allelopathic potential was negatively correlated with the levels of the eight known allelochemicals quantified in the shoots, roots, and water-agar medium, with multiple regression coefficients (r) of -0.61, -0.71, and -0.71, respectively. In comparison with weakly allelopathic accessions, strongly allelopathic accessions produced significantly higher amounts of allelochemicals in the shoots and roots of the wheat seedlings and also exuded larger quantities of allelochemicals into the growth medium. Wheat accessions with strong seedling allelopathy might be useful for management of weeds during the establishment stage, thereby reducing the need for commercial herbicides in early-season application.
Publisher: Informa UK Limited
Date: 2010
Publisher: Springer Science and Business Media LLC
Date: 12-2014
Publisher: American Chemical Society (ACS)
Date: 27-06-2003
DOI: 10.1021/JF026010W
Abstract: Thirty-nine wheat accessions were used to evaluate their extract phytotoxicity against annual ryegrass (Lolium rigidum Gaud.). Aqueous extracts of wheat shoot residues significantly inhibited the germination and root growth of a biotype of annual ryegrass resistant to herbicides of acetyl CoA carboxylase inhibitors (group A), acetolactate synthase inhibitors (B), photosystem II inhibitors (C), and tubulin formation inhibitors (D). The germination of the herbicide resistant (HR) biotype was inhibited by 3-100%, depending upon the wheat accession. The phytotoxic effects on ryegrass root growth ranged from 12% stimulation to 100% inhibition, compared to a control. The germination and root growth of a herbicide-susceptible (HS) biotype of annual ryegrass were also inhibited by the wheat extracts, with germination inhibited by 4-100%, and root growth by 19-100%. Bioassays with two known wheat allelochemicals showed that p-coumaric acid and propionic acid significantly inhibited the growth of both HR and HS biotypes of annual ryegrass. The two compounds completely inhibited the root growth of HR ryegrass at concentrations greater than 5.0 mM. In comparison with p-coumaric acid, propionic acid was more inhibitory to seed germination, shoot, and root growth of both ryegrass biotypes. The root growth of the HR biotype was more sensitive when exposed to wheat extracts, to p-coumaric acid, and to propionic acid. The results suggest that residues of certain wheat cultivars with strong allelopathic potential could provide a nonherbicidal alternative for the management of herbicide-resistant weed species.
Publisher: InTech
Date: 05-09-2018
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/EA04254
Abstract: Charles Sturt University commenced herbicide resistance monitoring in 1991. A random survey in 1991 to determine the level of resistance in annual ryegrass (Lolium rigidum) to selective herbicides across the south-west slopes region of New South Wales found that 30% of s les were resistant to at least 1 herbicide. A subsequent survey of commercially available ryegrass seed found that 58% of these s les were resistant to at least 1 herbicide. As a result of these findings, a commercial testing service was established and has since received s les from a large proportion of the southern Australian cropping belt. Seventy-seven percent of s les tested were resistant to Group AI, 40% to Group B and 22% to Group AII herbicides. Lower levels of resistance were found to Group D (8%), Group C (1%) and Group M (0.4%) herbicides. The correlation between resistance in Group AI and AII herbicides was lower than expected given that these herbicides are considered to have the same mode of action. Within the Group AI herbicides the observed response of the s les was consistent across herbicide formulations. Resistance to clethodim varied from observed responses to other Group AII herbicides. The variation in resistance levels (and degree of multiple resistance) in each Australian state is discussed in relation to environmental conditions and cultural practices. The size of this dataset allows for the analysis of the relationships present among herbicide resistant annual ryegrass.
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/EA04133
Abstract: Field experiments were conducted in southern New South Wales to determine the effect of surface-retained wheat stubble on the emergence, growth and yield of canola. The 5 experiments included treatments to investigate the impact of stubble load, stubble cultivar and level of decomposition as well as the impact of different environments on the crop response. Overall, 5 t/ha of surface-retained wheat stubble reduced the rate of emergence, plant establishment (mean reduction 33%), vegetative biomass (–56%) and yield (–23%), although the impact varied with site and season. Laboratory experiments assessing the phytoxicity of stubble revealed the possible role of allelopathy in the growth response at 1 site however, there was no correlation between laboratory phytotoxicity of different stubble cultivars and their impact on canola growth at any other site. Wheat stubble comprising thinner stems (lower straw linear density) had a greater impact on emergence at 2 of the sites, indicating a possible role of reduced light penetration in the growth response. Colder temperatures on the surface of the stubble also reduced emergence and growth, and caused seedling death at the coldest sites. The experiments confirm the widely observed phenomenon of poor canola growth in surface-retained wheat stubble, and suggest several possible mechanisms for the effect, although further studies are required to determine their relative importance in different environments.
Publisher: Springer Science and Business Media LLC
Date: 07-08-2003
DOI: 10.1007/S00122-003-1394-X
Abstract: Wheat ( Triticum aestivum L.) has been examined for allelopathic potential against annual ryegrass ( Lolium rigidum). The bioassay technique, 'equal-compartment-agar-method', was employed to evaluate seedling allelopathy in a doubled-haploid (DH) population derived from cv Sunco (weakly allelopathic) and cv Tasman (strongly allelopathic). A significant difference in allelopathic activity was found among the DH lines, which inhibited the root length of ryegrass across a range from 23.7 to 88.3%. The phenotypic data showed that wheat allelopathic activity was distributed normally within this DH population and a substantial transgressive segregation for seedling allelopathic activity was also found. Analysis of restriction fragment length polymorphism (RFLP), lified fragment length polymorphism (AFLP) and microsatellite (SSRs) markers identified two major QTLs on chromosome 2B associated with wheat allelopathy. The linkage analysis of genetic markers and the QTLs may improve genetic gains for the allelopathic activity through marker-assisted selection in wheat breeding. The development of wheat allelopathic cultivars could reduce the over-reliance of weed control on synthetic herbicides.
Publisher: Springer Science and Business Media LLC
Date: 2003
Abstract: An improved allelopathic correlation between phytotoxicity measured in root growth bioassay upon annual ryegrass (Lolium rigidum Gaud.) and the concentrations of a selection of dynamically produced allelochemicals quantified in the root exudates of cv. Khapli wheat (Triticum turgidum ssp. durum (Desf.) Husn.) monitored during the first 15 days of wheat seedling growth in a sterile, agar-water medium, has been established. Changes over the 15-day growth period in the quantities of five exuded benzoxazinones and seven phenolic acids were measured simultaneously using GC/MS/MS. Substantiating pure compound dose-response measurements were conducted over a range of concentrations for the putative allelochemicals within the wheat exudates. One synergism-based proposal using the monitored compounds to explain the observed low-exudate-concentration phytotoxicity was explored, but was found to be experimentally inadequate.
Publisher: Springer Science and Business Media LLC
Date: 22-03-2017
DOI: 10.1007/S10265-017-0921-9
Abstract: Alfalfa (Medicago sativa L.) genotypes at varying densities were investigated for allelopathic impact using annual ryegrass (Lolium rigidum) as the target species in a laboratory bioassay. Three densities (15, 30, and 50 seedlings/beaker) and 40 alfalfa genotypes were evaluated by the equal compartment agar method (ECAM). Alfalfa genotypes displayed a range of allelopathic interference in ryegrass seedlings, reducing root length from 5 to 65%. The growth of ryegrass decreased in response to increasing density of alfalfa seedlings. At the lowest density, Q75 and Titan9 were the least allelopathic genotypes. An overall inhibition index was calculated to rank each alfalfa genotype. Reduction in seed germination of annual ryegrass occurred in the presence of several alfalfa genotypes including Force 10, Haymaster7 and SARDI Five. A comprehensive metabolomic analysis using Quadruple Time of Flight (Q-TOF), was conducted to compare six alfalfa genotypes. Variation in chemical compounds was found between alfalfa root extracts and exudates and also between genotypes. Further in idual compound assessments and quantitative study at greater chemical concentrations are needed to clarify the allelopathic activity. Considerable genetic variation exists among alfalfa genotypes for allelopathic activity creating the opportunity for its use in weed suppression through selection.
Publisher: Wiley
Date: 08-2001
Publisher: Elsevier BV
Date: 2015
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/EA01097
Abstract: Winter cleaning is the removal of grasses from pasture using selective herbicides applied during winter. We compared the effectiveness of an early (June) and late (July) winter cleaning with an early spring herbicide fallow (September), spring (October) herbicide and no disturbance of the pasture on development of the root disease take-all in the subsequent wheat crop. Experiments were done at 5 sites in the eastern Riverina of New South Wales in 1990 and 1991. The winter clean treatments reduced soil inoculum of Gaeumannomyces graminis var. tritici (Ggt) compared with the other treatments at all sites as measured by a bioassay, with reductions from the undisturbed treatments of 52–79% over 5 sites. The winter clean treatments also significantly reduced the amount of take-all that developed in the subsequent wheat crop by between 52 and 83%. The early and late winter clean treatments increased the number of heads/m2 at 3 and 1 sites, respectively. Dry matter at anthesis was increased by the winter clean treatments at 3 sites. Grain yield was increased by the winter cleaning treatments over the other treatments at the 4 sites harvested, with yield increases of the early winter clean over the undisturbed treatment from 13 to 56%. The autumn bioassay of Ggt was positively correlated with spring take-all and negatively correlated with grain yield of the subsequent wheat crop at each site. However, there was a significant site and site × bioassay interaction so that the autumn bioassay could not be used to predict the amount of take-all that would develop.
Publisher: Springer Science and Business Media LLC
Date: 07-2001
DOI: 10.1007/BF02858100
Publisher: Informa UK Limited
Date: 03-06-2020
Publisher: Wiley
Date: 23-02-2011
Publisher: Wiley
Date: 04-07-2010
Publisher: Springer Science and Business Media LLC
Date: 2001
Abstract: The behavior and dynamics of 20 identified allelochemicals in vulpia residues were both collectively and in idually monitored, and their kinetic phytotoxicity was assessed. The total content of the identified allelochemicals in decaying vulpia residues increased from 0.31 to 1.24 mg/g dry residue over a 21-day decomposition period, while the total phenolic content increased from 1.86 to 2.16 mg/g dry residue. This corresponded to a phytotoxicity increase from 42% to 82% of radical inhibition. Allelochemicals changed in composition and quantity over the duration of the residue decomposition. Addition of soil to the residues reduced the total allelochemical contents extracted and altered the dynamic pattern. In the same period, the total content of allelochemicals declined from 0.061 to 0.046 mg/g residue + soil, with the total phenolics reduced from 0.20 to 0.11 mg/g residue + soil, corresponding to a radical length increase from 53% to 109% of control. Only 14 of the identified allelochemicals were detected in the mix of soil and residues, in contrast to 20 present in the residues alone. The implications of these findings are discussed.
Publisher: Elsevier BV
Date: 03-2016
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/AR06333
Abstract: Several weeds of rice in Australia have developed resistance to the main herbicide available for their control. Allelopathy is one phenomenon that could be incorporated into an integrated weed-management system as a supplement or alternative to synthetic herbicides. Several rice cultivars were screened both in the laboratory and the field for allelopathic potential against a major rice weed, Damasonium minus. Results from the laboratory bioassay showed that there were significant differences among cultivars in their ability to inhibit D. minus root growth. D. minus root lengths ranged from 2.0% (cv. Hungarian #1) to 32.6% (cv. Rexmont) that of the control. In the field study, significant differences existed in the D. minus dry matter grown in association with different cultivars, ranging from 4.6% (cv. Tono Brea) to 72.2% (cv. Rexmont) that of the control. Comparison between laboratory and field results indicated a strong relationship between performance in the field and in the laboratory (r2 = 0.713). Those cultivars ranked as allelopathic in the bioassay tended to have associated lower D. minus dry weight in the field. Eight of the top 10 allelopathic cultivars in the bioassay were among the top 10 suppressive cultivars in the field trial. This important finding indicates that at least some of the variation in field performance of cultivars may be predicted by their performance in bioassays.
Publisher: Springer Science and Business Media LLC
Date: 12-06-2007
Publisher: Springer Science and Business Media LLC
Date: 2001
Abstract: An analytical technique employing gas chromatography and tandem mass spectrometry (GC/MS/MS) was employed to systematically screen fifty-eight wheat accessions for their differential production of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) from three consecutive sources, i.e., the shoots, roots, and in the associated agar growth medium (collected as root exudates) of 17-day-old wheat seedlings. DIMBOA content differed significantly in the shoots, roots, or in the agar growth medium between accessions. DIMBOA accumulated differentially within the plant, with roots containing more DIMBOA than the shoots. Only 19% of accessions were able to exude DIMBOA from living roots into their growth medium, indicating the exudation of DIMBOA is accession-specific. DIMBOA level in root tissues is expected to be high when a high level of DIMBOA content is detected in the shoots. Wheat seedlings did not release detectable amounts of DIMBOA when the DIMBOA level was low in the root tissues. The valuable genetic material with high levels of DIMBOA in the shoots or roots identified in the present research could be used to breed for wheat cultivars with elevated allelopathic activity.
Publisher: Springer Science and Business Media LLC
Date: 08-2004
DOI: 10.1023/B:JOEC.0000042075.96379.71
Abstract: In previous studies, 15 putative allelopathic compounds detected in rice root exudates were quantified by GC/MS/MS. In this study, multiple regression analysis on these compounds determined that five selected phenolics, namely caffeic, p-hydroxybenzoic, vanillic, syringic, and p-coumaric acids, from rice exudates were best correlated with the observed allelopathic effect on arrowhead (Sagittaria montevidensis) root growth. Despite this positive association, determination of the phenolic acid dose-response curve established that the amount quantified in the exudates was much lower than the required threshold concentration for arrowhead inhibition. A similar dose-response curve resulted from a combination of all 15 quantified compounds. Significant differences between the amounts of trans-ferulic acid, abietic acid, and an indole also existed between allelopathic and non-allelopathic rice cultivars. The potential roles of these three compounds in rice allelopathy were examined by chemoassay. Overall, neither the addition of trans-ferulic acid nor 5-hydroxyindole-3-acetic acid to the phenolic mix significantly contributed to phytotoxicity, although at higher concentrations, trans-ferulic acid appeared to act antagonistically to the phytotoxic effects of the phenolic mix. The addition of abietic acid also decreased the inhibitory effect of the phenolic mix. These studies indicate that the compounds quantified are not directly responsible for the observed allelopathic response. It is possible that the amount of phenolic acids may be indirectly related to the chemicals finally responsible for the observed allelopathic effect.
Publisher: Springer New York
Date: 2008
Publisher: Informa UK Limited
Date: 17-09-2014
Publisher: American Chemical Society (ACS)
Date: 23-11-2015
Abstract: Widespread infection of Epichloë occultans in annual ryegrass in Australia suggests that infection provides its weedy host, Lolium rigidum, some ecological advantage. Initial studies determined the distribution and profiles of known Epichloë alkaloids (epoxy-janthitrems, ergovaline, lolines, lolitrem B, and peramine) in plant extracts using a combination of GC-FID and HPLC techniques utilizing a single accession of Australian L. rigidum. However, the lolines N-acetylnorloline (NANL) and N-formylloline (NFL) were the only alkaloids detected and were highly concentrated in the immature inflorescences of mature plants. Additional glasshouse studies subjected a wide range of Australian L. rigidum haplotypes and international annual Lolium accessions to a suite of analyses to determine alkaloid levels and profiles. Again, NFL and NANL were the key lolines produced, with NFL consistently predominating. Considerable variation in alkaloid production was found both within and between biotypes and accessions evaluated under identical conditions, at the same maturation stage and on the same tissue type. The pyrrolopyrazine alkaloid peramine was also present in 8 out of 17 Australian biotypes of L. rigidum and 7 out of 33 international accessions infected with Epichloë spp. the highest peramine concentrations were observed in seed extracts from L. rigidum collected from Australia. This study represents the first report of alkaloids from a geographically erse collection of annual ryegrass germplasm infected with Epichloë spp. when grown under identical controlled conditions.
Publisher: Elsevier BV
Date: 2010
Publisher: American Chemical Society (ACS)
Date: 29-06-2001
DOI: 10.1021/JF010111X
Abstract: Analysis by GC-MS/MS showed that a worldwide collection of 58 wheat accessions differed significantly in the amounts of 7 known phenolic acids exuded by the living roots of 17-day-old wheat seedlings. The quantities of exuded allelochemicals varied with the specific compound and ranged from 2.3 to 18.6, from 0.6 to 17.5, from 0.1 to 4.9, from 0.0 to 52.7, from 0.33 to 12.7, from 1.5 to 20.5, and from 1.6 to 23.4 microg/L of water/agar for p-hydroxybenzoic, vanillic, cis-p-coumaric, syringic, cis-ferulic, trans-p-coumaric, and trans-ferulic acids, respectively. The concentrations of p-hydroxybenzoic and vanillic acids exuded by wheat seedlings were normally distributed in the 58 accessions. The level of each phenolic acid in root exudates did not correlate well to that previously observed in wheat. In comparison with weakly allelopathic accessions, strongly allelopathic accessions exuded larger quantities of allelochemicals into the growth medium. The chemical basis for wheat seedling allelopathy is an area for further investigation.
Publisher: Scientific Research Publishing, Inc.
Date: 2020
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/AR03238
Abstract: Twenty-eight rice varieties with different countries of origin, maturity and stage of improvement were screened in the laboratory for allelopathic potential against arrowhead. Initial rice-density experiments established appropriate bioassay parameters and demonstrated that arrowhead response to rice root exudates follows a typical dose–response curve. Results from the equal compartment agar method (ECAM) bioassay showed that a range of allelopathic potential exists in rice germplasm. This work, together with other published studies suggests such potential to be species specific. In this study, the degree of root inhibition ranged from 26.6 to 99.7%. The potential allelopathic effect of arrowhead on rice seedlings was determined to be negligible.
Publisher: Cambridge University Press (CUP)
Date: 08-1999
DOI: 10.1017/S0043174500091992
Abstract: Glyphosate is the world's most widely used herbicide. It is nonselective and has been used to control a broad range of weed species for the past 20 yr, without the appearance of resistant weed biotypes. However, a biotype of Lolium rigidum from a field in Northern Victoria, Australia, in which glyphosate had been used for the past 15 yr, failed to be controlled by label recommended rates. Based on LD 50 values from pot dose-response experiments, this biotype exhibited resistance to glyphosate and was nearly 10-fold more resistant compared to the susceptible biotypes tested. The biotype was resistant to three different salts of glyphosate. The biotype was also nearly threefold more resistant to diclofop-methyl but was susceptible to other commonly used selective and broad-spectrum herbicides. Between the two-leaf and tillering stages of development, a susceptible biotype exhibited a small but significant decrease in tolerance to glyphosate, whereas tolerance of the resistant biotype remained unchanged with age. The resistant phenotype was verified in experiments in which seed was germinated in the presence of glyphosate. Observations on shoot and root growth of seedlings in these experiments suggested that the resistance mechanism might be associated more with the shoot than with the root.
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/AR07156
Abstract: Six Echinochloa species, i.e. barnyard grass (Echinochloa crus-galli (L.) Beauv.), awnless barnyard grass (E. colona (L.) Link), hairy millet (E. oryzoides (Ard.) Fritsch), prickly barnyard grass (E. microstachya (Wieg.) Rydb), Japanese millet (E. esculenta (A Br.) H Scholz), and channel millet (E. inundata Michael et Vickery), were detected in surveys of Australian rice fields in south-eastern Australia. Differences were detected in the rate of germination of species and this may affect the efficacy of herbicide treatments where mixes of species occur. Phenotypic variation within E. crus-galli, such as size of panicles, size of spikelets, and degree of awning, sometimes makes identification difficult and may have implications for seed growers. No instances of herbicide resistance were found in any Echinochloa species despite its widespread occurrence in other countries.
Publisher: Springer Science and Business Media LLC
Date: 03-2006
Publisher: Springer Science and Business Media LLC
Date: 18-02-2014
Publisher: Springer Science and Business Media LLC
Date: 2001
Abstract: Seven known phenolic acids implicated in wheat allelopathy were analyzed in a worldwide collection of 58 wheat accessions by gas chromatography and tandem mass spectrometry (GC-MS-MS). Chemical analysis showed that accessions differed significantly in the production of p-hydroxybenzoic, vanillic, syringic, trans-p-coumaric, cis-p-coumaric, trans-ferulic, and cis-ferulic acids in the shoots of 17-day-old wheat seedlings. The concentrations of p-hydroxybenzoic, vanillic, cis-p-coumaric, and cis-ferulic acids were normally distributed in the 58 accessions. A binormal distribution was found for syringic and trans-ferulic acids and a skewed normal distribution for trans-p-coumaric acid. The concentration of each compound also varied with phenolic acids. The relative abundance of each phenolic acid was ordered decreasingly as trans-ferulic, vanillic, trans-p-coumaric, p-hydroxybenzoic, syringic, cis-ferulic, and cis-p-coumaric acids. The concentration of total identified phenolic acids varied from 93.2 to 453.8 mg/kg in the shoots of 58 accessions. The content of each phenolic acid or group was highly associated with others in the shoots of wheat seedlings. Wheat accessions with high levels of total identified phenolic acids in the shoots are generally strongly allelopathic to the growth of annual ryegrass.
Publisher: Springer Netherlands
Date: 2014
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CP17455
Abstract: Annual ryegrass (Lolium rigidum Gaud.) is a troublesome invasive plant in southern Australian cropping systems and is typically infected with a fungal endophyte, Epichloë occultans. Potential links between herbicide resistance and endophyte infection were investigated in this study. We surveyed 391 ryegrass populations from geographically distinct, naturalised pasture and cropping areas across southern Australia and compared frequencies of seed-borne endophyte infection in the collected seed s les from mature annual ryegrass. Data on herbicide resistance from similar seedlots were cross-referenced with endophyte infection frequency to examine the potential relationship between herbicide resistance and endophyte infection. Seeds from cropping paddocks exhibited a significantly higher frequency of endophyte infection than pasture paddocks s led from the same region. Frequencies of endophyte infection in annual ryegrass declined across Australia during 2001–09, whereas the opposite trend was observed during 2009–12. Impacts of the Australian Millennium Drought, the correspondingly altered rainfall patterns and environmental selection pressures have a role in determining observed endophyte infection frequencies. However, there was no significant correlation between endophyte frequency and herbicide resistance in the populations evaluated. Differences in endophyte infection frequencies were associated with farming practices, and require further examination to determine causative selection pressures encountered in Australian field settings.
Publisher: International Seed Testing Association
Date: 28-04-2015
Publisher: Elsevier BV
Date: 08-2018
Publisher: Springer Science and Business Media LLC
Date: 09-2009
DOI: 10.1007/S10886-009-9689-2
Abstract: In a previous study, lavender (Lavandula spp.) was found to be highly phytotoxic towards annual ryegrass (Lolium rigidum, ARG), a major weed of winter wheat crops in Australia. This research aimed to further explore this relationship and determine the chemical(s) responsible for the observed effect. In bioassay, it was determined that the stem and leaf extract of L. x intermedia cv. Grosso ranked highest and had the potential to reduce significantly the root growth of several plant species. An extract concentration of 10% almost completely inhibited ARG root growth. When the extract was tested for stability, there was no loss in phytotoxicity after the 256 day trial. Via bioassay-guided fractionation and chromatographic techniques, it was determined that the sub-fraction consisting of coumarin and 7-methoxycoumarin was most phytotoxic towards ARG. Chemoassays of 18 structural analogues of coumarin showed that coumarin itself was the most phytotoxic and largely responsible for the observed phytotoxicity of the extract. Soil trials were conducted using pure coumarin and the lavender extract, and in both instances, shoot length and weight were significantly reduced by post-emergence application at all concentrations evaluated.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CP18584
Abstract: Charles Sturt University has operated a commercial herbicide resistance testing service since 1991, following a random survey of the South West Slopes region of New South Wales that identified significant incidence of herbicide resistance in annual ryegrass (Lolium rigidum Gaud.). Other surveys of cropping regions of southern Australia conducted at that time also found a significant incidence of resistance. In the subsequent 25-year period, the testing service has received s les from the majority of the southern Australian cropping belt. Overall, 80% of s les tested were resistant to acetyl-CoA carboxylase (ACCase) inhibiting aryloxyphenoxypropionate and phenylpyrazole herbicides, 56% to acetolactate synthase (ALS) inhibiting herbicides, and 24% to ACCase-inhibiting cyclohexanedione herbicides. The incidences of resistance to inhibitors of photosynthesis at PSII, tubulin-formation inhibitors, and 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase inhibiting herbicides have remained & % of s les tested. The relationships between many herbicide groups and subgroups are discussed, as is the variability in resistance incidence and the forms of cross or multiple resistance for each state. This paper builds on an earlier publication of 14 years of testing history. At & s les, the size and geographical spread of this dataset allows for valuable analyses of the relationships present in herbicide-resistant populations of annual ryegrass.
No related grants have been discovered for James Pratley.