Alternaria zinniae on Parthenium hysterophorus

Altemaria zinniae is reported for the first time on the weed Parthenium hysterophorus , at Udaipur, Rajasthan (IN).     

Behaviour of buried and surface-sown seeds of Parthenium hysterophorus

Parthenium hysterophorus L. seeds were buried at a depth of 5 cm for periods of 2–24 months to determine their longevity. The majority (73.7%) of these seeds were still viable after 24 months of burial. The remainder could not be recovered (18.0%) or were no longer viable (8.3%). There was a log-linear decline in persistence of germinable seeds over time, which indicated a constant rate of loss and a half-life of about 6 years. Seedling emergence from surface-sown seeds was also studied. Although there was considerable rainfall (31 mm), seedlings did not emerge during the first month of this experiment. In the succeeding 3 months, there was substantial seedling emergence after rainfall, and 51.4% of seeds had germinated by the end of the fourth month. After 5 months had passed, further seedling emergence was not detected, and intact seeds could not be located. These findings suggest that seed incorporation into the soil is important to the long-term persistence of P . hysterophorus seeds. In an initial test of germination, unburied seeds from the same seed lot exhibited a degree of innate dormancy, and this may explain the delayed germination observed in the surface-sown seeds. In the seed burial and recovery experiment, innate dormancy was lost after 2 months of burial in the field, although in situ germination of buried seed remained low for at least 24 months. Therefore, it appears that more than one dormancy mechanism may contribute to the persistence of P. hysterophorus seeds.     

Phytotoxic effects of Parthenium hysterophorus residues on three Brassica species

A study was conducted to assess the phytotoxicity of residues of Parthenium hysterophorus , an exotic invasive weed, towards the growth of three Brassica species ( Brassica campestris, Brassica oleracea and Brassica rapa ). The early growth of crops, measured in terms of seedling length and dry weight, was significantly reduced when grown in soil amended with varying amounts of Parthenium residues. A direct relationship was observed between the amount of residue incorporated in the soil and growth reduction. This adverse effect on Brassica crops indicates the presence of some growth-retardatory substances which are possibly released by the residues into the soil medium. In order to test this, aqueous extracts (1, 2, and 4%) of residues were prepared. It was observed that, in a laboratory bioassay, these extracts severely reduced the early growth of Brassica species, thereby indicating the presence of some water-soluble, inhibitory principles in Parthenium residues. A significant amount of the phenolics, the largest group of secondary metabolites usually implicated in allelopathy, was estimated in residue extracts, as well as in residue-incorporated soil. The phenolic content increased with increasing residue concentration, thereby showing their direct involvement in the observed growth inhibitions. Therefore, the study establishes that Parthenium residues exert an allelopathic influence on the early growth of Brassica crops by releasing water-soluble phenolics into the soil.     

银胶菊植株水浸提液对几种植物的化感作用

以萝卜、黄瓜、三叶鬼针草和马唐4种植物的种子为供试对象,测定了银胶菊植株水浸提液的化感活性.结果表明:(1)低浓度(0.01 g/ml)的银胶菊植株水浸提液对萝卜和黄瓜种子的萌发没有影响,相对萌发率均为100%,而对萝卜和黄瓜幼苗的生长却表现为促进作用,相对苗长分别为174.3%和103.9%,相对根长分别为151.9%和103.9%;(2)高浓度(0.5 g/ml)的银胶菊植株水浸提液对萝卜和黄瓜的种子萌发率、幼苗根长和苗高均表现为抑制作用,并随着浓度的提高,抑制作用增强;(3)不同浓度的银胶菊植株水浸提液对三叶鬼针草和马唐的种子萌发率、幼苗根长和苗高均表现为抑制作用,并随着浓度的提高,抑制作用增强.其中,当水浸提液浓度为0.5 g/ml时,三叶鬼针草和马唐的种子相对萌发率为0,受到强烈的化感作用.     

银胶菊对苘麻化感作用初步研究

通过室内培养皿法,研究了银胶菊水浸提液对苘麻种子萌发和幼苗生长的影响.结果表明,根、茎、叶、花水浸提液的化感作用强度存在差异,花、叶水浸提液对苘麻的化感抑制强度高于根、茎,且抑制强度随处理浓度的升高而增强;在20％浓度下,花、叶水浸提液完全抑制苘麻幼苗生长,对苘麻种子萌发的抑制率分别为91.9％、78.4％.     

Suppressive ability of selected fodder plants on the growth of Parthenium hysterophorus

Parthenium hysterophorus is an invasive weed in Australian rangelands. It displaces valuable fodder plants and causes significant production losses within the cattle industry. Glasshouse screening trials were used to test 20 selected fodder species (test species) for their suppressive ability against P. hysterophorus growth. The trials used two planting densities (four or six plants per pot) and five planting frequencies. Each density by planting frequency was replicated three times. The dry shoot biomass of the test species was used to calculate a suppression index, in order to rank the relative suppressive abilities of the test plants. Setaria incrassata, Panicum maxicum and Cenchrus ciliaris were ranked as strongly suppressive, while Astrebla squarrosa, Bothriochloa pertusa, Themeda triandra, Astrebla elymoides, Bothriochloa decipens, Eulalia aurea and Lablab purpureus were moderately suppressive. The other test species had only poor suppressive abilities. A second glasshouse trial assessed the growth characteristics of the test plants at 13, 27 or 40 days after transplantation (DAT). Test species that strongly suppressed the growth of Parthenium hysterophorus had several attributes that included the ability to attain a greater height, the rapid production of tillers or a branched canopy and an extensive leaf area and root system; these growth attributes were present as early as 13 DAT. The present glasshouse screening approach identified several fodder species for further testing in field trials, and because the attributes that allow the test species to suppress Parthenium hysterophorus are present at the earliest stages of the plant’s life cycle, a rapid screening method is proposed that assesses these attributes at 27 DAT.     

Pesticidal properties of parthenin (from Parthenium hysterophorus) and related compounds

Eleven sesquiterpene lactone derivatives of parthenin ( 1 ), obtained from wild feverfew, Parthenium hysterophorus, were prepared by chemical and photochemical transformations. The compounds tested were a pyrazoline adduct ( 2 ) of parthenin, its cyclopropyl ( 3 ) and propenyl ( 4 ) derivatives, anhydroparthenin ( 5 ), a dihydro‐deoxygenated product ( 6 ), a formate ( 7 ) and its corresponding alcohol ( 8 ) and acetate ( 9 ), a rearranged product ( 10 ), lactone ( 11 ) and hemiacetal ( 12 ). All these derivatives, along with parthenin, were tried for their antifeedant action against sixth‐instar larvae of Spodoptera litura, for insecticidal activity against the adults of store grain pest Callosobruchus maculatus, for phytotoxic activity against Cassia tora, and for nematicidal activity against the juvenile stage‐II (J₂) of the root knot nematode Meloidogyne incognita. Antifeedent bioassay revealed that parthenin is moderately antifeedant. Among the derivatives, the saturated lactone ( 11 ) was found to be about 2.25 times more active than parthenin. The pyrazoline adduct ( 2 ) was found to be the most effective as an insecticide, with LC₅₀ values after 24, 48 and 72 h of 96, 43 and 32 mg litre⁻¹, respectively, which are comparable with neem extract. Compound 4 was found to be the most effective inhibitor of germination and seedling growth of C tora, with ID₅₀ values for germination, plumule length and radicle length of 136, 326 and 172 compared with 364, 738 and 427 mg litre⁻¹, respectively, for parthenin. Compound 10 was found to be the most effective in terms of nematicidal activity. The LC₅₀ values for this compound were 273 and 104 mg litre⁻¹, respectively, after 48 and 72 h compared with 862 and 512 mg litre⁻¹ observed for parthenin after 48 and 72 h. © 2001 Society of Chemical Industry     

Host specificity testing and assessment of the pathogenicity of the rust, Puccinia abrupta var. partheniicola, as a biological control agent of Parthenium weed (Parthenium hysterophorus)

Parthenium hysterophorus, a native of Central America, is a problem weed of Australian rangeland, particularly in Queensland. Following field surveys in Mexico, the rust fungus Puccinia abrupta var. partheniicola was selected as a potential biological control agent. One isolate was chosen for further investigation after infection studies with one Kenyan and five Mexican isolates. Assessment of inoculation conditions showed that temperatures of less than 20° C and dew periods of more than 6 hours were required for abundant pustule production. Infection with the rust hastened leaf senescence, significantly decreased the life span and dry weight of Parthenium plants, and reduced flower production 10-fold. Subsequent host-range studies against 120 species and varieties, with further screening against a limited number of species conducted under a range of environmental regimes, indicated the rust to be sufficiently host-specific to be considered for introduction. Additional host-range tests against sunflowers demonstrated that resistance to P. abrupta var. partheniicola was not modified by prior inoculation with P. helianthi.     

Variation of Parthenium hysterophorus in response to soil quality: implications for invasiveness

Summary The performance of Parthenium hysterophorus , native to the tropical Americas and invasive to several countries, was evaluated for response to soil quality. Phenological (six stages) and quantitative growth variables [relative growth rates in height (R_h) and diameter (R_d)] were measured every fortnight. Based on harvest data, the variables, root:shoot (R:S) ratio, specific leaf area (SLA), relative growth rate in biomass (R_w), net assimilation rate (NAR) and dry matter allocation to plant components, were determined. High clay content in soils prolonged the rosette stage, enhanced R_h and R_d and hampered root growth, but promoted biomass allocation to shoots. The extreme degree of plant mortality was observed, with only 33.3% individuals surviving to reproduce in the soils with highest clay contents. This appears to be one of the most important findings that certainly has a major bearing on the range of adaptation of the weed. Seed mass declined whereas seed production increased in relatively coarser soils with the exception of nearly pure sand. In soils rich in clay, plants produced a smaller number of larger seeds. These data suggest that variation in fundamental functional traits would enable P. hysterophorus to adjust to a variety of habitat conditions.     

不同生境中银胶菊种群数量及其种群形成原因研究

银胶菊在路边、沟渠边、荒地、林地中发生较普遍,种群数量较大,其种子多集中于表土层。农田、果园中银胶菊发生面积较小,种群数量较少,其种子多集中在表土下1.5～10 cm处。银胶菊种子在土表0～0.5 cm处出苗率较高,而埋深1.5 cm以下,种子不能发芽出土。     

Utilization of Parthenium hysterophorus for the remediation of lead‐contaminated soil

A greenhouse experiment was conducted to study the role of plant growth regulators, a chelating agent, and plant growth‐promoting bacteria in lead (Pb) phytoextraction and their subsequent effect on the weed plant, Parthenium hysterophorus. Gibberellic acid (GA₃) and indole‐3‐acetic acid (IAA) were used as the foliar spray. Ethylenediamine tetra acetic acid (EDTA) was applied in split doses. Bacillus and Rhizobium strains were used as a single culture and as co‐cultures. The accumulation of Pb in different parts of the plant was analyzed by using an atomic absorption spectrophotometer. The amount of lead translocation and accumulation in the stems and leaves was significantly higher in the hormonal and EDTA treatments, while the microbial treatments showed no significant difference in the amount of Pb translocation into the stems and leaves, when compared to the control. The EDTA increased the amount of translocation into the shoots, but the dry biomass declined and subsequently reduced the total Pb phytoextraction. The GA₃ treatment showed the maximum total Pb accumulation, along with a higher dry biomass. The microbial co‐inoculated plants showed a significant increase in their dry biomass but the Pb accumulation did not increase like with the GA₃ and IAA treatments. These findings encourage the use of the GA₃ application for Pb phytoextraction by P. hysterophorus. One important feature of this weed plant is its unpalatable nature to herbivores, which could help in reducing the entrance of Pb into the food chain. Gibberellic acid is environmentally friendly compared to EDTA; therefore, more investigation of GA₃ and P. hysterophorus is required.     

恶性杂草银胶菊发生规律及综合除治措施初步研究

银胶菊是近年从美国传入的危险性杂草.通过对该杂草生物学特性、扩散途径、危害情况和除治药剂等的初步研究.提出了加强植物检疫及监测、物理和化学防除相结合的综合除治措施.     

Impact of Parthenium hysterophorus on grazing land communities in north‐eastern Ethiopia

An investigation into the impact of Parthenium hysterophorus infestation was conducted in 2007 in the north‐eastern grazing lands of Ethiopia. Data on the above‐ground and seedbank species diversity were collected from five areas, each having sites with low, medium, or high levels of weed infestation. A total of 72 species was found in all areas. They were categorized into grass species (23), other species (48), or P. hysterophorus for ease of interpretation. A regression analysis showed a highly significant, but negative, relationship between the above‐ground species diversity and evenness with P. hysterophorus abundance. The mean cover abundance for the three infestation levels was 33.4% for P. hysterophorus, 41.0% for the grass species, and 26.5% for the other species. The most dominant grass species under all infestation levels were Cynodon dactylon, Urochloa panicoides, and Chloris gayana, while Andropogon abyssinicus and Eragrostis spp. were dominant under the low and medium infestation levels, respectively, and Hyparrhenia hirta was dominant under the low infestation level. Among the other species, Solanum nigrum was the most dominant under the low infestation level and Datura stramonium and Xanthium spp. were the most dominant under the medium and high infestation levels, respectively. The above‐ground dry biomass of P. hysterophorus increased between the low and high infestation levels, while that of the grass or other species reduced in the high, as compared to the low, infestation level. Although the grass species density decreased significantly with successive increases in the P. hysterophorus infestation level, no such trend could be seen for the other species. Within the soil seed bank, the viable seed density for the grass species, other species, and P. hysterophorus were 25.7, 5.8, and 68.5%, respectively. Similarly, the soil seed bank under the low‐, medium‐, and high‐infestation sites was dominated by P. hysterophorus, which contributed 25.1, 65.4, and 87.4% of the viable seed bank, respectively. Although the overall similarity between the above‐ground vegetation composition and the soil seed bank was low, it was similar at the low‐infested site. Thus, the invasion by P. hysterophorus was found to critically endanger the biodiversity of the grazing lands, particularly for the different grass and forbs species in the area. These changes might adversely affect not only future agriculture, but also food security, unless appropriate practises are developed and implemented for P. hysterophorus management.     

The influence of temperature and photoperiod on growth and development of Parthenium hysterophorus L.

Germination, growth and flowering were investigated in Parthenium hysterophoms (Asteraceae), a species introduced to Australia and at present occurring as a weed in central Queensland. Combinations of day/night temperature regimes from 15/4 to 36/31 and day length of 10, 13 and 16 h in controlled conditions were examined to find the effects of any environmental restraints to growth and development. Results showed that individuals are able to germinate, grow and flower over a wide range of temperatures and photoperiods and established plants can survive at least one mild frost of — 2. We conclude that the potential distribution of P. hyslerophorus in Australia is much wider than at present. Future distribution of the species may be limited seasonally by the inability of seed to germinate in soils of low water potential and by the inability of seedlings to establish and grow at low light intensities.     

Parthenium hysterophorus in Nepal: a review of its weed status and possibilities for management

The rapid expansion of the alien invasive Parthenium hysterophorus is a new agricultural and environmental problem for Nepal. Although the weed was first recorded in 1967, the most significant expansion has occurred in the last 20 years. The weed is thought to have entered Nepal from India and currently is found in the Tarai, Siwalik and hill regions of Nepal. A CLIMEX modelling projection has shown these regions to be climatically suitable for the growth of P. hysterophorus, both under the present and a future projected increased temperature. From the initially invaded roadside vegetation, the weed has now spread into cropping land and forests. Vehicle movement and transportation of agriculture products are the main means by which its seed is spreading. The weed has reduced plant species richness and changed species composition in grasslands, while fodder collectors have developed contact dermatitis from the plant. To date, no sustainable management strategy has been developed for this weed. However, the fortuitous arrival of the biological control agents Zygogramma bicolorata and Puccinia abrupta var. partheniicola has had some impact upon the weed's growth and abundance. A CLIMEX modelling projection identifies many suitable locations for Z. bicolorata outside of its present range and within areas where the weed is likely to spread, both under the present and under a future projected climate of increased temperature. Mapping of the currently invaded areas, management through community involvement and further releases of new and redistribution of current biological control agents are required to manage P. hysterophorus in Nepal.     

Biology,ecology and management of the invasive parthenium weed (Parthenium hysterophorus L.)

Parthenium weed (Parthenium hysterophorus L.) is one of the most aggressive invasive weeds, threatening natural ecosystems and agroecosystems in over 30 countries worldwide. Parthenium weed causes losses of crops and pastures, degrading the biodiversity of natural plant communities, causing human and animal health hazards and resulting in serious economic losses to people and their interests in many countries around the globe. Several of its biological and ecological attributes contribute towards its invasiveness. Various management approaches (namely cultural, mechanical, chemical and biological control) have been used to minimise losses caused by this weed, but most of these approaches are ineffective and uneconomical and/or have limitations. Although chemical control using herbicides and biological control utilising exotic insects and pathogens have been found to contribute to the management of the weed, the weed nevertheless remains a significant problem. An integrated management approach is proposed here for the effective management of parthenium weed on a sustainable basis. © 2014 Society of Chemical Industry     

Rising CO2 can alter fodder–weed interactions and suppression of Parthenium hysterophorus

Three C₄ grass (Setaria incrassata, Astrebla squarrosa and Bothriochloa decipiens) and one C₃ legume (Clitoria ternatea) suppressive fodder species, were re‐evaluated against the growth of the C₃ Parthenium hysterophorus under an ambient (390 μmol mol^?1) and an elevated atmospheric CO₂ concentration (550 μmol mol^?1). Under the elevated atmospheric CO₂, shoot dry biomass and suppression index (SI) value of the C₄ S. incrassata were both reduced by 32% and 0.7 respectively, while those for A. squarrosa were reduced by 23% and 0.3. In contrast and under the same elevated atmospheric CO₂ concentration, the shoot dry biomass and SI of the C₄ B. decipiens were increased by 8% and 0.1 respectively, while those for the C₃ C. ternatea were increased by 38% and 0.8. Our results suggest that C₃ fodder plants along with certain C₄ species could be utilised for the effective management of P. hysterophorus under the future elevated atmospheric CO₂ conditions. However, this system needs more fodder species to be investigated. Our results suggest that rising CO₂ per se may alter the efficacy of suppressive fodder management of an invasive C₃ species, P. hysterophorus.     

Phytotoxic effect of Parthenium residues on the selected soil properties and growth of chickpea and radish

The present study investigates the effect of residues of noxious weed Parthenium hysterophorus in soil as well as under laboratory conditions. Soils were infested with different amounts of Parthenium residues to determine the changes in soil chemistry, phenolic content and the phytotoxic effects on crops like chickpea ( Cicer arietinum ) and radish ( Raphanus sativus ). The modified soils and unmodified (control) soil were analyzed for pH, conductivity, organic carbon, organic matter, available nitrogen, phosphorus, potassium and micronutrients such as sodium, iron, manganese and zinc. The pH of all the modified soils decreased whereas the conductivity, organic carbon and organic matter increased. Further, the amount of sodium and potassium increased, whereas that of zinc decreased. In the soil infested with 4 g of Parthenium residue, the amount of available nitrogen decreased. The presence of significantly high amounts of phenolics in all modified soils indicated their possible interactions with soil chemical properties. This was also indicated by the correlation analysis between phenolics and various soil properties. The growth studies carried out in the modified soils indicated their phytotoxic nature, as seedling growth of both chickpea and radish was significantly decreased compared with seedlings grown in unmodified soils. The extracts prepared from Parthenium residues were also found to be phytotoxic to both the test crops and were also rich in phenolics. The presence of phenolics in Parthenium residues and their interference with soil chemistry upon release may be responsible for a decrease in the growth of radish and chickpea.