Degree Of Phytotoxicity Research Articles

The composting potential of the by-product marc resulting from the white and red winemaking process

The production of an organic fertilizer was carried out, from waste generated in the winemaking process of white (Riesling Italian-RI) and red (Cabernet Sauvignon-CS) grapes obtained from the vineyard of Pietroasa (Romania). The potential of the biotransformation process of by-product marc in an open pile in the autumn-winter season was controlled and the thermophilic phase reached average values of 60 ºC at a neutral pH which gives it suitable characteristics to be used as a soil fertiliser. The values of the germination index (GI) of Lepidium sativum L. seeds, using water dilutions from the RI and CS compost marc, demonstrated that there was no degree of phytotoxicity (average GI 144.2% and 139.8%, respectively). The compost marc microflora was represented by bacterial and fungal isolates belonging to genera Rhizopus (10%), Aspergillus (80%), and Penicillium (17%), compared to by-product marc that only present fermentation yeasts. The structure of the microorganism populations in the compost marc dried by lyophilisation showed an almost double number of CFUg-1 compared to the oven-dried compost. The presence of potential antagonistic microorganisms and the high number of CFUg-1, demonstrated that this compost can have a suppressive effect on soil pathogens in addition to its quality as a fertilizer.

Gene introgression for imidazolinone group chemical herbicide tolerance

Genes of tolerance for herbicide has become one of the options more used in world level for the weed control. This study had as objective to evaluated crosses between tolerant irrigated rice plants and sensitive to herbicides of the imidazolinone chemical group, through the evaluation of F2 populations. Five genotypes of irrigated rice were crossed. Three of these parents are sensitive to the herbicide: BRS Querencia, BRS Fronteira and BRS Pampa and two genotypes, BRS Sinuelo CL and Puita INTA CL, tolerant to the herbicide. F1 seeds were obtained in greenhouse, and generation advance was performed in Embrapa Rice and Beans, resulting in the F2 population. F2 plants in the stage V4 received herbicide applications of (Only®) at a dose of 75 and 25 g a.i. L−1, and Dash® in dose of 0.5% v/v. A second application was performed after one week. The degree of phytotoxicity was scored as dead leaves and phytotoxicity intensity, percent survival of leaves and the relative growth. The results showed that the F2 hybrids, resulting of the crosses between the cultivars carriers of the gene of herbicide tolerance of the imidazolinone (Only®) class and conventional irrigated rice cultivars, are viable, thus enabling the establishment of herbicide-tolerant irrigated rice populations, with greater capacity to fight the red rice and with characteristics of agronomic interest. F2 progenies descending from crosses with the cultivar Puita INTA CL presented more tolerance when compared with progenies descending from crosses with the cultivar BRS Sinuelo CL.

Selectivity of herbicides applied, in pre-emergence, during the establishment phase of sugarcane

Sugarcane is a very important crop in the history of Brazil, since the period of colonization. Among the factors that affect its yield in commercial areas, weeds could be highlighted. Appropriate management strategies are essential to mitigate this interference and increase crop productivity. In this sense, the aim was to evaluate the effect of different control methods on weed management, in the pre-emergence of two varieties, of cane-plant. The experiment was conducted at Primavera Farm, Itambé (PE), in randomized blocks, in a 2x5 factorial scheme, with 4 replications. The first factor represented two varieties of sugarcane (RB867515 and RB92579) and the second five weed control methods (weed control, absolute control, s-metalochlor + tebuthiuron, sulfentrazone and oxyfluorfen). The number of tillers per linear meter, degree of phytotoxicity and weed control were evaluated. At the end of the research, the RB92579 variety can be used as an alternative for the weed control because it presents rapid sprouting and initial development and more aggressive tillering than RB867515, under Itambé (PE) soil conditions. It is recommended the use of sulfentrazone at the dose of 1.8 L.ha-1.p.c, for better residual effect and "sufficient" control of weeds in the stage of establishment of the culture.

Ecotoxicological Assessment of Roadside Soils in Areas along Leningradskoe Highway Using Laboratory Phytotesting

Roadside soils along Leningradskoe Highway are ecotoxicologically assessed by the laboratory phytotest method based on two test cultures. The research was carried out along a 300-m-long transect established perpendicular to the highway. The toxicity of soils, determined according to inhibition of the growth parameters of Lepidium sativum L. (cress) and Hordeum vulgare L. (rye), has been revealed in the majority of the studied area and is characterized by a bimodal distribution: it is maximum at a distance of several meters from the highway (dangerously and moderately toxic soils), sharply decreases at a distance of 7 m from it, and gradually increases again towards the end of the studied zone (moderately toxic soils). The degree of phytotoxicity is differentiated depending on the test culture variant: H. vulgare was characterized by a lower sensitivity to pollutants and did not reveal toxicity in the 7–25 m zone from Leningradskoe Highway, while L. sativum revealed toxicity of soils throughout the investigated area. Among the analyzed test parameters, root and seedling length were the most sensitive to pollutants, while seed germination was uninformative.

Time Matters: the Toxicity of Zinc Oxide Nanoparticles to Lemna minor L. Increases with Exposure Time

The use of zinc oxide nanoparticles (nano-ZnO) has rapidly increased in recent years, and this has triggered the need for versatile toxicity tests that can be used to test a range of different exposure scenarios. Acute exposure studies, using a variety of plant species, have overwhelmingly demonstrated nano-ZnO-induced toxicity, but substantial differences in the degree of phytotoxicity are reported in different studies. Here, we analysed the role of exposure time in determining the variation in phytotoxic effects. Using the model species Lemna minor, the effects of short-term (24 h), standardised (1 week) and chronic (up to 6 weeks) nano-ZnO exposure were compared. Nano-ZnO effects on Lemna minor growth indicators (biomass growth rate, root length), chlorophyll content and photosynthetic efficiency were measured. Rapid inhibitory effects of nano-ZnO on the maximal quantum yield of photosystem II could be measured after just 24-h exposure. Standardised (1 week) experiments revealed phytotoxic effects on Lemna minor biomass growth. More severe inhibitory effects on growth developed gradually over 4 to 6 weeks exposure to nano-ZnO, and these were qualitatively associated with increased zinc content in the plant. Such dynamics of nano-ZnO toxicity have not been elucidated before, and this study emphasises the importance of exposure time in studies of nanoparticle toxicity. We conclude that short-term, standardised experiments can potentially underestimate the environmental phytotoxicity, which may result from chronic exposure to nano-ZnO.

Мікробіологічна характеристика стічних вод м. Києва та оцінка екологічної придатності їх для використання в землеробстві

Мікробіологічна характеристика стічних вод м. Києва та оцінка екологічної придатності їх для використання в землеробстві

Wpływ typu gleby, pH, wilgotności i temperatury na fitotoksyczność i skuteczność zwalczania głowni cebuli (Urocystis magica Pass.) fungicydami z grup PCNB i TMTD [Influence of soil type, pH, moisture and temperature on phytotoxicity and effectiveness in control of onion smut (Urocystis magica Pass.) with fungicides of the groups PCNB and TMDT

Numerous experiments were performed in order to establish the influence of ecological factors such as soil type, pH, moisture and temperature on the degree of phytotoxicity towards onions as well as the effectiveness of such fungicides as Zaprawa Nasienna of the TMTD group, Terrafun 20, Terrafun 75, Brassicol and Liro PCNB-50 of the PCNB group in control of onion smut (<i>Urocystis magica</i> Pass.).

Phytotoxicity levels in a wet year in an experiment on maize sensitivity to herbicides

The phytotoxic effects of herbicides applied pre-, early post- and post-emergence were studied in maize in a herbicide sensitivity experiment were set up in Martonvásár and Törökszentmiklós. The herbicides were applied in normal and in double doses to 37 Martonvásár inbred lines and to six parental single crosses. The small-plot experiments were set up in two replications. The wet weather that followed the pre- and early post-emergence treatments promoted the appearance of phytotoxic symptoms on maize. The degree of phytotoxicity was recorded on the 14th day after post-emergence treatment and on the 14th and 28th days after the pre- and early postemergence treatments. Herbicides applied pre-emergence only caused slight symptoms on maize. Although the double dose increased the damage, it was still not more than 5% on average. The symptoms caused by herbicides applied in the early post-emergence stage were more intensive than those detected in the pre-emergence treatments. However, the damage caused by the double dose of isoxaflutol + thiencarbazone-methyl and by the split treatment with nicosulfuron remained below 10%. The symptoms became somewhat more severe at the 2nd scoring date. Among the post-emergence treatments the maize genotypes had the least tolerance of the mesotrione + nicosulfuron combination of active ingredients, where the double quantities resulted in 13–14% damage in average.

English

Bio-pesticides, when used as a post-planting pesticide, are limited by their potential ability to suppress the pest and their degree of phytotoxicity. Baseline information on the suitability of fermented crude extracts (FCE) of Cucumis africanus fruit as a post-planting bio-nematicide was determined on Meloidogyne incognita and growth of tomato in pot trials. Seedlings were inoculated with 1,130 eggs and juveniles/pot, while FCE were applied weekly at 0, 10, 20, 30, 40, 50 and 60% dilutions. At harvest, nematode and plant data were subjected to analysis of variance and the curve-fitting allelochemical response data (CARD) computer-based model, respectively. Relative to inoculation level, final nematode population density (Pf) at the same level of inoculation was reduced, while increasing dosages had no effect on Pf and reproductive factor values. Since increasing dosages had no effect on Pf, the material could possibly still reduce this variable when applied below 10% dilutions. Dosages used were phytotoxic to tomato plants, but CARD model demonstrated that the material stimulated plant growth at dosages below 10%. In conclusion, baseline information from CARD model suggested that FCE from C. africanus fruit have the potential to serve as a bio-nematicide and bio-fertiliser on tomato provided the material was applied below 10% dilutions. Key words : Cucumis africanus , bionemagation, effective microbe organisms, ground leaching technology, root-knot nematode.

Bell Pepper Seedling Phytotoxicity Due to Abscisic Acid Drench Applications

Bell pepper transplant height control is essential to produce a strong plant capable of surviving the transplant process. Transplant producers are interested in environmental, physical, and chemical methods to control plant height in the greenhouse. One emerging technology for transplant height control on bell pepper is the use abscisic acid (ABA); however, at high doses some phytotoxicity has been observed. Greenhouse experiments were conducted to determine the degree of phytotoxicity induced by an exogenous drench application of abscisic acid on ‘Aristotle’ bell pepper (Capsicum annuum L.), seedlings. Abscisic acid concentrations (1,000, 5,000, 10,000, 25,000, and 50,000 mg·L−1) were applied over a 1- to 5-week period beginning at the cotyledon stage, in addition to an untreated control. Plant survival for the control and the 1,000 mg·L−1 (baseline treatments) was significantly greater compared to a single application or multiple applications of greater concentrations. The results indicated that applying higher concentrations of ABA (5,000 mg·L−1 or more) using multiple lower concentration applications provided lower hazard ratios and increased longevity compared to a single higher concentration application. The ABA delivered as a drench at the cotyledon stage at concentrations of 5,000 mg·L−1 or below can control transplant height with no visible phytotoxicity.

Mean Dosage Stimulation Range of Allelochemicals from Crude Extracts of Cucumis africanus Fruit for Improving Growth of Tomato Plant and Suppressing Meloidogyne incognita Numbers

Successful utilisation of allelochemicals in management of plant-parasitic nematodes depends on their degree of phytotoxicity. Conventional methods of determining phytotoxicity are tedious, with inconsistent results. Plants respond to increased dosages of allelochemicals in a density-dependent growth pattern, which allows the use of the Curve-fitting Allelochemical Response Data computer-based model to determine the mean dosage stimulation range of used allelochemicals. The CARD modelling was used to determine the stimulation range of fermented dried crude extracts of wild cucumber (Cucumis africanus) fruit for improving growth of tomato (Solanum lycopersicon) plants, each infested with 1500 eggs and juveniles of the southern root-knot (Meloidogyne incognita) nematode. Dilutions at 0, 2, 4, 8, 16, 32 and 64% were applied weekly through irrigation system. At 56 days after treatment, CARD demonstrated density-dependent growth patterns as dosages increased. The mean dosage stimulation range of diluted fermented crude extracts, computed from CARD biological indices, was 2.64% dilution for tomato plant. Since at 2% dilution, the material reduced final nematode population density of M. incognita by 90%. The 2.64% was suitable for stimulation of tomato plant and suppression of nematode numbers.

Control of grassy weeds in annual canarygrass

There are currently no herbicides registered in Argentina for the selective control of grassy weeds in annual canarygrass ( Phalaris canariensis L.). The principal grassy weeds are darnel ryegrass ( Lolium temulentum L.) and wild oats ( Avena fatua L.), which cause grain yield and quality losses. The potential of diclofop-methyl and clordinafop-propargyl for their control was assessed through greenhouse and field trials, in which crop phytotoxicity and weed control efficacy were evaluated. It was found that (i) field application of clordinafop-propargyl resulted in severe crop damage, except for low doses that did not affect the species to be controlled; (ii) although field application of diclofop-methyl resulted in a certain degree of phytotoxicity on wild oats, these effects were insufficient for efficacious control; and (iii) field and greenhouse application of diclofop-methyl between 200 and 500 g a.i. ha −1 revealed differences between crop sensitivity and that of darnel ryegrass. In this range, crop phytotoxicity in the greenhouse was less than 20% compared to more than 60% in the weed, and in the field only slight crop phytotoxicity symptoms were observed. As in the greenhouse, field application resulted in significant phytotoxic effects upon darnel ryegrass, high efficacy levels, a low survival rate amongst treated plants and a notable reduction in seed production by surviving plants. Only the highest dose (500 g a.i. ha −1) in one of the field trials resulted in a significant reduction in crop grain yield. Hence diclofop-methyl application appears to offer a promising means for controlling darnel ryegrass.

Effects of red clover decomposition on phytotoxicity to wild mustard seedling growth

Previous studies have suggested that phenolics from legume green manures may contribute to weed control through allelopathy. The objective of this study was to determine how decomposition of red clover ( Trifolium pratense L.) residue affects phytotoxicity to a weed species, wild mustard ( Sinapis arvensis L.). Red clover (1.25 g), 30 g acid washed sand, and 5 ml of microbial inoculant were incubated in the dark at 14°C. The incubations were conducted in sand to allow the determination of decomposition phytotoxicity effects without being confounded by soil sorption effects. Aqueous extracts were collected at 0, 1, 2 and 5 weeks. The extracts were analyzed for dissolved organic carbon (DOC) and phenolic carbon (PhC). Phytotoxicity of the extracts was estimated by comparing root elongation under sterile laboratory conditions. The red clover extract significantly reduced radicle growth in the bioassay, but there was no significant change in the degree of phytotoxicity over the 5-week decomposition period. Although the concentration of DOC decreased with increasing decomposition, the PhC concentration was not significantly affected. This suggests that in the absence of soil sorbants, the phytotoxic compounds are stable throughout the 5-week incubation period and are phenolic in nature. This study demonstrates that the potential exists for using legume green manures to be a component of a sustainable weed management system, but indicates that soil characteristics need to be factored in evaluating the potential for this weed control tool.

Spray application factors and plant growth regulator performance: III. Interaction of daminozide uptake, translocation and phytotoxicity in bean seedlings

Effects of droplet size and carrier volume on foliar uptake and transport of daminozide were investigated. A constant dose of daminozide (100 µg per leaf) was applied to both primary leaves of 10-day-old Phaseolus vulgaris (cv Nerina) in droplet sizes of 1–10 µl and carrier volumes of 10 to 200 µl per leaf. Decreasing droplet size or increasing carrier volume decreased daminozide penetration, but increased translocation. Plotting the logarithm of the leaf surface/droplet interface area vs daminozide uptake yielded a negative linear relationship, but for translocation an optimum quadratic type relationship was obtained. Some phytotoxicity occurred at low carrier volumes and large droplet sizes. The degree of phytotoxicity was positively related to the amount of daminozide deposited per unit wetted area above 0.7 µg daminozide mm−2. Below this threshold, there was no visual evidence of phytotoxicity. At the breakpoint, the deposit covered an area of 276 mm2 on both primary bean leaf surfaces. Since the maximum in the relationship of translocation with interface area was in close agreement with the threshold amount of deposit above which phytotoxicity occurred, the inverse relationship between daminozide uptake and translocation at low interface areas was attributed to phytotoxicity. © 2000 Society of Chemical Industry

Isolation and characterization of phytotoxic compounds produced by Phomopsis helianthi.

The isolation, chemical characterization and biological activity of two phytotoxic metabolites of Phomopsis helianthi Munt-Cvet et al. is reported. These compounds were identified by spectroscopic methods (UV, IR, 1H and 13C NMR, and MS) as trans-4,6-dihydroxymellein (trans-3-methyl-4,6,8-trihydroxy-3,4-dihyroisocoumarin) and cis-4,6-dihydroxymellein (cis-3-methyl-4,6,8-trihydroxy-3,4-dihydroisocoumarin). This is the first report of the isolation of trans-4,6-dihydroxymellein from fungal cultures and of the production of cis- and trans-4,6-dihydroxymelleins by P. helianthi. Rice was found to be a good substrate for the production of the dihydroxymelleins. Culture extracts of some Italian and French strains of P. helianthi showed different degrees of phytotoxicity towards sunflower leaves and seedlings. The minimum effective doses of trans- and cis-4,6-dihydroxymelleins with different bioassays were 76 and 135 microg per spot (leaf puncture bioassay), 3 and 5 micromol g(-1) fresh tissue (absorption by leaf cutting) and 5 and 2 micromol g(-1) fresh tissue (absorption by cut seedlings), respectively. These compounds may contribute to the severity of the sunflower disease caused by P. helianthi.

Metal and arsenic impacts to soils, vegetation communities and wildlife habitat in southwest montana uplands contaminated by smelter emissions: II. Laboratory phytotoxicity studies

AbstractVegetation communities on metal‐ and arsenic‐contaminated uplands surrounding a smelter in southwest Montana have been eliminated or highly modified. Laboratory toxicity tests were performed using site soils from the impacted areas to determine whether the soils limit the ability of plants to establish and grow. The germination and growth of alfalfa, lettuce, and wheat in impacted area soils was compared to germination and growth of the three species in reference soils. The degree of phytotoxicity was quantified using a species‐endpoint toxicity score calculated on the magnitude of difference between germination and growth of plants in impacted and reference soils. The impacted soils exhibited substantial toxicity to plants: 5% of the sites were severely phytotoxic, 55% were highly phytotoxic, 10% were moderately phytotoxic, 20% were mildly phytotoxic, and 10% were nontoxic. Root growth was consistently the most affected endpoint (18 of 20 impacted soils) and reduction in root length and mass was observed. Correlation and partial correlation analysis was used to evaluate the causes of phytotoxicity. Concentrations of As, Cu, and Zn and, to a lesser extent, Pb and Cd were found to be positively correlated with phytotoxicity.

Light involvement in oxyfluorfen-induced protoporphyrin IX accumulation in several species of intact plants

Effect of light on diphenyl ether herbicide oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-trifluoromethylbenzene]-induced protoporphyrin IX accumulation in intact plants was investigated using five plant species which have different sensitivity to the herbicide. During 24 hr of dark incubation after 2 hr of shoot treatment with 1 μ M oxyfluorfen, protoporphyrin IX accumulation occurred in buckwheat and barnyard grass. When the plants were transferred to light after the dark incubation, a significant increase in protoporphyrin IX content was observed in rice and radish. In contrast, protoporphyrin IX was continuously decreased in buckwheat and barnyard grass in the light. Buckwheat was most susceptible to oxyfluorfen and its phytotoxic effect was detected after 2 hr of light exposure. In the plant, it was suggested that dark-accumulated protoporphyrin IX was involved in the rapid appearance of phytotoxicity in the light. By the determination of the accumulation rate in the light, it was shown that oxyfluorfen-induced protoporphyrin IX accumulation was increased by light in all plant species. This indicates that light acts as an enhancer of the accumulation in intact plants. However, profiles of protoporphyrin IX were considerably different among the tested species. Protoporphyrin IX contents in intact plants and the degree of phytotoxicity by oxyfluorfen were not always correlated.

The Effects of Five Herbicides onPinus patulaSaplings when Applied “Over-the-top” for Woody Weed Control

SYNOPSIS Five herbicides were applied over-the-top to Pinus patula saplings to determine which ones are tolerated by pines. At concentrations adequate for woody weed suppression, clopyralid and metsulfuron methyl were found most promising; glyphosate, fosamine-ammonium and triclopyr ester resulted in excessive tree mortality. Clopyralid was the only herbicide that did not affect tree growth during the first year after application, but after two years metsulfuron methyl did not significantly reduce growth either. All herbicide treatments caused varying degrees of phytotoxicity initially, but surviving trees recovered after 10 to 18 months to a state of no visible effects or permanent distortion. Stem distortion occurred only in the second year and was greatest in clopyralid.

Seed dressing insecticides for bean fly [Ophiomyia phaseoli(Tryon) (Diptera: Agromyzidae)] control in Ethiopia

Abstract Six seed dressing insecticides were tested for efficacy against Ophiomyia phaseoli (BF) in 1987 and 1988 at two locations in south‐central Ethiopia. Endosulfan and aldrin, at 5 g a.i./kg of seeds, were the least phytotoxic and the most effective. The rest gave variable results; BF control with some insecticides (e.g. furathiocarb) was comparable, but they showed varying degrees of phytotoxicity. The maximum seed yield loss was 36.5%. The results suggest that aldrin be replaced with endosulfan, which is less persistent.

Differential phytotoxicity among species and cultivars of the genus Brassica to wheat

Classhouse and laboratory studies were conducted to investigate the effect of microorganisms on the activity of water-soluble phytotoxins from Brassica residues, and on the persistence of the phytotoxins. Warm temperatures (20–24°C) and long incubation periods (20 to 40 days) were conductive to reduced phytotoxicity while low temperatures (0–4°C, regardless of incubation time), or short incubation time (regardless of temperature) resulted in levels of phytotoxicity similar to that found without incubation. The removal of microbial populations by micro-filtration resulted in the maintenance of phytotoxicity, regardless of the incubation conditions. The quantity of residues or extracts from residues used in a pot experiment and the soil type (sand or clay soil) determined the degree of phytotoxicity. Generally, the greater the quantity of residues or extracts, the greater the toxicity, with residues being more toxic than extracts from the same rate of residue. These observations agree with the general literature that the level of toxicity is determined by the quantity of residue present, and the rate of decline in the toxicity of water-soluble toxins is dependent on the microbial populations present, and their level of activity.