chlorophyll-a and tebuconazole

The alkaline single-cell gel electrophoresis assay (comet assay) was used for the study of the genotoxic effects of insecticide Chlorpyrifos and fungicide Tebuconazole (commercial formulations) on two freshwater green algae species, Pseudokirchneriella subcapitata and Nannocloris oculata, after 24 h of exposure. The percentage of DNA in tail of migrating nucleoids was taken as an endpoint of DNA impairment. Cell viability was measured by fluorometric detection of chlorophyll "a" in vivo and the determination of cell auto-fluorescence. Only the higher concentration of Chlorpyrifos tested resulted to affect significantly the cell viability of P. subcapitata, whereas cells of N. oculata were not affected. Tebuconazole assayed concentrations (3 and 6 mg/l) did not affect cell viability of both species. The results of comet assay on P. subcapitata showed that Chlorpyrifos concentration evaluated (0.8 mg/l) exerted a genotoxic effects; while for the other specie a concentration of 10 mg/l was needed. Tebuconazole was genotoxic at 3 and 6 mg/l for both species. The comet assay evidenced damage at the level of DNA simple strains molecule at pesticide concentrations were cytotoxicity was not evident, demonstrating that algae are models to take into account in ecological risk assessments for aquatic environments.

Topics: Cell Survival; Chlorophyll; Chlorophyll A; Chlorophyta; Chlorpyrifos; Comet Assay; DNA Damage; Fungicides, Industrial; Insecticides; Mutagens; Triazoles

Tebuconazole is a triazole systemic fungicide that is commonly used to treat fungal pathogens of crops, but at high doses can reduce seed germination. Seeds with microcapsulated tebuconazole were investigated to determine effects of this method on maize seedlings and the bioefficacy against maize head smut (Sphacelotheca reiliana). The ethyl cellulose (EC)-based microcapsules had encapsulation efficiency of 90.6%, and average size of 1.6 μm. A release kinetic study revealed that tebuconazole release from EC-based microcapsules fits the model (Mt/Mz=kt(n)+C). Glasshouse studies indicated that maize seedling emergence and growth were negatively affected in an exponential manner as predicted by model Y=A+B×e((-x/k)). However, microencapsulation could induce tebuconazole's growth promoting effects by increasing emergence, shoot fresh weight, root fresh weight, carotenoid and chlorophyll content. Phytohormone analysis indicated the beneficial effects of microencapsulated tebuconazole were due to the sustained release of tebuconazole that appeared to influence the balance of phytohormones in maize seedlings. Contrary to conventional tebuconazole, microencapsulated seed-coated tebuconazole can lead to slightly increased gibberellins (GA) level and disappearance of abscisic acid (ABA) accumulation in maize. In addition, microcapsule formulation of tebuconazole was found to provide better protection against maize head smut when compared to conventional formulation.

Topics: Abscisic Acid; Biomass; Capsules; Carotenoids; Chlorophyll; Drug Compounding; Gibberellins; Kinetics; Microscopy, Electron, Scanning; Photosynthesis; Plant Diseases; Plant Leaves; Seedlings; Seeds; Triazoles; Water; Zea mays

This study explored the chronic and harmful effects of different doses of the triazole fungicide, tebuconazole, on the growth, and metabolic and enzymatic variations in the filamentous paddy field cyanobacterium, Westiellopsis prolifica Janet. The growth of the cyanobacterium was determined by an estimation of the change in pigment contents. Chlorophyll-a, carotenoids and accessory pigments such as phycocyanin, allophycocyanin and phycoerythrin, were shown to decline over a 16-day period by a factor of 92%, 93%, 83%, 95% and 100%, respectively, with increasing doses of the fungicide. Metabolic and enzymatic activities were also adversely affected. Over the 16 days, a gradual rise in the total phenol content was recorded when Westiellopsis prolifica Janet was treated with 60 ppm of the fungicide, despite the reduction in carbohydrates, proteins and amino acids by 96%, 92% and 90%, respectively. Moreover, the enzymes nitrate reductase (NR), glutamine synthetase (GS) and succinate dehydrogenase (SDH) also registered reductions of 93%, 90% and 98%, respectively. This study indicates that tebuconazole, although an important fungicide used extensively in rice fields, exhibits an inhibitory effect on the growth and metabolic activities of Westiellopsis prolifica Janet and hence possibly on other varieties as well.

Topics: Carotenoids; Chlorophyll; Chlorophyll A; Cyanobacteria; Fungicides, Industrial; Glutamate-Ammonia Ligase; Nitrate Reductase; Nitrogen Fixation; Oryza; Phycocyanin; Phycoerythrin; Triazoles

Strobilurin fungicides have a broad spectrum activity against all major foliar pathogens of wheat. In addition to this extraordinary fungicidal activity side-effects have been reported which result in higher yields of cereals, e.g. the reduction of respiration, delayed leaf senescence, activation of nitrogen metabolism as well as increased tolerance against abiotic stress factors. In the vegetation period 2000/2001 field trials were carried out at three sites in North Rhine-Westphalia to study the effects of three strobilurin fungicides on the yield formation of six winter wheat varieties. The strobilurins were applied two times as the commercial products Stratego (trifloxystrobin + propiconazole), Amistar/Pronto Plus (azoxystrobin/spiroxamine + tebuconazole) and Juwel Top (kresoxim-methyl + epoxiconazole + fenpropimorph. Fungicide-treated plants were kept disease-free by an initial azole-application in GS 31 in order to exclude disease effects on physiological parameters relevant to yield formation. Photosynthetic electron transport of strobilurin-treated wheat, was improved as early as at GS 65 compared to azole-treated plants. Differences often increased with growth stage and were closely related to a delay in leaf senescence. A higher photosynthetic activity of strobilurin-treated plants was confirmed by gas exchange and chlorophyll fluorescence measurements under field conditions. The yield benefit of wheat from strobilurin treatments varied from 2% to 9% depending on an improved photosynthetic capacity due to a higher and/or prolonged activity. Neither yield potential nor disease susceptibility of the cultivar had an effect on the height of the extra yield which, in contrast was modified by location and wheat genotype.

Topics: Acetates; Acrylates; Azoles; Chlorophyll; Epoxy Compounds; Fungicides, Industrial; Germany; Imines; Methacrylates; Morpholines; Phenylacetates; Photosynthesis; Pyrimidines; Strobilurins; Triazoles; Triticum