Adverse Effects Of Herbicides Research Articles

Sub-lethal effect of Round-up (a glyphosate-based herbicide) on juve-niles of African cat fish (Clarias gariepinus)

Herbicides have, no doubt, increased crop yields by killing different types of weeds, however, rainfall and irrigation can wash herbicides from sites of application into the water system. Fish has an important role in the food chain; therefore, investigation of the effects of Round-up on fish has a diag-nostic significance in evaluation of adverse effect of herbicides to human health. The sub-lethal effects of Round-up herbicide on juveniles of an Afri-can catfish Clarias gariepinus was investigated under laboratory conditions. The herbicide caused mortality of fish in a concentration dependent manner for the duration of exposure to acute concentrations (LC5O) of the herbicides for 96hrs.The lethal concentration (LC5O) value of glyphosate was gotten to be 0.560mg/1 for 96hr of exposure using Probit analysis. For the sub-lethal assay, standard haematological procedures were adopted to evaluate the blood parameters. There was significant reduction (p<0.05) in WBC, HGC, RBC, Lymphocyte and Monocyte in order of concentrations with respect to the control. There was also a significance increase (P<0.05) in MCV, MCH, MCHC and Platelet in order of concentration with respect to the control. The results of the biochemical properties showed that the level of total protein, glucose and total cholesterol were elevated with increase in concentration on exposure period of 8weeks compared to the control experiment(P<0.05). This clearly shows that the values were dose-dependent. The result from this study shows that Round-up has a toxic effect on C. gariepinus. This toxicity can end up in humans through the food chain.

Effects of weed management practices on soil microbial dynamics and yield of cabbage (Brassica oleracea var. capitata L.)

A field experiment was to study the effect of different weed management practices on Soil microflora and yield attributes and economics of cabbage. The results indicated that the T7 (weed free) recorded maximum value of plant height and earliest 50% head initiation, head maturity duration and yield attributing characteristics diameter of head, average head weight and head yield. It was followed by T1 [Pendimethalin 38.7 CS 0.7 kg a.i/ha (PE)+1 HW 30 DAT], T2 [Pendimethalin 30 EC 1.5 kg a.i/ha (PE)+1 HW 30 DAT], T6 (HW at 25 & 50 DAT). The number of bacterial, fungi and actinomycetes population was recorded with the treatment T8 (weedy check) compared to rest of the population. No significant difference noticed among the herbicide treatments. Beyond 40 days after application of herbicides and up to harvest, the population increased considerably in each case justifying no long term adverse effect of herbicides on the beneficial soil micro fauna and flora. The bacterial population was adversely affected, followed by fungi and actinomycetes in descending order. But at the time of harvest of the crop, the microbial population attained with all the treatments, the level equal to that of initial level or even more than original level in some treatments. The trend was similar in bacteria, fungi and actinomycetes. It is clear that the effect of herbicides on soil microbes is only temporary. The adverse effects of herbicides were gradually reduced with passage of time and practically, there was no adverse effect of herbicides on soil microbial activities in terms of fungi, bacteria and actinomycetes population after harvest of cabbage. Maximum gross return, net return was obtained with [Pendimethalin 38.7 CS 0.7 kg a.i/ha (PE)+1 HW 30 DAT] compared to rest of treatments.

Timing of seeding after herbicide application influences rates of germination and seedling biomass of native plants used for grassland restoration

Natural resource managers commonly use herbicides to control invasive weeds. This practice, however, can lead to secondary invasion by other invasive plants, unless measures such as seeding are taken to promote natives. Although there is evidence that seeding immediately after herbicide treatment adversely affects germination, there is little information on optimal timing between spraying and seeding or variation among species in herbicide sensitivity. We investigated effects of picloram and aminopyralid on seed performance of 10 native plants. We separated the herbicide application and seeding by 0, 3, 6, 9, and 11 months in a greenhouse, and recorded the rates of germination and germinant biomass after 6 weeks. In addition, we installed 72 field plots to test the effects of fall‐ and spring‐treated plots on seed performance. In the greenhouse, herbicides negatively impacted germination of four species over the entire 11‐month trail whereas six showed less sensitivity over time. Results from spring‐treated field plots were largely consistent with those from the greenhouse: rates of germination and biomass were lower in herbicide‐treated plots than those in control plots for 75% of seeded species. In fall‐sprayed plots, however, the adverse effects of herbicides were only apparent for 25% of seeded species. Results from greenhouse and field studies combined indicate that herbicides can have strong adverse effects on germination, but that actual effects in field settings will be based on complex interactions between species traits, field conditions, and management choices. Thus, site‐specific trials will ultimately be the best method for making inference to particular restoration sites.

Effect of organochlorine, pyrethroid and neonicotinoid insecticides on fragmentation and deletion rate of TP53 gene and primary DNA damage

Previous reports indicated adverse effect of herbicides on TP53 as a gene which damage promotes carcinogenesis. We evaluated three insecticides, with an emphasis on green agriculture, on their TP53 gene fragmentation and primary DNA damaging potential. Chlorpyrifos, α-cypermethrin as widely used representative of pyrethroids, and imidacloprid as a neonicotinoid, were tested in low concentrations equivalent of acceptable daily intake, residential exposure level, occupational exposure limit for each of insecticides. Common concentration of 3 µg/ml also was tested. Human peripheral blood lymphocytes were treated in extended cultures for 14 days. Comet assay endpoints, rates of TP53 gene fragmentation and deletion were assessed by comet-FISH technique. No increase in tail length or tail intensity compared to control (13.8±1.19 µm and 0.09±0.20% of DNA, respectively) was observed ; only for 3 µg/ml of imidacloprid tail length significantly increased (14.5±1.06 µm). Concerning TP53 structural integrity, no significant increase in rate of gene fragmentation or deletion was detected compared to control (6.7% and 3.3%, respectively). Statistically insignificant increase in TP53 migration in the comet tail was spotted at 3 µg/ml of α-cypermethrin (16.7%) and imidiacloprid (13.3%). Insignificant increase in TP53 deletion rate was observed for α-cypermethrin at 3 µg/ml (10.0%) compared to control (3.3%). Obsereved effects on level of primary DNA damage and TP53 structural integrity and copy number could not be considered biologically significant. At the low concentrations in extended term exposure applied in the study all three insecticides may be considered safe. This work was supported by Croatian Science Foundation under the project 8366.

Effect of herbicides on weed control and yield of kharifgroundnut (Arachis hypogaea L.)

A field experiment was carried out during kharif 2009-10 to 2011-12 at Agronomy Instructional Farm, C. P. College of Agriculture, S. D. Agricultural University, Sardarkrushinagar, Gujarat to study the effect of herbicides on weed control and yield of groundnut (Arachis hypogaea L.). Nine treatments of weed control were evaluated in randomized block design and replicated four times. Besides weed free treatment, an application of pendimethalin @ 1000 g/ha PE + imazethapyr 75 g/ha PoE at 15-20 DAS and H. W. + IC at 20 and 40 DAS recorded higher mature pods per plant, shelling percent, pod yield, haulm yield, gross return, net return, BCR and weed control efficiency as well as lower weed index and dry weight of weeds. No adverse effect of herbicides was observed on plant population, grain and straw yield of succeeding wheat crop.

The influence of herbicides on yield and grain quality of three winter wheat cultivarsOddziaływanie herbicydów na plonowanie oraz jakość ziarna trzech odmian pszenicy ozimej

Summary Field experiments were carried out in 2007–2009 to evaluate the effect of selected herbicides on yield and grain quality of three winter wheat cultivars (Tonacja, Satyna, Bogatka). Wheat plots were sprayed with Aminopielik D 450 SL (2,4-D + dicamba) at dose 3.0 l/ha, Mustang 306 SE (2,4-D + florasulam) at the dose of 0.6 l/ha and Sekator 6,25 WG (iodosulfuron metyl sodium + amidosulfuron) at dose of 300 g/ha. Herbicide treatment was made in the spring, at the stage of full tillering of wheat. At the time of harvest, grain yield was recorded and the the following grain parameters were determined: protein and gluten content, sedimentation index, falling number, weight of hectolitre and seeds grading. Wheat yield, grain milling value and flour baking value were strongly affected by the weather conditions and cultivars properties and only a slight effect of the used herbicides on grain parameters was stated. Herbicide Mustang 306 SE caused a significant yield reduction and seed grading weakness of Satyna cultivar as well as sedimentation index of Tonacja cultivar decrease. Herbicide Aminopielik D 450 SL reduced Bogatka cultivar yield. An adverse effect of herbicides on yield and grain quality was only recorded during the season with unfavorable weather conditions for winter wheat development.

In vitro studies on the effects of herbicides on the growth of rhizobia.

To study the possible adverse effect of herbicides on nodulation and nitrogen fixation in legumes by affecting the nitrogen-fixing rhizobia. Experiments were conducted to study the effect of four herbicides (terbutryn/terbuthylazine, trietazine/simazine, prometryn and bentazone) on the growth of nitrogen-fixing pea rhizobia (Rhizobium leguminosarum) in vitro by measuring optical density. Terbutryn/terbuthylazine, trietazine/simazine and prometryn had an adverse effect on the growth of rhizobia whereas bentazone was safe to rhizobia. The above herbicides could be used in pea at the recommended rates. The adverse effects of herbicides on rhizobia were observed at concentrations not normally expected to occur under field conditions. Further, previously observed adverse effects of these herbicides on nodulation and nitrogen fixation of peas were, possibly, not due to their effects in rhizobia but to their adverse effects on the plant growth itself.

Effect of weed-management practices on weed flora, soil micro-flora and yield of baby corn (Zea mays)

A field experiment was carried out during the winter seasons of 201011 and 201112 at Jaguli, West Bengal, on sandy-clay loam soil, to study the effect of different weed-control methods on weed growth, soil-microbial popu- lations and productivity of baby corn (Zea mays L.). Besides weed-free check, the higher yield of baby corn (1,464 kg/ha) was recorded with 2 hand-weeding done at 20 and 40 days after sowing (DAS) owing to significantly lower weed dry weight, higher weed-control efficiency (88.32%), lower weed index (4.63%) and increased nutrient up- take than the other treatments. This treatment was followed by straw mulch @ 10 t/ha and increased the yield by 68.98% over weedy check. Integrated weed-management practices like pre-emergence atrazine or metribuzin @ 1 kg/ha coupled with 1 hand-weeding at 30 DAS exhibited superiority to the respective atrazine or metribuzin @ 2 kg/ha alone. Straw-mulch treatment showed the maximum favourable effect on growth of non-symbiotic N-fixing and phosphate-solubilizing bacteria of soil. After the initial suppression, the adverse effect of herbicides on the bacterial population was recovered from 25 DAS. The maximum net returns ( 43,470/ha) were obtained with hand-weeding twice, but the highest benefit: cost ratio (2.43) was recorded under atrazine-treated plots.

The Environmental Benefits of Conservation Headlands in Cereal Fields

The cereal ecosystem is still the most important habitat for lowland gamebirds in Britain. Species such as pheasants and partridges, and indeed many other species of plants and animals, are known to thrive in cereal ecosystems throughout Britain, Northern Europe and North America if they are sympathetically managed. Techniques are now available to overcome the adverse effects of herbicides and insecticides on gamebird chicks and on a variety of species in the cereal ecosystem, among both its flora and its fauna. The basic approach has been to exclude pesticides selectively from the outermost six metres of the cereal crop, adjacent to the field boundary, a practice which has become known as Conservation Headlands. This article describes these techniques and charts their achievements to date.