Phytotoxic effects of essential oils from Nepeta glocephalata Rech.f. and N. ispahanica Boiss. on se-lected weed species

<p class="042abstractstekst">In the present study the bioherbicidal activity of essential oils hydrodistilled from <em>Nepeta glocephalata </em>Rech.f and <em>N</em>. <em>ispahanica</em> Boiss were investigated on four weed species (barnyard grass (<em>Echinochloa crus-galli</em> (L.) Beauv), redroot pigweed (<em>Amaranthus retroflexus </em>L.), lambsquarters (<em>Chenopodium album </em>L.) and canary grass (<em>Phalaris canariensis </em>L.)). A total of 37 components were identified from the essential oils of <em>N. glocephalata and N. ispahanica</em> constituting approximately 98.61 % and 96.1 % of the oils, respectively. In laboratory bioassay different concentrations (0, 1, 2, 4 and 8 μl ml^-1) of two <em>Nepeta </em>essential oils on germination, root and shoot length were studied. Results showed by increasing the concentration of oils, all studied traits of the weeds were decreased compared with control. In a glass house bioassay post-emergence application of <em>Nepeta</em> essential oils (1.25 %, 2.5 %, 5 % and 10 %, v/v) on 3-week-old weed plants caused visible injury (7-days after spray) ranging from chlorosis to necrosis of plant weeds. In foliar application under glasshouse conditions, both<em> Nepeta</em> essential oils reduced the seedling dry mass and concentrations of chlorophyll a chlorophyll b. The study concludes that <em>Nepeta</em> essential oils have phytotoxic effects and could be used as bioherbicides but the selectivity of these compounds should be considered also.</p>

Biotesting of polymeric waste excluded from solid waste waste

Introduction. Annually, the volume of accumulated polymers in landfills in Ukraine is growing by more than 1 million tons, but the volume of recycled polymer packaging over the past ten years has not exceeded 3%. The goal is to establish the degree of toxicological impact on biosphere objects of polymers extracted from solid waste, to assess the safety of using household polymer waste as a secondary raw material for further processing. The task is to establish the degree of biological and toxicological safety of polymer wastes extracted from solid waste. Methods and techniques: toxicological - determination of water toxicity on acute Daphnia magna according to DSTU 4173: 2003 (ISO 6341: 1996, MOD) and chronic according to DSTU 4166: 2003 (ISO 10706: 2000, MOD), and Paramecium caudatum ciliates, soil microflora reactions (saprotrophic soil bacteria CFU / g) according to MR 2609-82, the assessment of phytotoxic effects on higher plants was carried out by vegetation methods according to ISO 17402-2008, ISO 17126-2005a, ISO 22030: 2005b, ISO 11269 -1:2012a. Results. The research results show that aqueous extracts from waste polymers extracted from solid waste and their mixture do not have a pronounced toxic effect on aquatic organisms. There is no significant effect on soil bacteria. The study of the effect of polymer waste on seed germination did not reveal phytotoxic effects for any crop. A slight phytotoxic effect was observed during the study of PVC and PS waste. Wheat and mustard were the most sensitive. The level of phytotoxic effect was within acceptable limits and did not exceed 5.67%. Evaluation of phytotoxic effects on stem length showed the presence of effects from all processed products except PVC. The impact, characterized as weak, ranged from - 2.06% (PP) to - 13.27% (PS). The effect on root length was found for samples with PS waste (-7.23%), which was characterized as weak and PVC (-43.52%) - medium. Watercress and mustard were the most sensitive plants to the effects of polymer waste. Conclusions. The studied samples of polymer waste do not show hygienically significant toxic effects on water and soil test objects, even in concentrations of 1: 1, so the impact on the above test organisms polymer waste removed from solid waste is classified as hazard class 4. According to the assessment of phytotoxic effect, polymer waste removed from solid waste is classified as hazard class 4, except for PVC - hazard class 3.

Chlorophyll Fluorescence Imaging-Based Duckweed Phenotyping to Assess Acute Phytotoxic Effects

Duckweeds (Lemnaceae species) are extensively used models in ecotoxicology, and chlorophyll fluorescence imaging offers a sensitive and high throughput platform for phytotoxicity assays with these tiny plants. However, the vast number of potentially applicable chlorophyll fluorescence-based test endpoints makes comparison and generalization of results hard among different studies. The present study aimed to jointly measure and compare the sensitivity of various chlorophyll fluorescence parameters in Spirodela polyrhiza (giant duckweed) plants exposed to nickel, chromate (hexavalent chromium) and sodium chloride for 72 h, respectively. The photochemistry of Photosystem II in both dark- and light-adapted states of plants was assessed via in vivo chlorophyll fluorescence imaging method. Our results indicated that the studied parameters responded with very divergent sensitivity, highlighting the importance of parallelly assessing several chlorophyll fluorescence parameters. Generally, the light-adapted parameters were more sensitive than the dark-adapted ones. Thus, the former ones might be the preferred endpoints in phytotoxicity assays. Fv/Fm, i.e., the most extensively reported parameter literature-wise, proved to be the least sensitive endpoint; therefore, future studies might also consider reporting Fv/Fo, as its more responsive analogue. The tested toxicants induced different trends in the basic chlorophyll fluorescence parameters and, at least partly, in relative proportions of different quenching processes, suggesting that a basic distinction of water pollutants with different modes of action might be achievable by this method. We found definite hormetic patterns in responses to several endpoints. Hormesis occurred in the concentration ranges where the applied toxicants resulted in strong growth inhibition in longer-term exposures of the same duckweed clone in previous studies. These findings indicate that changes in the photochemical efficiency of plants do not necessarily go hand in hand with growth responses, and care should be taken when one exclusively interprets chlorophyll fluorescence-based endpoints as general proxies for phytotoxic effects.

Characterizing the Phytotoxic Effects of Hydrogen Peroxide Root Dips on Hybrid Phalaenopsis Orchid Plants

Hydrogen peroxide (H2O2) is a well-known oxidizing agent often used as a remedy by consumers to treat algae and root decay from presumed root disease on interior plants, as well as to encourage root growth and health. To characterize the phytotoxic effects and define the safe concentration threshold for H2O2 use on ‘Vivaldi’ hybrid phalaenopsis orchid (hybrid Phalaenopsis), root systems were dipped for 3 minutes in 0%, 3%, 6%, or 12% H2O2 one time and observed in greenhouse conditions for the following 27 days. Root systems of each plant were assessed over time for percent visible root damage; ratings of root health on a scale of 1 to 5 points, with 5 points indicating “very healthy”; and final fresh and dry weights. To determine when symptoms manifested above the root zone, foliage and flower damage was evaluated over time by assessing percent visible foliage damage, ratings of foliage health, percent foliar wilt, flower/bud count, and final foliage and flower fresh and dry weights. Over the evaluation period, the root health rating of the ‘Vivaldi’ hybrid phalaenopsis orchids treated with 12% H2O2 decreased from 5 to 1.13, whereas those treated with 3% H2O2 only decreased from 5 to 4.13. H2O2 concentrations of 6% and 12% damaged root health permanently, whereas the 3% H2O2 concentration only caused minor damage to overall root health. However, algae were not killed at the 3% rate. Neither foliage nor flowers were seriously affected during the 3 weeks after application, but foliage wilt did result in the 6% and 12% treatments by week 4. As H2O2 concentration increased, fresh weights decreased in roots and leaves. Although a single 3% H2O2 root dip did not result in severe symptoms of phytotoxicity, the treatment’s long-term plant health effects are unknown. Because the 3% H2O2 root dip caused minor plant health setbacks and failed to subdue algae populations in the root zone, consumers should be wary of using H2O2 to improve orchid (Orchidaceae) root health and should instead focus on altering care and watering practices.

Auxin-type herbicide drift: effects on grapevine leaf functioning and reproductive performance

Auxin-type herbicides are widely used to control broad-leafed weeds in cereal crop fields and pastures. Vapour drift, however, can spread several kilometres and therefore reach nearby vineyards. When grapevines are exposed to these chemicals, the active constituents induce phytotoxic effects including injury to foliage and impairment of reproductive development. The aim of this article is to outline the key potential implications of auxin-type herbicide drift exposure on leaf functioning and grapevine reproductive performance.

Biorational and conventional insecticides efficacy to control thrips (Frankliniella occidentalis Perg.) on strawberries (Fragaria x ananassa Duch.) at Morelos state, Mexico

Objective: To evaluate the insecticidal effectiveness of biorational and conventional products as alternatives to control thrips and their phytotoxic effects in strawberry cultivation. Design / methodology / approach: The research was carried out in strawberry cv. Camino Real during its flowering stage - fruiting established in open ground; A completely randomized experimental design with seven treatments and four replications was used. The treatments evaluated were: T1: neem oil extract, T2: paraffin oil, T3: garlic extract + hot chili pepper + cinnamon, T4: spinosad, T5: imidacloprid + lambda cyhalothrin, T6: bifenthrin, and T7: control. Applications were made weekly and the mortality evaluation was carried out by counting the number of live thrips per flower. With the obtained data, an analysis of variances and a mean comparison test (Tukey, p ≤ 0.05) were performed. Results: Significant differences between treatments could be identified (p ≤ 0.05); imidacloprid + lambda cyhalothrin and bifenthrin caused the highest mortality of thrips with 92 and 93 % efficacy, respectively. Spinosad obtained good results, ranking as the second-best option with 90 % control efficiencies; neem extract stood out as an excellent biorational pest management alternative with 77 % control efficacy in its last evaluation. No phytotoxic effects were observed from any of the treatments on the crop. Limitations on study / implications: It is important to continue the study in the laboratory to obtain the LD50 and LD90 of the management alternatives, as well as an MRL analysis of the molecules used. Findings / conclusions: The proposed protocol evidenced the efficacy of biorational and ecological thrips control treatments in intensive horticultural systems.