Dr. Plamen Marinov-Serafimov, Institute of Forage Crops – Pleven
The aim of the study is: To establish and compare the herbicidal efficacy of commercial formulations and their information spectral copies (IC), by water.
MATERIAL AND METHODS
Experiments were carried out under laboratory conditions in pots with soil in four replicates. The treatment was carried out block by variant with a pulsation sprayer (Akku-Wasserspruher) with a flat nozzle. The commercial products with herbicidal effect were applied in the registered dose by the manufacturing companies for Polish conditions (ml/da), as well as their informative spectral copies (IC) through a working solution in water, as for all variants in the experiment the application dose and the amount of the working solution are recalculated according to the volume of the cultivation vessel. To conduct the experiment, plant species (test plants) were selected – lettuce (Lactuca sativa L.) and alfalfa (Medicago sativa L.), which have proven high sensitivity to herbicide formulations and are non-selective to them. The treatment was performed block by variant.
The following herbicide formulations were included in the experiment:
Beloukha (680 g/l nonanoic (pelargonic) acid); Emulsion concentrate – EC; Application dose: 160 ml/day. Total contact herbicide (desiccant) of plant origin. Pelargonic acid is extracted from rapeseed oil only by physical methods (temperature, pressure). Due to its unique mechanism of action, weeds treated with Beloukha die in a few hours (following the recommendations for use). Beluukha is harmless to the environment, once it gets into the soil it breaks down into CO2 and H2O.
Ecopart turbo (6.25 g/l pyraflufen – ethyl); Emulsion concentrate – EC; Application dose: 80 ml/day. Total contact herbicide (desiccant) with active substance pyraflufen-ethyl. Destroys all green parts of plants. It blocks the synthesis of chlorophyll in the green parts of the plant. It does not accumulate in the environment and is not toxic to bees and earthworms.
Zi – End Active in: 14% water-soluble Zinc (Zn); Formulation: Eco fertilizer; Dosage: 15% solution. It is used at the end of the growing season of crops, as a desiccant, before harvesting.
Laudis OD [44 g/l tembotrione; 22 g/l isoxadifen-ethyl (antidote); Oil dispersion (OD); Dose of administered 200 ml/da. Vegetative, broad-spectrum, systemic herbicide containing the active substance tembotrione from the chemical group of triketones. Controls broadleaf and wheat weeds. It is taken up by the leaves and transported to the growing parts of the plant. Immediately after application, treated weeds stop growing and after 3 to 5 days severe bleaching and discoloration of leaves followed by necrosis is observed. The weed vegetation dies in a period of up to two weeks.
Onyx (600 g/l pyridate); Emulsion concentrate – EC; Application dose: 150 ml/day. Contact vegetation herbicide for the control of broadleaf weeds. It is absorbed by the leaves of weeds. Weed growth stops immediately and under optimal conditions the visible effect is 3-4 days after treatment in the form of necrotic spots starting from the edge of the leaves.
In the case of commercial products with a herbicidal effect for vegetative application and their information spectral copies (IC), the test plants were used:
30% of the commercial product (herbicide) was added to the information spectral copies (IC) of the products with herbicidal effect included in the study for each one of them, according to the dose registered by the manufacturer.
The treatment was carried out in the cotyledon phase of the lettuce and alfalfa, and the phytotoxic effect of the herbicides included in the experiment was calculated according to the logarithmic nine-point scale of the EWRS on 1, 3, 5, 7 and 14 days after the treatment, taking pictures with a camera and digital microscopic camera.
The plants were grown under a photoperiod of 13h day and 11h night with a photo-solar lamp to imitate sunlight.
RESULTS AND DISCUSSION
The treatment of the test plants lettuce and alfalfa with the herbicide Beloukha (680 g/l nonanoic (pelargonic) acid) (a total contact herbicide (desiccant) of plant origin) at a dose of 160 ml/da and its information spectral copy (IC) in the cotyledon phase cultures, an equivalent, rapid initial desiccation effect was found (Table 1 and 2). No visual differences in the desiccation effect were found in the two test crops, both when applying the herbicide formulation and when treating the crop with its information spectral copy (IC). On the first day after the treatment (1 DAT), visible chrotic changes were observed on the plants, which on the third and fifth day after the treatment turned into necrosis and death of the plants. The results obtained when determining visual phytotoxicity according to the logarithmic scale of the EWRS are also similar (Table 3). For all treatments, a score of 9 was determined, that is, on the first day after the treatment, a lethal effect of the cultures included in the study was established.
The biological impact of pyraflufen-ethyl on the plant organism is expressed in blocking the synthesis of chlorophyll in plants, as a result of which all green parts of the plants die. Its application, in the form of the commercial product Ecopart turbo at a dose of 80 ml/da, as well as its information spectral copy (IC) caused an equivalent desiccation effect in lettuce (Table 4). From a visual inspection, it is clear that on the first day, after the treatment, a moderate-strong phytotoxic effect of 7.5 points on the EWRS scale (Table 3) was established, expressed by chlorotic changes, passing into necrosis on the leaf surface, regardless of the used working solution – herbicide or its information spectral copy (IC). By extending the period of vegetation until the third day after treatment, a lethal effect of the test-plant lettuce was established (score 9). Regardless of the observed visible visual symptomatic damages on the lettuce, when observing with a digital electron microscope, differences were found depending on the application of the working solutions – from the commercial product (Ecopart Turbo) compared to its information spectral copy (IC).
It is evident from Table 4 that on the first day of the treatment, the application of the working solution from the commercial product Ecopart Turbo has a relatively weaker phytotoxic effect on the leaf petura of the lettuce, the same structure is unchanged in the turgor of the cotyledons and colored green, while with the use of information spectral copy (IC) the same has a changed structure – partially dehydrated, wrinkled with uneven areas on the periphery of the leaf, which has a changed color, which determines a strong initial effect of information spectral copy (IC) compared to the commercial herbicide solution. Extending the period to the third day, after the treatment in the variant treated with the commercial product Ecopart Turbo, a rapid initial effect of desiccation (necrosis on the leaf mass) was found on the test plant, while a weak retention effect was found in its information spectral copy (IC). of a slower transition of phytotoxic chlorophyll changes into necrosis. Regardless of the insignificant differences in the observed desiccation effect (found only when observed with a digital microscope), it can be summarized that on the fifth day of treatment, an equivalent desiccation effect was established in the salad, regardless of the application of the chemical product Ecopart Turbo and/or its information spectral copy (IC).
When treating alfalfa, visible visual differences were found in the initial phytotoxic (desiccation) effect of the commercial product – Ecopart turbo compared to its information spectral copy (IC) (Table 5). When applying the commercial product Ecopart turbo, the desiccation effect on alfalfa occurs until the seventh day, after treatment, that is, with the extension of the vegetation period of the crop, the phytotoxicity increases smoothly from 3 to 9 points (Table 3), while when applying its informative spectral copy ( IC), a proven desiccation effect is reported after the seventh day of treatment – score 5. Regardless of the type of working solution used – from the commercial product or its information spectral copy (IC) on the fourteenth day, after treatment an equivalent lethal effect is established (score 9 ) and desiccation of the culture.
The offer of the eco-fertilizer Zi-End [14% water-soluble Zinc (Zn)], as a desiccant, has a rapid initial effect on lettuce, with no apparent significant differences depending on the application of the chemical formulation or its information spectral copy (IC) ( Table 6).
When applying the eco-fertilizer Zi-End and its information spectral copy (IC) to alfalfa, significant visible differences were found regarding the initial impact regarding the desiccation effect on the crop (Table 7). The commercial formulation Zi-End, applied in a dose of 15% working solution, causes a rapid desiccation effect in the third-fifth day, after treatment (6-8 points), while when applying its information spectral copy (IC) a floating and uneven desiccation effect on alfalfa aboveground biomass, although the visually determined phytotoxicity scores, according to the EWRS logarithmic scale, were close (Table 3). From the electronic pictures taken with a digital microscope, it is clear that in the period three to seven days, after treatment, the desiccation effect in alfalfa is unevenly manifested, which can be explained by the way of impact of Zn, which passively enters the plant organism, and its biological impact is based on reducing the intercellular resistance in the surface layer of the structural formations on the leaves, associated with the thickened epidermal cells covered with a protective layer (cuticle) and the presence of a wax coating in the culture. According to Ni et al. (2012) cuticular waxes on alfalfa leaves were dominated by primary alcohols (41.7 – 54.2%), alkanes (13.2-26.9%), terpenes (17.5 -28.9%), aldehydes (1.4-3.4%) and other unidentified substances (4.5-18.4%). Regardless of the unevenly expressed symptomatic damage observed on the vegetative parts of alfalfa (cotyledons, leaves and stems), after the application of an information spectral copy (IC) of the eco-fertilizer Zi-End for fourteen days, an equivalent desiccation lethal effect was established after treatment (score 9) , both when applying the commercial eco tor Zi-End and when using its information spectral copy (IC).
The broad-spectrum herbicide Laudis used in agricultural practice for the complex fight against broad-leaved and wheat weeds in cereal crops, as well as its informative spectral copy (IC) applied to lettuce, had a lethal effect (score 9) on the development of the test plant until the seventh day after treatment.
The application of the information spectral copy (IC) of Laudis herbicide to lettuce has a faster initial effect compared to the standard working solution of the commercial product used. The lethal effect (efficacy) of the IC application of the herbicide was reported significantly earlier, on the fifth day, after the lettuce treatment, therefore, the IC of the commercial product Laudis had a similar faster initial chemical action (efficacy) compared to the standard working solution from the commercial product, despite the fact that the active substance of the herbicide in the working solution of the information spectral copy (IC) is insignificant – 30% (2.64 g/l), in comparison with the same for the commercial working solution of the product – 8.8 g/l
The herbicidal efficacy of the standard working solution of Laudis (200 ml/da) for field conditions and its informative spectral copy (IC) included in the study had an equivalent phytotoxic effect on alfalfa, expressed in leaf discoloration chlorosis (albism), which until the twenty-first day, after treatment it turns into necrosis. From the results presented in Table 3, it is clear that regardless of the type of applied working solution of Laudis 200 ml/da or its informative spectral copy (IC), similar phytotoxicity scores are reported, which increase from 1 (no symptomatic damage) up to 9 points (lethal effect) with an extension of the alfalfa vegetation period. No differences were found in the biological impact of the conventional Laudis working solution and its used information spectral copy (IC) (Table 9). On the fifth day, after the treatment of the alfalfa, no uniform phytotoxic changes were found – the newly appeared primodial (non-true) leaves of the alfalfa for all variants of the experiment had clearly expressed chlorotic changes (albism), characteristic of the phytotoxic effect of the active substance tembotrion, appearing in sensitive plants, after application of herbicides from the group of triketones. Visually observed phytotoxic symptomatic damages on alfalfa are intensified, which in the period from the fifth to the fourteenth day, after the treatment, are intensified, and no significant visual differences are found in the established phytotoxic effect of the commercial herbicide used and its information spectral copy (IC) which is in direct connection with the biochemical impact of the indirect herbicidal effect of tembotrione (belonging to the group of triketones), as an ALS inhibitor, determining the blocking of carotenoid synthesis, as a result of which sensitive plants die under the influence of ultraviolet light. On the twenty-first day, after the treatment, the established chlorotic (albism) changes progressed to necrosis and death of the alfalfa, both with the commercial solution of Laudis and with the application of its information spectral copy (IC).
The contact vegetation herbicide Onyx (600 g/l pyridate) used in the control of broadleaf weeds and its information spectral copy (IC) included in the study showed the same and equivalent phytotoxic effect when applied them on salad (Tables 3 and 10). From the analysis results presented in Tables 3 and 10, it is evident that the information spectral copy (IC) used of the herbicide commercial formulation Onyx does not differ significantly in the mechanism of biological action and the observed visual symptomatic damage on the lettuce compared to its information spectral copy (IC). In all variants of the experiment, depending on the effect of the working solutions used, their phytotoxic effect (efficacy) varies from weak to insignificant (point 2) on the third day, after the treatment, to lethal (point 9) (100 efficacy) by the fifth – seventh day , after their application.
The application of a working solution of the commercial product Onyx and its information spectral copy (IC) to alfalfa showed significant differences in the initial phytotoxic effect on the crop (Table 11). From insignificant (score 1) to relatively weak (score 2) are the observed visible phytotoxic changes on the test plants – first-third day, after treatment, which can be explained by the biological effect of the active substance pyridate, which is the only representative of the chemical group phenyl-pyridazine with a proven inhibitory effect on the photosynthesis of sensitive plants, through the D1 quinone. Regardless of its lipophilic characteristics, pyridate is absorbed relatively faster by plants and requires time to bind to photosystem II to terminate the transport of electrons in plant photosynthesis, which also accounts for the relatively weak initial effect on the test plant alfalfa.
Regardless, the treatment of alfalfa with the information spectral copy (IC) of the herbicide showed a relatively faster initial effect (bol 6) on the fifth day, while, compared to the applied working solution of the commercial product Onyx (score 7). Regardless of the observed insignificant differences on the efficacy of the working solutions included in the study, on the seventh day, after the treatment of alfalfa, both with the working solution of the commercial product Onyx and with its informative copy, death of the test plant was found (score 9).
Following the applied experimental approach, an in vitro (vessel) test was developed to establish and compare the equivalence of the biological impact of commercial products with herbicidal effect and their information spectral copies (IC), in water of the test plant lettuce (Lactuca sativa L.) cultivar ‘Iceberg’ and alfalfa (Medicago sativa L.) variety “Dara”.
The use of both types – lettuce (Lactuca sativa L.) and alfalfa (Medicago sativa L.) when carrying out vascular experiments in laboratory (controlled) conditions, guarantees rapid initial development of the test plants, the possibility of establishing species differences, in relation to the biological effect of the impact of commercial products with a herbicide effect and their information spectral copies (IC) , which is a prerequisite for proving their bioequivalence of impact and the possibility of interchangeability when used in plant protection practices.
The recommended working doses for field conditions of the commercial products with herbicidal effect included in the study () and their informative spectral copies (IC), cause bioequivalent phytotoxic and lethal effect of the sensitive included in the study types of lettuce (Lactuca sativa L.) and alfalfa (Medicago sativa L.), which is a prerequisite for reliable experimental results.
A clear bioequivalent (herbicidal) effect with a desiccation effect is established when applying the herbicides Beluka, Ecopart Turbo and the eco-fertilizer Zi-End with a proven contact desiccation effect and their informative spectral copies ( IC) the test plants lettuce (Lactuca sativa L.) and alfalfa (Medicago sativa L.)
The application of the commercial herbicides Laudis (for alfalfa) and Onyx (for lettuce) as well as their information spectral copies (IC) cause equivalent biological effects, such as the observed phytotoxic symptomatology by test- plants does not differ significantly in the caused visual symptomatic damage (i.e. phytotoxicity) according to the mechanism of action of the active substances on the test plants included in the study.
The application of the information spectral copies (IC) of the herbicides Laudis (for lettuce) and Onyx (for alfalfa) have an equivalent phytotoxic effect on the test plants with the difference that the impact of the information spectral copy (IC) has a faster initial effect (efficacy) compared to standard working solutions from commercial products, despite the fact that the active substance of herbicides in the working solution of information spectral copy (IC) is significantly less (constitutes 30 % of the applied dose), compared to the same in commercial working solutions of the herbicides (applied in standard doses registered by the manufacturing companies).
The inclusion of information spectral copies (IC) of herbicides widely used in agricultural practice as a means of fighting against weeds is a prerequisite for a lower anthropogenic load and protection from chemical pollution (accumulation of chemical substances in the arable land and their migration in the groundwater) of the agrophytocenoses. The established efficacy of the information spectral copies (IC) included in the study is probably due to their rapid inclusion in the process of the metabolism of the test plants, determined by surface tension, capillarity and intermolecular cohesion of water, contributing to its unimpeded absorption and active entry into plant organisms in the process of the exchange of substances in cultivated plants.
Ni, Y., Y. Guo,L. Han, H. Tang, M.Conyers, 2012. Leaf cuticular waxes and physiological parameters in alfalfa leaves as influenced by drought. Photosynthetica, 50(3): 458-466.