The effect of fertilizers on the removal of pesticide damage in plants
The second half of the 20th century was characterized by rapid technical progress, which, on the one hand, contributed to a sharp increase in labor productivity, and on the other, to the accumulation of products polluting the habitat of plants and humans. The intensified production and application of chemical plant protection agents can be attributed to the latter factors.
When growing plants, conditions are often created where pesticides can accumulate in the soil in such quantities that they already exert a negative effect on microflora and higher plants, causing disturbances in the physiological functions of the organism. In addition, it must be taken into account that, as various studies using isotopes have shown, poisons enter plants, accumulate in agricultural products, and thereby have a negative effect on the life of humans and animals.
At the same time, the use of pesticides in agricultural production to protect plants from pests is an economically profitable method of intensifying agricultural production and is considered by scientists as a crucial condition for the development of agriculture.
Thus, along with the necessity of using pesticides in agriculture, a new task arises: to eliminate their negative influence on the vital activity of various organisms. This can be achieved in several ways: by accelerating the decomposition of poisons in the soil, increasing the resistance of agricultural plants to them, activating reparative processes in case of reversible cell damage, and reducing their accumulation in living organisms.
It is known from the literature that the negative effect of poisons decreases with a high humus content in soils and with the application of organic fertilizers. To illustrate, we present the results of one of Bogdarina's experiments (Table 1), in which the dependence between the inhibitory effect of hexachlorane on wheat seedlings and the humus content in the soil was determined.
According to research data, damage to wheat roots on different soils is caused by different doses: on sterile sand — 50 mg/m²; on overgrown sandy soil — 250—500 g/m²; on clay soil — 500 g/m²; on soil rich in humus — 2000 g/m².
From the data presented above, it is evident that on soil rich in humus, wheat roots are less subject to damage. These data primarily show the importance of microflora for the decomposition of the poison. However, these same data suggest that when detoxifying pesticides, it is also necessary to consider the possibility of their decomposition under the influence of other environmental factors.
Table 1. Effect on the height of wheat plants at different ratios of chernozem (black soil) and sand (seedling height, cm)
| Experiment Scheme | Ratio of chernozem to sand in the medium | ||||
|---|---|---|---|---|---|
| 4:0 | 3:1 | 2:2 | 2:3 | 0:4 | |
| With application of hexachlorane to the root nutrition medium | |||||
| Without poison | 7.9 | 8.6 | 9.0 | 10.5 | 10.6 |
| With application to medium | 7.8 | 5.9 | 5.2 | 3.7 | 3.7 |
| With dusting of seeds with hexachlorane before sowing | |||||
| Without dusting | 7.5 | 9.0 | 8.5 | 9.5 | 9.4 |
| With dusting of seeds | 6.9 | 6.4 | 5.2 | 1.5 | 0.0 |
As previous works show, under certain conditions, individual pesticides can decompose under the influence of physical and physicochemical factors (volatilization, leaching, thermal decomposition, decomposition under the action of solar radiation, hydrolysis, and oxidation).
However, the reduction of the toxic effect of pesticides cannot be reduced solely to their decomposition in the soil. Obviously, one must also take into account the resistance of different plant species, which is largely related to their ability for reparation and regeneration.
In previous thematic articles, we hypothesized: since physiologically active substances of humic nature significantly accelerate the synthesis of nucleic acids and protein and thereby activate reparation processes, they should also mitigate the damaging effect of agricultural poisons on plants. The stimulating effect of physiologically active substances of humic nature on microflora has been established long ago.
Thus, in our experiments, we proceeded from the premise that by using physiologically active substances of humic nature, it is possible to achieve, on the one hand, acceleration of reparation processes in damaged plants, and on the other, stimulation of microbiological activity, which should lead to the decomposition of poisons in the soil and reduce their intake into plants. The present work is dedicated to the study of these issues.
Methodology
The questions posed in this study were resolved by setting up vegetation experiments in sand and soil cultures, thanks to which it was possible to isolate the role of organic matter in the soil. The significance of the organic matter of fertilizers was differentiated by parallel application of mineral and humic fertilizers.
Experiments in sand culture were established on the Pryanishnikov mixture, where humic fertilizers were applied in the form of the preparation Adept Agro.Bio and calculated for P (Phosphorus) and N (Nitrogen) in corresponding equivalents. In soil cultures, fertilizers were applied in the same doses as in sand cultures.
Ordinary chernozem with a humus content of 4.9% was used in the experiments. Due to the fact that pesticides inhibit primarily the genetic apparatus of the cell, we considered it necessary in these experiments to grow cucumbers for seed production with subsequent testing of the obtained seed material. Since the volume of the pots allowed for only 12 kg of nutrient substrate, only one plant per pot was left for accounting for seed production.
The test crop was cucumbers. Vegetation experiments were conducted in a mesh pavilion under a polyethylene film roof. Watering was carried out with tap water at a rate of 70% of full moisture capacity for sand and soil respectively. The experiment was repeated five times. Thiophos, phthalan, and hexachlorane were taken as the investigated poisons.
The experiments were set up in two series. In the first series, we wanted to find out if the plant could restore vital activity after damage by pesticides during short-term exposure and what role physiologically active substances of humic nature might play in this case. We proceeded from the fact that the most vulnerable phase of development from the point of view of susceptibility to poisons is the seed germination phase. In this regard, to induce damage, cucumber seeds were soaked for 24 hours in poison solutions at concentrations damaging plants by 50%, which was 0.5% for phthalan and 0.02% for thiophos.
Control seeds were soaked in water. After soaking, the seeds were washed and planted to obtain seedlings on Chesnokov's mixture containing potassium humate (K) 0.005% and without it. Two weeks later, the seedlings obtained in this way were planted according to the experiment scheme into vegetation pots.
Experiments of this series were conducted in 2018 and 2019, and seeds obtained from different variants in 2018 were planted on an identical background — the full Pryanishnikov nutrient mixture in sand culture. This determined the influence of the studied factors on the first generation.
In the second series of experiments, conducted in 2019, the poison phthalan was introduced into the root nutrition medium at a rate of 2.5 mg of phthalan per 1 kg of sand and soil. These doses were taken taking into account the LD50, which was determined in laboratory experiments. Cucumber seedlings were obtained as described above, with the difference that all seeds were soaked in water. Cucumber seeds of the first reproduction were also soaked in water, and then grown for two weeks on an identical background — Chesnokov's mixture — to obtain seedlings.
Experiments of both series were accompanied by observations of growth dynamics, timing of developmental phases, and crop yield accounting, with harvesting carried out after the full ripening of the seed vessels. In the second series of experiments, the content of poisons in the soil and in plants during the vegetation period was additionally determined. The content of poisons in soil and plants was determined dynamically: phthalan — colorimetrically (by reaction with resorcinol).
Influence of soil organic matter and fertilizers on cucumber ontogenesis, decomposition of phthalan and hexachlorane in root nutrition substrates, and their intake into plants
Visual observations, as well as measurements of plant height after just 15 days, showed a large difference in the influence of poison on plant growth depending on the root nutrition medium. In sand culture, hexachlorane applied against the background of the mineral Pryanishnikov mixture caused a sharp inhibition of growth processes (Fig. 1). This difference, starting from two weeks of age, persisted until the end of vegetation.
Adding Adept Agro.Bio to the medium in quantities strictly equivalent to the previous variant significantly improved the growth of cucumbers, however, control plants (full Pryanishnikov mixture without hexachlorane) grew significantly better.
The application of hexachlorane to soil cultures, as follows from Fig. 1, affected the course of growth processes quite differently. The inhibition of plants against the background of mineral fertilizers under the influence of this poison was less sharp than in sand cultures and was traced for approximately 40 days.
Fig. 1. Influence of HCH (Hexachlorane) applied to the medium against the background of various root nutrition conditions on cucumber height:I — sand culture; II — soil culture; 1 — Pryanishnikov mixture without HCH application; 2 — HCH applied against the background of mineral Pryanishnikov mixture; 3 — HCH applied against the background of Adept Agro.Bio.
Subsequently, the growth of plants in this variant ran parallel to the control, and two weeks before harvesting even overtook it. In the variant with hexachlorane application to the soil against the background of Adept Agro.Bio, the plant growth curve was lower than the control, but only at the very beginning of development. Three-week-old plants reached the height of the control plants, and then began to overtake them. The difference persisted until the end of vegetation. Thus, Adept Agro.Bio not only removed the inhibitory effect of hexachlorane on plant growth but also stimulated it.
It should be noted that the height of plants in soil cultures in all variants was significantly greater than in sand cultures. Figure 2 illustrates the effect of phthalan on the growth of the studied plants and shows that phthalan applied to sand cultures against the background of the mineral Pryanishnikov mixture inhibits plant growth significantly less compared to hexachlorane.
The application of this poison against the background of the Pryanishnikov mixture, where P and N were given in the form of Adept Agro.Bio, did not inhibit plant growth at all, and even, starting from approximately two weeks of age, stimulated it. In soil cultures, the application of phthalan had almost no effect on plant growth regardless of the form in which fertilizers were given, and only the control variant was somewhat better.
Since the formation of ovaries is associated with fertilization, the results obtained suggest that the introduction of poisons into the soil reduces the activity of germ cells, while Adept Agro.Bio, containing physiologically active substances, stimulates them. In soil cultures, ovaries were formed in all experiment variants, although under the influence of Adept Agro.Bio their number somewhat decreased compared to the mineral control. It also decreased in the case of hexachlorane application to the soil, whereas the application of phthalan even somewhat stimulated their formation.
Fig. 2. Influence of phthalan applied to the medium against the background of various root nutrition conditions on cucumber height:I — sand culture; II — soil culture; 1 — Pryanishnikov mixture without phthalan application; 2 — phthalan applied to the medium against the background of mineral Pryanishnikov mixture; 3 — phthalan applied against the background of Adept Agro.Bio.
Table 2 presents the results of the experiment characterizing the influence of the studied factors on the dry mass weight of plants and chlorophyll content.
Table 2. Influence of agricultural poisons and nutrition conditions on the formation of dry mass and chlorophyll in leaves (2019 experiment)
| Experiment Scheme | Sand Culture | Soil Culture | |||
|---|---|---|---|---|---|
| Poison | Nutrition Background | Dry mass weight of one plant 15/07, g | Total chlorophyll content 15/07, mg % | Dry mass weight of one plant 15/07, g | Total chlorophyll content 15/07, mg % |
| 0 | Pryanishnikov mixture | 7.6 | 173 | 13.8 | 155.4 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 14.2 | 514 | 17.1 | 237.2 | |
| Phthalan 15 mg/kg | Pryanishnikov mixture | 10.0 | 218 | 16.1 | 294.3 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 11.3 | 324 | 11.9 | 388.9 | |
| Hexachlorane 2.5 mg/kg | Pryanishnikov mixture | 2.0 | 108 | 16.7 | 313.7 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 4.0 | 268 | 19.4 | 315.6 | |
These data show that under sand culture conditions, plants with hexachlorane were significantly inferior in weight to control plants; the same can be said for their chlorophyll content. Phthalan, applied under these same conditions, did not exert an inhibitory influence on plant weight. In the control without poison application, the dry mass weight of the plant with Adept Agro.Bio was almost twice as high as with the Pryanishnikov mixture. The chlorophyll content in all variants of the experiment with Adept Agro.Bio exceeded its content in variants with mineral equivalents.
In soil cultures, the effect of poisons on the formation of dry plant mass at the same age, as well as on chlorophyll formation, followed the same pattern as in sand cultures. It is important to note that both poisons in soil culture not only did not reduce the chlorophyll content in leaves but positively affected this indicator compared to the control.
Moving on to the analysis of the data in Table 3, it must first be noted that the introduction of poisons into the root nutrition medium sharply affected the percentage of fruit yield relative to the number of ovaries. Such an effect of poisons is especially noticeable with hexachlorane. In the case of its application to the medium in sand cultures against the background of the mineral Pryanishnikov mixture, it inhibited this process so much that there were no fruits at all in this variant. With Adept Agro.Bio, fruits were formed, although the fruit yield relative to the number of ovaries was the lowest in the experiment.
Phthalan affected this indicator less compared to hexachlorane, and in the variant with Adept Agro.Bio, the fruit yield relative to the control was even somewhat higher than in the mineral control without poison application. Adept Agro.Bio, applied without poison, clearly stimulated the percentage of fruit yield relative to the number of ovaries. In this same variant, the maximum weight of one seed vessel and the weight of seed from one fruit were observed.
The application of hexachlorane against the background of the mineral Pryanishnikov mixture, as already mentioned, led to a complete absence of seed production, whereas the application of this poison against the background of Adept Agro.Bio enabled some plants to form small fruits and produce a certain amount of seeds. The application of phthalan in sand cultures sharply affected the seed productivity of cucumbers, however, the weight of one seed vessel in the variant with Adept Agro.Bio was the highest in the experiment, although the percentage of seed yield is characterized by the smallest value.
Table 3. Influence of agricultural poisons and fertilizers applied during cucumber seedling planting on their seed productivity (2019 experiments)
| Experiment Scheme | Yield Data | |||||
|---|---|---|---|---|---|---|
| Poison applied to root nutrition medium (mg/kg) | Nutrition Background | % fruit yield from ovary count | Weight of one seed vessel, g/pot | Seed weight per fruit, g/pot | % seed yield | Absolute seed weight, g |
| Sand Culture | ||||||
| 0 | Pryanishnikov mixture | 26.7 | 66.2 | 1.23 | 1.84 | 14.0 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 40.0 | 93.5 | 1.69 | 1.81 | 17.2 | |
| Phthalan 2.5 mg/kg | Pryanishnikov mixture | 20.0 | 25.5 | 0.83 | 3.35 | 15.1 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 30.8 | 164.0 | 0.56 | 0.96 | 15.1 | |
| Hexachlorane 15.6 mg/kg | Pryanishnikov mixture | 0 | 0 | 0 | 0 | 0 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 14.3 | 51.4 | 0.64 | 1.24 | 10.6 | |
| Soil Culture | ||||||
| 0 | NP equivalent to Pryanishnikov mix | 30.5 | 74.8 | 1.34 | 1.80 | 16.4 |
| NP given in Adept Agro.Bio | 45.5 | 193.0 | 2.74 | 1.50 | 18.8 | |
| Phthalan 2.5 mg/kg | NP equivalent to Pryanishnikov mix | 33.3 | 87.3 | 1.78 | 1.75 | 15.8 |
| NP given in Adept Agro.Bio | 37.5 | 121.7 | 1.55 | 1.27 | 15.8 | |
| Hexachlorane 15.6 mg/kg | NP equivalent to Pryanishnikov mix | 17.7 | 64.8 | 0.87 | 1.34 | 12.4 |
| NP given in Adept Agro.Bio | 23.1 | 107.3 | 1.47 | 1.37 | 16.3 | |
This suggests that Adept Agro.Bio promotes the growth of fruit flesh more than seeds. The highest percentage of seed yield was in the variant where phthalan was applied against the background of the full Pryanishnikov mixture, however, in this case, the weight of the seed vessel was minimal, which suggests inhibition of growth processes per se by phthalan. The absolute seed weight changed less than the seed yield indicator, however, the effect of hexachlorane was clear.
In soil cultures, the influence of poisons and fertilizers on seed production output was less sharp compared to sand culture. In this experiment, there was no case where the plant did not form fruits regardless of whether poison was applied or not, and what fertilizer was added to the pot. However, the weight of seed vessels and seeds from one fruit varied significantly depending on the conditions created by the root medium.
As in the experiment in sand cultures, the application of hexachlorane to the soil against the background of mineral fertilizers substantially reduced seed production formation. In the case of Adept Agro.Bio application, fruit growth and seed yield normalized. The application of phthalan against the background of mineral fertilizers somewhat increased the weight of seeds from one fruit and did not affect their yield.
This same poison against the background of Adept Agro.Bio resulted in a decrease in the percentage of seed yield compared to the mineral control, although the weight of seeds from one fruit was practically equal, and the fruit weight as a whole exceeded the mineral control. The maximum fruit and seed weight was obtained in the variant of applying Adept Agro.Bio as a source of nitrogen and phosphorus to the soil. However, the percentage of seed yield in this variant was significantly lower than with mineral fertilizers. Under the influence of Adept Agro.Bio, i.e., a fertilizer containing physiologically active forms of humates, the percentage of seed yield in tomatoes decreases under the condition of an increase in the total fruit yield.
Fig. 3. Dynamics of poison decomposition in the root nutrition substrate:I — HCH (Hexachlorane); II — Phthalan: 1 — sand, full Pryanishnikov mixture; 2 — sand, Pryanishnikov mixture where N and P are given in Adept Agro.Bio; 3 — soil, mineral fertilizers equivalent to Adept Agro.Bio; 4 — soil, Adept Agro.Bio.
Let us now consider the influence of various conditions in the root nutrition medium on the decomposition of poisons (Fig. 3). It follows from this figure that the decomposition of phthalan proceeded quite intensively and by the end of vegetation the amount of poisons dropped to acceptable levels. However, both the substrate and the fertilizers left their mark on this process.
The decomposition of phthalan proceeded most rapidly in soil fertilized with Adept Agro.Bio, and most slowly in sand with the application of the mineral Pryanishnikov mixture. The application of Adept Agro.Bio to sand resulted in poison decomposition at the same rate as when applied to soil fertilized with mineral fertilizers.
As for the course of this process over time, the decomposition of phthalan proceeded quite actively until approximately 45 days, and then slowed down. Hexachlorane, introduced into the root nutrition medium, also decomposed in the soil, and over time it followed the same pattern as the decomposition of phthalan.
Regarding the influence of root substrates and fertilizers, the same general pattern as for phthalan is preserved here. However, the gap in the action of these factors during the decomposition of hexachlorane was greater than with phthalan. Namely: the application of Adept Agro.Bio to the soil ensured the complete decomposition of the poison by the 70th day, whereas in all other variants the decomposition was not completed until the end of vegetation.
The amount of hexachlorane undecomposed in the substrate in sand culture under the variant "full Pryanishnikov mixture" throughout the entire vegetation period was always greater than in all other variants. Thus, based on these data, it can be concluded that the rate of poison decomposition is influenced by both the nature of the substrate and the application of fertilizers. Organic matter of the soil, as well as its application with fertilizer, contributed to better decomposition of the studied agricultural poisons.
The root nutrition medium and fertilizers also influence the accumulation of poisons in the plant. From Table 4, which provides similar data on the content of poisons in different plant organs, one can conclude primarily that in sand cultures plants accumulate more poison than in soil cultures.
Table 4. Influence of fertilizers on the accumulation of poisons in plants (2019 experiment)
| Experiment Scheme | Concentration of poison and gamma-isomers per 100 g of absolute dry substance | |||
|---|---|---|---|---|
| Phthalan | Hexachlorane | |||
| Min. fert. | Adept Agro.Bio | Min. fert. | Adept Agro.Bio | |
| Soil Culture | ||||
| Seedlings after 30 days | ||||
| Roots | 17.2 | 5.8 | 12.948 | 1.60 |
| Stems | 4.8 | 2.1 | traces | traces |
| Leaves | 2.1 | 0.32 | 2.74 | 0.95 |
| Fruits | ||||
| Peel | 1.127 | 0.419 | 2.4 | 0.54 |
| Pulp | 0.695 | 0.447 | 1.8 | 0.49 |
| Sand Culture | ||||
| Seedlings after 30 days | ||||
| Roots | 19.2 | 7.1 | no data | 2.82 |
| Stems | 6.9 | 4.4 | — | 2.4 |
| Leaves | 2.8 | 0.3 | — | 1.4 |
| Fruits | ||||
| Peel | — | 0.764 | — | 1.9 |
| Pulp | — | 0.522 | — | 1.33 |
The application of Adept Agro.Bio to the nutrient medium contributed to reducing the accumulation of both phthalan and hexachlorane in plants. The poison accumulates most in the roots, then in the stems, and least of all was found in the leaves.
Regarding the content of phthalan and hexachlorane in the fruits, unfortunately, it was found there in all experiment variants. The application of organic fertilizers and growing cucumbers on soil fertilized with Adept Agro.Bio allowed reducing the accumulation of both phthalan and hexachlorane in the fruits.
Such an effect of soil organic matter and fertilizers is most easily linked to their influence on the course of poison decomposition in the soil. At the same time, it can be hypothesized that in this case, there is lower permeability of root cells for poisons, however, we have no direct evidence for such a conclusion. This requires special experiments investigating the permeability of cell membranes in plants for different poisons. The assumption that decomposition of poisons occurs due to enzymatic processes within the plant itself is also not excluded.
Influence of soil organic matter and fertilizers on the ontogenesis of cucumbers damaged in the seed germination phase by phthalan and thiophos
Plants can be subjected to the damaging effect of poisons used in agriculture for pest control when they are applied to the soil and thus act throughout the entire vegetation period, and during short-term exposure when seeds are treated with them. The first case was discussed above. Now let us consider the second possibility.
Above, when describing the methodology, it was already noted that in order to find out whether organic substances of the soil and fertilizers, and primarily their physiologically active forms, would restore the vital activity of plants in ontogenesis after damage by pesticides in the seed germination phase, experiments were conducted with soaking cucumber seeds (see methodology) in poison solutions with subsequent transplantation of plants to variously fertilized media.
Fig. 4 illustrates the growth of plants after soaking seeds in a phthalan solution, Fig. 5 — in a thiophos solution according to 2019 experiments. It follows from the figures that regardless of what the seeds were soaked in, the height of plants during the vegetation period in soil cultures was always higher than in sand cultures.
When growing cucumbers in sand against the background of the full Pryanishnikov mixture, the height of plants damaged and undamaged by phthalan was initially close, and only by the end of vegetation did the inhibitory influence of phthalan become more noticeable.
When growing cucumbers in soil cultures, plants did not have reliable differences in growth in all variants until the beginning of July. By the end of vegetation, the height of plants on the mineral background differed noticeably from the background with the preparation Adept Agro.Bio. It should also be noted that the growth of plants on the mineral background practically ceased in mid-July, whereas on humic fertilizers plants grew until the foliage turned yellow.
Fig. 4. Influence of physiologically active humic substances on the growth of cucumbers whose seeds were damaged by phthalan (2019 experiment):I — sand culture; II — soil culture; 1 — control, medium with mineral fertilizers, seeds soaked in water; 2 — medium with mineral fertilizers, seeds soaked in phthalan; 3 — medium with Adept Agro.Bio, seeds soaked in phthalan.
As follows from Fig. 5, the influence of soaking seeds in thiophos affected plant growth in approximately the same way as soaking in phthalan. In the 2018 experiments, the character of cucumber growth did not fundamentally differ from the 2019 picture, so the corresponding graphs are not presented.
Fig. 5. Influence of physiologically active humic substances on the growth of cucumbers whose seeds were damaged by thiophos (2019 experiment):I — sand culture: II — soil culture; 1 — control, medium with mineral fertilizers, seeds soaked in water; 2 — medium with mineral fertilizers, seeds soaked in thiophos.
Despite the fact that no particular difference in plant height by variants in the 2019 experiment was detected on July 15, the difference in dry mass accumulation and chlorophyll content (Table 5) on the same date, i.e., at the height of flowering, was significant in sand cultures and less noticeable in soil cultures.
Control plants, seeds of which were soaked in water and grown on a background with Adept Agro.Bio application, differed positively in these indicators from variants with mineral fertilizers. Soaking seeds in both phthalan and thiophos significantly inhibited the formation of dry plant mass at the height of flowering provided they were grown on the Pryanishnikov nutrient mixture, whereas Adept Agro.Bio completely normalized the process of dry matter formation.
Table 5. Influence of soil organic matter and fertilizers on the accumulation of dry matter and chlorophyll in plants (2019 experiment)
| Experiment Scheme | Dry mass weight of one plant at height of flowering 15.06.19, g | Total chlorophyll content on 15.07.19, mg % | |
|---|---|---|---|
| Seed soaking medium | Plant growing medium | ||
| Sand Culture | |||
| Water (Control) | Full Pryanishnikov mixture | 7.6 | 173.8 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 14.2 | 514.9 | |
| Phthalan 0.5% | Pryanishnikov mixture | 3.3 | n/a |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 16.2 | n/a | |
| Thiophos 0.2% | Pryanishnikov mixture | 6.5 | 128.8 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 14.2 | 305.7 | |
| Soil Culture | |||
| Water (Control) | NP equiv. to Pryanishnikov mix | 13.8 | 155.4 |
| NP given in Adept Agro.Bio | 17.10 | 237.2 | |
| Phthalan 0.5% | NP equiv. to Pryanishnikov mix | 14.9 | 191.5 |
| NP given in Adept Agro.Bio | 14.0 | 287.2 | |
| Thiophos 0.02% | NP equiv. to Pryanishnikov mix | 15.5 | 168.2 |
| NP given in Adept Agro.Bio | 15.8 | 257.6 | |
In soil cultures, obviously, the humic substances of the soil itself were the normalizing factor in the indicated plan, since the influence of humic fertilizers in this case did not differ from the influence of mineral ones. From this same table, it follows that humic fertilizers stimulated the process of chlorophyll formation. As for the influence of treating plants with poisons in the initial phase of their development, by the time of flowering, it did not affect chlorophyll content sharply.
Table 6 illustrates the influence of the studied factors on fruiting and seed formation over two years of experiments. First of all, it is necessary to note that although the general patterns of action of the studied poisons and fertilizers in both years are fundamentally identical, the degree of manifestation of these factors varies by year.
For example, in 2018, soaking seeds in a solution of phthalan and thiophos, when transplanting seedlings into sand cultures on the full Pryanishnikov mixture, sharply inhibited the weight of the seed vessel. The influence of poisons on seed formation was even more severe, leading to the fact that in the variant with phthalan, all fruits on all repetitions of this variant turned out to be parthenocarpic, and with thiophos gave an insignificant yield.
Growing plants damaged by both poisons on a medium with humophos reliably normalized the seed productivity of cucumbers. In 2019, the inhibitory effect of poisons on the formation of seed vessels and seeds under sand culture conditions was much less noticeable.
Humic fertilizers, strictly balanced in content of mineral nutrient elements with the Pryanishnikov mixture, clearly stimulated both the growth of the seed vessel and seed formation. The action of this fertilizer on cucumbers damaged at the beginning of development by phthalan manifested in the fact that they completely normalized the formation of seed production, even slightly increasing the yield compared to the undamaged control. However, it is not yet possible to conclude on synergy in this case, since the increase against the control with Adept Agro.Bio application, but without poison damage, is within the limits of possible experimental error.
The action of humic fertilizers when plants were damaged by thiophos was less sharp compared to the previous variant. And yet, the normalizing effect of these fertilizers in this variant is also beyond doubt, since both the weight of the seed vessel and the weight of seeds correspond to their weight in the variant with the full Pryanishnikov mixture, but without poison exposure. As for the influence of all studied variants on the absolute weight of seeds, it was barely noticeable.
The results of the experiments show that in soil cultures, the inhibitory effect of phthalan manifested less than in sand cultures, while the action of thiophos was quite noticeable. The normalizing influence of humic fertilizers in soil cultures appeared in both years of experiments, but in 2019 the relative degree of their impact was higher. The application of Adept Agro.Bio under plants undamaged by poisons gave a significant increase in both fruit and seed weight, however, the percentage of their yield was lower than in the control variant fertilized with mineral fertilizers.
The obtained data once again confirm previously obtained data that physiologically active substances stimulate the growth of the pericarp more intensively compared to the seeds, due to which the percentage of seed yield somewhat decreases, although their absolute weight and yield not only do not decrease but even increase.
Table 6. Influence of soil organic matter and fertilizers on the seed productivity of cucumbers damaged by poisons during seed germination (according to 2018—2019 experiments)
| Experiment Scheme | Average weight of one seed vessel per pot | Average weight of seeds per pot | Absolute seed weight | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Seed soaking medium | Plant growing medium | 2018 | 2019 | 2018 | 2019 | 2018 | 2019 | ||||
| g | % | g | % | g | % | g | % | ||||
| Sand Culture | |||||||||||
| Water | Pryanishnikov mixture | 109.8 | 100 | 66.7 | 100 | 1.98 | 100 | 1.23 | 100 | 13.8 | 15.0 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | n/a | — | 93.5 | 138.2 | n/a | — | 1.69 | 137.5 | n/a | 15.0 | |
| Phthalan 0.5% | Pryanishnikov mixture | 16.1 | 14.7 | 43.2 | 64.7 | p.c. | — | 1.07 | 87.0 | p.c. | 15.3 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 130.5 | 119.0 | 103.0 | 152.2 | 1.74 | 87.8 | 1.78 | 145.0 | 18.6 | 15.1 | |
| Thiophos 0.02% | Pryanishnikov mixture | 19.7 | 18.0 | 48.5 | 72.7 | 0.16 | 8.0 | 1.05 | 85.4 | 14.4 | 12.0 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 112.3 | 110.8 | 76.8 | 115.2 | 2.01 | 101.5 | 1.31 | 106.5 | 14.1 | 18.6 | |
| Soil Culture | |||||||||||
| Water | NP equiv. to Pryanishnikov mix | 136.9 | 100 | 74.7 | 100 | 2.01 | 100 | 1.34 | 100 | 14.3 | 16.4 |
| NP given in Adept Agro.Bio | - | - | 193.0 | 258.0 | - | - | 2.74 | 204.2 | - | 18.8 | |
| Phthalan 0.5% | NP equiv. to Pryanishnikov mix | 121.7 | 88.9 | 59.7 | 79.8 | 1.63 | 77.6 | 1.06 | 76.8 | 14.3 | 15.3 |
| NP given in Adept Agro.Bio | 158.0 | 115.2 | 117.2 | 156.8 | 2.27 | 108.2 | 2.60 | 194.0 | 16.9 | 17.1 | |
| Thiophos 0.02% | NP equiv. to Pryanishnikov mix | 116.5 | 85.2 | 42.3 | 56.6 | 1.68 | 80.0 | 0.56 | 41.7 | 12.3 | 12.9 |
| NP given in Adept Agro.Bio | 148.5 | 108.5 | 113.0 | 151.0 | 2.46 | 117.2 | 2.03 | 151.5 | 13.1 | 35.6 | |
Our vegetation experiments were conducted in a mesh pavilion, so the temperature and air humidity were the same as in the open environment. Therefore, the difference in the strength of the effect of the studied factors by year cannot be explained without linking it to the specific meteorological conditions of both years. We present these data in Table 7.
Table 7. Weather and climate conditions in the vegetation pavilion for May—July 2018/2019
| Indicator | Year | May (decades) | June (decades) | July (decades) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 | ||
| Air temperature, °C | 2018 | 15.0 | 23.7 | 28.4 | 28.8 | 24.6 | 22.9 | 23.4 | 29.0 | 31.1 |
| 2019 | 11.9 | 19.1 | 22.7 | 20.8 | 25.3 | 22.8 | 20.1 | 26.2 | 29.2 | |
| Relative air humidity, % | 2018 | 80.4 | 46.8 | 63.1 | 43.7 | 66.1 | 73.7 | 52.6 | 44.4 | 56.4 |
| 2019 | 69.6 | 52.2 | 69.5 | 59.5 | 63.7 | 63.2 | 74.9 | 56.5 | 42.7 | |
| Number of hours of sunshine | 2018 | 0.1 | 12.7 | 9.6 | 10.7 | 8.6 | 6.9 | 6.8 | 10.6 | 9.6 |
| 2019 | 4.7 | 9.3 | 10.3 | 9.3 | 11.8 | 7.7 | 4.2 | 10.2 | 11.3 | |
In order to study the influence of the damaging effect of poisons on progeny, as mentioned in the methodology description, an experiment was established in 2019 in which seeds obtained in 2018 from all variants were planted on a common background — the full Pryanishnikov mixture in sand cultures.
Visual observations already showed that the growing conditions of the maternal plants did not have a particular influence on the growth of the first-generation plants. However, seedlings in the variant with soaking maternal seeds in thiophos and growing them on a mineral background in sand cultures lagged in weight and dry matter formation. Yield data for this experiment are presented in Table 8.
Table 8. Influence of soil organic matter and fertilizers on the seed productivity of first-generation cucumbers, whose parental forms were damaged by poisons.
| Experiment Scheme | Yield data of 1st generation from parental forms | |||||
|---|---|---|---|---|---|---|
| Seed soaking medium | Plant growing medium | Average seed vessel weight per pot | Average seed weight per pot | Absolute seed weight | ||
| g | % | g | % | |||
| Maternal plants were grown in sand culture | ||||||
| Water | Pryanishnikov mixture | 85.5 | 100.0 | 1.65 | 100.0 | 14.5 |
| Phthalan 0.5% | Pryanishnikov mixture | n/a because fruits in 2018 were p.c. (parthenocarpic) | ||||
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 113.5 | 132.6 | 1.97 | 119.4 | 15.8 | |
| Thiophos 0.02% | Pryanishnikov mixture | 53.8 | 62.9 | 0.82 | 50.0 | 12.0 |
| Pryanishnikov mixture, where NP are given in Adept Agro.Bio | 64.5 | 75.44 | 1.03 | 68.5 | 14.6 | |
| Maternal plants were grown in soil culture | ||||||
| Water | NP equiv. to Pryanishnikov mix | 133.5 | 100 | 2.03 | 100 | 16.4 |
| Phthalan 0.5% | NP equiv. to Pryanishnikov mix | 129.3 | 95.46 | 2.26 | 111.4 | 17.1 |
| NP given in Adept Agro.Bio | 133.5 | 102.2 | 2.35 | 115.8 | 17.1 | |
| Thiophos 0.02% | NP equiv. to Pryanishnikov mix | 123.4 | 91.9 | 1.83 | 90.2 | 15.0 |
| NP given in Adept Agro.Bio | 132.7 | 99.4 | 1.97 | 97.0 | 16.0 | |
They show that first-generation plants grown from seeds obtained in sand culture under the Adept Agro.Bio variant, but which had phthalan damage, produced completely normal seed output, whereas with thiophos damage to maternal forms, the formation of seeds and seed vessels in first-generation plants was clearly inhibited. The advantage of Adept Agro.Bio in this regard was almost within the margin of experimental error.
No substantial difference was noticed in the yield of seed vessels and seeds of plants grown in soil culture. In this case, likely, the organic matter of the soil removed the toxicosis in the maternal plants and the seeds of these plants turned out to be qualitatively close.
On the whole, all the presented experimental material shows that the organic matter of the soil and fertilizers has a significant influence on the mitigation of damage to plants caused by agricultural poisons. This gives the right to assume that humic fertilizers can become an important factor in the fight against pollution of the plant habitat and its improvement.
However, the presented material does not yet allow making any recommendations in this aspect, but indicates the need for deeper and broader study of this issue.