The effect of humate on plant physiology. Relieving plant stress caused by insecticides and fungicides
The objective of this work was to establish the possibility of relieving the inhibitory effect of insectofungicides on various agricultural plants using physiologically active substances.
It was conducted using the method of soaking seeds of agricultural crops in solutions of poisons with subsequent transplantation onto physiologically active substances. This method of pesticide exposure to plants is most convenient in this case because, firstly, the seed germination phase is physiologically the most vulnerable to the action of poisons in plant ontogenesis and, secondly, the brief exposure of plants to poisons allows excluding the issue of poison persistence during the experiment, which is of great importance in experiments with the constant presence of poisons, for example, in a root nutrition medium.
By transplanting seeds to a medium with physiologically active substances after soaking in poisons, a separation of the action of poisons and humic substances in time is achieved. Seeds of test crops were soaked in insectofungicide solutions for 24 hours. Then, after thorough washing with water, one part of the seeds was planted on a mineral nutrient medium, and the other on the same medium but containing 0.005% potassium humate. The experiment was evaluated after 12 days. The height of the above-ground mass, root length, and weight were recorded.
Determination of ID50 for various poisons and the influence of physiologically active humus substances on this indicator
Determining the ID50 of poisons on plant tests is complicated by the fact that all three of the above indicators—root length, height of above-ground mass, and seedling weight—react differently to changes in poison concentration. Roots proved to be the most sensitive to the effects of poisons, and their length and weight indicators most clearly reflect the nature and degree of the influence of poisons on plant growth.
The specific influence of physiologically active substances of humus nature specifically on the root system is also known. Therefore, experiments were set up to fulfill the task set above, i.e., determining the ID50 and the influence of physiologically active humus substances on this indicator. As an example, we present the results of an experiment with granosan on a test culture—cucumbers.
The influence of various concentrations of granosan on the growth of the root system of cucumber seedlings and the significance of the subsequent transplantation of plants onto sodium humate is illustrated in Table 1 and Figure 1. They show that the action of the poison on the growth of the root system is primarily related to its concentration, namely: when soaking seeds in a granosan solution at a concentration of 2·10-9 — 2·10-8%, not only is inhibition of root growth not observed, but even some stimulation is visible.
A granosan concentration of 2·10-7 — 2·10-8% essentially had no effect on root growth, and only starting from a concentration of 2·10-6% does a tendency towards inhibition of root system growth begin to appear, which intensifies with a further increase in concentration. Inhibition of the root system by approximately 50%, i.e., ID50, corresponds to a granosan concentration somewhere close to 2·10-4%. A poison concentration of 4·10-3% is essentially almost completely lethal.
Table 1. Effect of poison and potassium humate on cucumber root length
| Granosan concentration in % when soaking seeds | Growth medium | Root length, mm (M±m) | % increase vs. control (water — medium w/o humate) | % increase vs. control (poison — medium w/o humate) |
|---|---|---|---|---|
| Control without granosan | Without humate | 85.4 ± 7.0 | 100.0 | 100.0 |
| With K humate 0.005% | 135.8 ± 4.6 | 158.9 | 158.9 | |
| 2 × 10-9 | Without humate | 101.6 ± 5.7 | 118.9 | 100.0 |
| With K humate 0.005% | 116.9 ± 9.4 | 136.8 | 115.0 | |
| 2 × 10-8 | Without humate | 87.1 ± 7.4 | 101.9 | 100.0 |
| With K humate 0.005% | 123.7 ± 5.3 | 144.7 | 141.9 | |
| 2 × 10-7 | Without humate | 80.8 ± 9.3 | 94.6 | 100.0 |
| With K humate 0.005% | 106.9 ± 9.9 | 125.1 | 132.3 | |
| 2 × 10-6 | Without humate | 75.5 ± 5.1 | 88.4 | 100.0 |
| With K humate 0.005% | 111.3 ± 7.1 | 130.3 | 147.4 | |
| 2 × 10-5 | Without humate | 66.6 ± 7.6 | 78.0 | 100.0 |
| With K humate 0.005% | 103.1 ± 9.1 | 120.6 | 154.7 | |
| 2 × 10-4 | Without humate | 47.8 ± 3.5 | 55.9 | 100.0 |
| With K humate 0.005% | 76.8 ± 6.5 | 89.9 | 160.7 | |
| 2 × 10-3 | Without humate | 27.3 ± 1.7 | 32.0 | 100.0 |
| With K humate 0.005% | 48.7 ± 2.0 | 57.0 | 324.2 | |
| 4 × 10-3 | Without humate | 2.9 ± 0.2 | 3.4 | 100.0 |
| With K humate 0.005% | 20.5 ± 1.5 | 24.0 | 696.6 |
Fig. 1. Length of cucumber roots depending on granosan concentration in % relative to control without poison:1 — medium without humate; 2 — medium with humate.
Physiologically active humates, as follows from the same table, shift the ID50 of granosan to a concentration of 2·10-3%. Thus, it is clearly seen that physiologically active humates increase plant resistance to the inhibitory effect of poisons. It should be noted that humates, both on their own and against the background of granosan (but up to certain limits of its concentration), have a stimulating effect on plants.
Table 2 illustrates the generalizing characteristic of granosan action depending on concentration.
Table 2. Effect of potassium humate on the nature of the action of various granosan concentrations on cucumber root length
| Characteristic of poison action | Granosan concentration, % | |
|---|---|---|
| Without humate | With potassium humate 0.005% | |
| Stimulating | 2 × 10-9 | 2 × 10-9 — 2 × 10-8 |
| Neutral | 2 × 10-8 | 2 × 10-5 — 2 × 10-4 |
| Inhibiting | 2 × 10-5 — 2 × 10-4 | 2 × 10-4 — 2 × 10-3 |
| Lethal (LD84) | 4 × 10-3 | > 4 × 10-3 |
Influence of physiologically active humus substances on relieving the inhibitory effect of various insectofungicides at ID50
In order to answer the posed question, it was necessary to clarify, firstly, whether physiologically active humates relieve toxicosis in plants caused by soaking seeds in solutions of various classification groups of agricultural poisons; secondly, to establish how various agricultural plants are inhibited by different insectofungicides and to what extent the detoxification effect is manifested using potassium humate depending on the characteristics of the plants.
The first question was resolved by setting up short-term experiments with various plants according to the methodology described above. The results of this experiment (Tables 3—7) show that azurin and granosan possessed an inhibitory effect. The damaging effect of phthalan was less noticeable. The action of sulfur occupied a middle ground. As for the action of humate, it was most noticeable against the background of those poisons which exerted the greatest damaging effect.
The question of the specificity of damage by different poisons in connection with the species characteristics of plants, as well as their reaction to physiologically active substances, can be fully clarified only in the complete ontogenesis of plants.
Table 3. Influence of physiologically active humate on relieving the damaging effect of Phthalan 0.5% on seeds of agricultural plants
| Crop | Experiment Scheme | Root length, mm | Height of above-ground mass, mm | |||
|---|---|---|---|---|---|---|
| Seeds soaked in | Transplanted to | M±m | % to control | M±m | % to control | |
| Cucumbers | Water | Without humate | 106.0 ± 3.4 | 100.0 | 46.3 ± 1.2 | 100.0 |
| With K humate 0.005% | 117.4 ± 5.6 | 110.8 | 59.2 ± 1.7 | 127.7 | ||
| Phthalan solution | Without humate | 92.8 ± 4.6 | 87.5 | 36.8 ± 1.9 | 79.5 | |
| With K humate 0.005% | 104.6 ± 3.6 | 98.7 | 54.9 ± 1.6 | 118.5 | ||
| Radish | Water | Without humate | 54.9 ± 3.8 | 100.0 | 47.4 ± 2.1 | 100.0 |
| With K humate 0.005% | 101.8 ± 6.4 | 185.9 | 62.9 ± 1.9 | 132.7 | ||
| Phthalan solution | Without humate | 30.7 ± 2.6 | 56.0 | 34.3 ± 1.6 | 72.4 | |
| With K humate 0.005% | 79.3 ± 5.5 | 144.5 | 60.4 ± 3.1 | 127.3 | ||
| Tomatoes | Water | Without humate | 82.8 ± 3.1 | 100.0 | 22.0 ± 1.1 | 100.0 |
| With K humate 0.005% | 138.5 ± 3.8 | 138.6 | 29.9 ± 0.8 | 135.5 | ||
| Phthalan solution | Without humate | 71.8 ± 3.2 | 86.6 | 15.1 ± 0.7 | 68.6 | |
| With K humate 0.005% | 93.4 ± 2.7 | 93.4 | 24.5 ± 0.9 | 111.9 | ||
Table 4. Influence of physiologically active humate on relieving the damaging effect of Thiophos 0.01% on seeds of agricultural crops
| Crop | Experiment Scheme | Root length, mm | Height of above-ground mass, mm | |||
|---|---|---|---|---|---|---|
| Seeds soaked in | Transplanted to | M±m | % to control | M±m | % to control | |
| Sugar beet | Water | Without humate | 54.9 ± 3.3 | 100.0 | 27.1 ± 0.9 | 100.0 |
| With K humate 0.005% | 70.5 ± 4.4 | 128.5 | 36.3 ± 1.4 | 133.8 | ||
| Thiophos solution | Without humate | 33.4 ± 4.2 | 60.6 | 25.3 ± 1.1 | 93.3 | |
| With K humate 0.005% | 65.7 ± 5.7 | 119.8 | 30.0 ± 1.2 | 110.8 | ||
| Tomatoes | Water | Without humate | 80.7 ± 3.3 | 100.0 | 23.1 ± 1.9 | 100.0 |
| With K humate 0.005% | 110.5 ± 3.4 | 142.7 | 29.2 ± 1.2 | 126.2 | ||
| Thiophos solution | Without humate | 56.3 ± 5.3 | 69.8 | 19.1 ± 0.6 | 82.7 | |
| With K humate 0.005% | 109.2 ± 3.3 | 75.9 | 27.3 ± 1.5 | 118.1 | ||
| Cucumbers | Water | Without humate | 80.3 ± 1.7 | 100.0 | 35.9 ± 1.2 | 100.0 |
| With K humate 0.005% | 102.5 ± 7.5 | 127.6 | 61.3 ± 3.1 | 170.5 | ||
| Thiophos solution | Without humate | 56.0 ± 4.2 | 69.7 | 37.0 ± 1.1 | 102.9 | |
| With K humate 0.005% | 61.0 ± 4.3 | 75.9 | 55.0 ± 1.7 | 153.1 | ||
| Sunflower | Water | Without humate | 99.7 ± 5.3 | 100.0 | 21.0 ± 0.5 | 100.0 |
| With K humate 0.005% | 133.0 ± 3.5 | 133.6 | 24.4 ± 0.7 | 116.3 | ||
| Thiophos solution | Without humate | 76.4 ± 5.5 | 76.7 | 26.5 ± 1.3 | 126.4 | |
| With K humate 0.005% | 103.9 ± 9.1 | 104.2 | 35.5 ± 1.5 | 169.5 | ||
Table 5. Influence of physiologically active humate on relieving the damaging effect of Azurin 1% on seeds of agricultural crops
| Crop | Soaking of seeds | Transplant variant | Root length (mm, M±m) | % to control (roots) | Height of above-ground mass (mm, M±m) | % to control (mass) |
|---|---|---|---|---|---|---|
| Sugar beet | Water | Without humate | 54.8 ± 3.3 | 100.0 | 27.1 ± 1.0 | 100.0 |
| With K humate 0.005% | 70.5 ± 4.4 | 128.5 | 36.3 ± 1.4 | 133.8 | ||
| Azurin solution | Without humate | 2.3 ± 0.8 | 4.2 | 17.8 ± 0.8 | 65.8 | |
| With K humate 0.005% | 24.3 ± 2.6 | 44.3 | 24.3 ± 1.0 | 89.5 | ||
| Tomatoes | Water | Without humate | 82.8 ± 3.1 | 100.0 | 22.0 ± 1.1 | 100.0 |
| With K humate 0.005% | 114.8 ± 3.8 | 138.6 | 29.9 ± 0.8 | 135.5 | ||
| Azurin solution | Without humate | — | — | — | — | |
| With K humate 0.005% | 52.7 ± 1.8 | 63.6 | 24.4 ± 0.5 | 110.7 | ||
| Cucumbers | Water | Without humate | 80.3 ± 1.7 | 100.0 | 35.9 ± 1.2 | 100.0 |
| With K humate 0.005% | 102.5 ± 7.5 | 127.6 | 61.3 ± 3.1 | 170.5 | ||
| Azurin solution | Without humate | — | — | 7.3 ± 0.9 | 20.4 | |
| With K humate 0.005% | 51.1 ± 3.7 | 63.7 | 26.3 ± 1.3 | 73.1 | ||
| Sunflower | Water | Without humate | 62.9 ± 7.5 | 100.0 | 45.2 ± 2.9 | 100.0 |
| With K humate 0.005% | 74.0 ± 2.0 | 117.7 | 52.1 ± 3.2 | 115.2 | ||
| Azurin solution | Without humate | 5.0 ± 2.0 | 7.9 | 14.6 ± 1.0 | 32.4 | |
| With K humate 0.005% | 5.0 ± 2.6 | 26.1 | 30.5 ± 2.5 | 67.5 |
Table 6. Influence of physiologically active humate on relieving the damaging effect of Granosan 0.02% on seeds of agricultural crops
| Crop | Soaking of seeds | Transplant variant | Root length (mm, M±m) | % to control (roots) | Height of above-ground mass (mm, M±m) | % to control (mass) |
|---|---|---|---|---|---|---|
| Cucumbers | Water | Without humate | 39.0 ± 1.6 | 100.0 | 19.7 ± 0.2 | 100.0 |
| With K humate 0.005% | 81.5 ± 6.8 | 208.9 | 19.6 ± 0.3 | 99.5 | ||
| Granosan solution | Without humate | 2.6 ± 0.7 | 6.2 | 15.2 ± 0.7 | 76.8 | |
| With K humate 0.005% | 77.1 ± 3.0 | 199.8 | 16.1 ± 1.2 | 81.5 | ||
| Radish | Water | Without humate | 54.9 ± 3.8 | 100.0 | 47.4 ± 2.1 | 100.0 |
| With K humate 0.005% | 101.8 ± 6.4 | 185.4 | 62.9 ± 1.9 | 132.7 | ||
| Granosan solution | Without humate | 48.9 ± 6.6 | 89.1 | 26.3 ± 2.4 | 55.4 | |
| With K humate 0.005% | 60.7 ± 6.0 | 110.6 | 48.1 ± 2.9 | 101.4 | ||
| Tomatoes | Water | Without humate | 82.8 ± 3.1 | 100.0 | 22.0 ± 1.1 | 100.0 |
| With K humate 0.005% | 114.8 ± 3.6 | 138.6 | 29.9 ± 0.8 | 135.6 | ||
| Granosan solution | Without humate | 25.6 ± 0.9 | 30.8 | 12.9 ± 0.7 | 58.5 | |
| With K humate 0.005% | 57.3 ± 3.1 | 69.1 | 28.8 ± 0.6 | 108.0 |
Table 7. Influence of physiologically active humate on relieving the damaging effect of Sulfur 0.3% on seeds of agricultural crops
| Crop | Experiment Scheme | Root length, mm | Height of above-ground mass, mm | |||
|---|---|---|---|---|---|---|
| Seeds soaked in | Transplanted to | M±m | % to control | M±m | % to control | |
| Cucumbers | Water | Without humate | 106 ± 3.4 | 100.0 | 46.3 ± 1.2 | 100.0 |
| With K humate 0.005% | 117.4 ± 5.6 | 110.8 | 59.2 ± 1.7 | 127.7 | ||
| Sulfur solution | Without humate | 33.3 ± 1.6 | 31.4 | 37.6 ± 1.2 | 81.1 | |
| With K humate 0.005% | 49.9 ± 3.7 | 47.1 | 57.2 ± 2.2 | 123.6 | ||
| Radish | Water | Without humate | 54.9 ± 3.8 | 100.0 | 47.4 ± 2.1 | 100.0 |
| With K humate 0.005% | 101.8 ± 6.4 | 185.4 | 62.9 ± 1.9 | 132.7 | ||
| Sulfur solution | Without humate | 27.2 ± 4.3 | 49.6 | 39.2 ± 1.9 | 82.7 | |
| With K humate 0.005% | 39.9 ± 7.9 | 163.7 | 59.6 ± 2.6 | 125.8 | ||
| Tomatoes | Water | Without humate | 82.8 ± 3.1 | 100.0 | 22.0 ± 1.1 | 100.0 |
| With K humate 0.005% | 114.8 ± 3.6 | 138.6 | 29.9 ± 0.8 | 135.5 | ||
| Sulfur solution | Without humate | 69.1 ± 2.5 | 83.4 | 14.1 ± 0.7 | 64.0 | |
| With K humate 0.005% | 74.0 ± 2.6 | 89.3 | 23.6 ± 0.4 | 107.3 | ||