The Influence of Physiologically Active Forms of Humic and Fulvic Acids on the Specific Activity of Meristematic Cells and Corn Growth
Introduction
To understand the nature of the stimulating effect of humic and fulvic acids, it is important to study their influence on various phases of plant growth. Since the key growth process is mitosis, associated with DNA replication, this study aims to identify the correlation between the effect of humate on plant growth and its impact on cell division, the functional state of nuclei, and the amount of DNA in them.
The basis of the work was the hypothesis of L.A. Khristeva, according to which humic and fulvic acids in an ion-dispersed state enhance redox processes, increase the energy potential of the plant, and accelerate ATP synthesis. This, in turn, activates the formation of labile forms of nucleic acids, which affects protein synthesis and the rate of growth processes.
Research Methodology
Experiments were conducted on corn seedlings in triplicate. Seeds were germinated in Petri dishes at a temperature of 23–30°C. After sprouting, they were transplanted onto solutions of the studied substances and inhibitors:
- Stimulants: potassium humate (3.1·10⁻⁵ M), ATP (1.4·10⁻⁵ M).
- Inhibitors:
- RNA synthesis: 8-azaguanine (10⁻³ M), RNA-ase (1 mg/ml).
- DNA synthesis: DNA-ase (1 mg/ml).
- Protein synthesis: chloramphenicol (0.0025%).
- ATP synthesis: 2,4-dinitrophenol (10⁻³ M).
After 36 hours, root length was measured, and cytological studies were conducted:
- Mitotic index was determined (number of mitosis phases per 1000 cells).
- Nuclear volumes of meristematic cells were measured.
- The amount of DNA in nuclei was determined by photometric method.
Research Results
| Variant | Root length (cm) | Mitotic index (‰) | Nuclear volume (conv. units) | DNA per nucleus (conv. units) |
|---|---|---|---|---|
| Water (control) | 5.0 | 45.4 ± 4.9 | 2.88 | 0.310 |
| Potassium humate | 7.8 | 66.6 ± 4.6 | 4.49 | 0.324 |
| ATP | 7.5 | 76.6 ± 6.2 | 5.47 | 0.327 |
| 8-azaguanine | 2.7 | 18.1 ± 0.7 | 1.62 | 0.260 |
| RNA-ase | 2.4 | 9.7 ± 2.9 | 1.88 | 0.300 |
| DNA-ase | 3.7 | 9.0 ± 2.7 | 1.69 | 0.275 |
| Chloramphenicol | 2.6 | 12.5 ± 2.5 | 1.99 | 0.310 |
| 2,4-dinitrophenol | 2.1 | 2.1 ± 0.6 | 0.93 | 0.282 |
Key Observations:
- Stimulants (potassium humate, ATP):
- Increase root length, mitotic activity, and nuclear volume.
- Enhance DNA content in nuclei, confirming their role in activating nucleic acid synthesis.
- Inhibitors:
- 8-azaguanine and RNA-ase suppress growth, reduce mitotic activity, and decrease nuclear volume.
- DNA-ase inhibits DNA synthesis, which affects all studied parameters.
- Chloramphenicol blocks protein synthesis but does not affect DNA content.
- 2,4-dinitrophenol almost completely stops mitosis and sharply reduces DNA levels.
- Reversal of inhibitory effects:
- Transplanting seedlings onto solutions of potassium humate or ATP partially restores growth and mitotic activity.
- The greatest effect was observed for RNA and DNA synthesis inhibitors, weaker for 2,4-dinitrophenol.
Conclusions
- Humic acids and ATP stimulate mitotic activity of meristematic cells, increase nuclear volume and DNA content.
- Inhibitors of RNA, DNA, and protein synthesis suppress cell growth and division. Their effects are partially compensated by physiologically active substances.
- 2,4-dinitrophenol, which disrupts ATP synthesis, has the strongest inhibitory effect, which is weakly reversed by humic acids.
Conclusion
The results confirm the hypothesis about the key role of humic acids and ATP in cellular energy supply and activation of nucleic acid synthesis, which determines their stimulating effect on plant growth.