The Experimental Verification of Promoting Growth by Watering Succulent Plants with Acidic Water
Plant Knowledge Series: Sharing experiences with succulent plants, experimental verification of promoting growth by watering succulent plants with acidic water. Next, the site editor will introduce to netizens.
A year ago, at the urging of several friends, I summarized and wrote an article based on my experience and understanding about the golden section of the pH value for watering Haworthia plants: that is, adjusting the pH of water to 5.0 (anywhere between 4.0-5.5 is fine) with hydrochloric acid, and using this water to water plants or spray can significantly promote plant growth, inhibit the formation of calcium and magnesium crystals and water stains, and help root development and other biological effects.
However, after this acidic water theory was proposed, it was questioned from various aspects. Nevertheless, it is comforting that many friends have achieved very surprising results using the acidic water method.
The acidic water theory is not proposed out of thin air; it has a lot of theoretical background in plant physiology and biochemistry, and is supported by years of practical experience. To help better understand the effects of acidic water, I will introduce my understanding of the mechanism, hoping to get more support. After all, an effective cultivation method can greatly promote the cultivation and breeding of Haworthia in China, and I can do something for the succulent world in my lifetime.
【Mechanism Analysis of Acidic Water Effects】
1. Remove the attachment of calcium and magnesium ions: This has been mentioned extensively in the earliest article on the golden section. It mainly says that although acidic water cannot reduce the hardness of water, it can convert insoluble calcium and magnesium salts into soluble ions, thus helping to remove deposits blocking stomata and root hairs, restoring the plant's respiration and ion exchange ability. Many friends mistakenly understand this point as acidic water being used to remove water alkali or reduce hardness. In fact, acidic water neither reduces hardness nor removes water alkali; it only dissolves water alkali.
2. Proton growth effect and plant expansin: This mechanism was not mentioned in the earliest article because it involves complex knowledge of plant physiology and biochemistry, which is very difficult to understand. However, as the ultimate mechanism of promoting growth with acidic water, it needs to be emphasized here.
Plant growth hormones act on plant cells and, by regulating the proton-ATPase on the cell membrane, affect the distribution of protons (protons = hydrogen ions = acid) inside and outside the cells. Protons inside the cells diffuse to the outside. The protons that diffuse to the outside can exchange with potassium ions, causing potassium ions to enter the cells through other channels (potassium ions are fertilizers). A large number of extracellular protons will promote the further opening of potassium channels, taking in more potassium to balance the cation atmosphere inside and outside the cells. An interesting thing happens: the protons secreted to the outside of the cells will promote the activation of a molecule called "expansin" on the plant cell wall. This molecule can effectively bind to specific areas of the cellulose, the plant cell wall's framework molecule, making this rigid molecule more plastic. Under the internal expansion pressure of the plant cells, the cells rapidly expand. This is the famous cell wall loosening effect, also known as the "acid growth theory."
Hydrogen ions promote expansin, causing the cell wall to relax and the cells to swell, which is exactly the process of the plant growth hormone effect. That is to say, watering with acidic water = stimulating growth hormone.
This cell expansion effect is not only the expansion of plant leaves and stems but also the corresponding extension of root growth, which can be said to be the presentation of the plant's comprehensive growth promotion effect.
3. Promote photosynthesis: An important part of plant photosynthesis is gas exchange, and the stomata on the leaf surface are very important plant organs. Their opening ensures the smooth progress of photosynthesis. Succulent plants belong to the CAM photosynthetic pathway and do not open their stomata during the day. At night, under the combined action of temperature difference, humidity, and other stimulating molecules inside the cells, the stomata open to absorb carbon dioxide for photosynthesis. These stimulating factors are activated through the proton-ATPase in the guard cells of the stomata, just like mentioned above. Protons can promote the swelling of guard cells, increase potassium intake, and then promote the occurrence of polarized contraction in the cells, resulting in the ventilation effect of the stomata.
Therefore, spraying acidic water in the evening can promote the opening of the stomata on the leaf surface and greatly promote the occurrence of the dark reaction of photosynthesis in succulent plants. The dark reaction is the phase of organic matter synthesis, which can provide the plant with more dry matter.
4. Promoting plant growth by inhibiting abscisic acid: Abscisic acid (ABA) is an important inhibitory endogenous hormone in plants, regulating plant dormancy, aging, and growth arrest under adversity. Acidic water can improve potassium intake by increasing proton concentration, promote cell growth, and this process can offset or mask the negative regulatory effect of ABA mediated by calcium ions, thereby removing ABA's inhibition on plants.
【Acid Selection】
The best acidifying substance: hydrochloric acid (hydrochloric acid is currently the most recognized acidifying substance in biochemical and bioactive culture systems, having been used in biology and medicine for hundreds of years. A small amount can significantly change the pH, and although a small amount of chloride ions are mixed in, it does not have a negative effect on succulent plants. In fact, the chlorine content in our tap water has already exceeded this amount of hydrochloric acid. Some friends say that this is a strong acid with strong corrosiveness, but these statements are biased understandings. Only concentrated hydrochloric acid is corrosive. The acidity of the solution after adjusting with hydrochloric acid depends on the pH, not just any hydrochloric acid is a strong acid. Our stomach acid is hydrochloric acid.)
Priority order of acidifying substances:
1. Hydrochloric acid (best)
2. Nitric acid (second best. When the concentration is very low, its oxidizing property can be ignored and has no effect on the plant; it can also supplement nitrogen for the plant, achieving a double benefit; the only drawback is that its oxidizing property may affect some fungicides or other watering components, so it's best not to use it simultaneously with other substances)
3. Acetic acid (uncertain effect. Organic acid, i.e., white vinegar, can adjust acidity, but a lot needs to be added, and it is not as good as hydrochloric acid in adjusting acidity; whether the acetate has an impact on the plant is unclear, so it's best to be cautious or use it intermittently)
4. Citric acid (poorer. Organic acid, weaker in adjusting acidity than acetic acid, and also chelates with trace elements, affecting the plant's absorption of trace elements, occasional use is fine)
Acidifying substances that should not be used:
1. Oxalic acid (the most unsuitable substance. Although oxalic acid can adjust acidity, it forms insoluble calcium oxalate with calcium ions, not only failing to promote growth or dissolve deposits but also causing permanent blockage of stomata and root hairs, which is difficult to rescue in the future)
2. Sulfuric acid (sulfate can form calcium sulfate precipitate with calcium ions, i.e., gypsum; if sulfuric acid is used for adjusting acidity for a long time, the soil in the pot will turn into gypsum... probably can be used to make sculptures)
3. Phosphoric acid (like oxalic acid, phosphoric acid also combines with calcium ions to form insoluble precipitates, contradicting the above theory; although it can also promote growth, it mainly relies on phosphorus supplementation; unless a large amount of phosphoric acid is used, the phosphate can be hydrated to dissolve, but this requires persistent acidity, which is not good for the plant and the rhizosphere environment)
Practices completely unrelated to the acidifying theory:
1. Acidic ion-exchange water (indeed, the ion-exchange resin method is very modern, but the process and the components produced by the exchange require more complex acidifying theory to explain. Whether this method is feasible remains to be seen. At least, no one in biomedicine uses this; they adjust the pH with pure water)
2. Biofermented acidic water (this also has too complex components and is difficult to analyze. It varies from person to person. If you are willing to use it, then use it and see the results)
The above is the detailed content of the experimental verification of promoting growth by watering succulent plants with acidic water, hoping it can be helpful to you!