The purpose of writing on this subject is twofold. First, it aims to draw the attention of the scientific community to the real possibility of stearic acid’s stimulating effects on plants.
Second, the publication of these results should make them available for further evaluation of the potential benefits of using this material in plant growth stimulation.
Stearic acid is one of a group of long-chain fatty acids found in plant and animal cells. It is very widespread in nature, the most common being incorporated into triglycerides.
It is a solid, white amorphous powder. Other physical properties include molecular weight 248.47; density 0.747 g/ml; melting point 393 degrees Celsius, solubility 0.034 g. At 100 ml. Of water.
It is known to have surfactant properties and is only slightly soluble in polar and non-polar solvents. Because of its surfactant properties, it has been widely used in the manufacture of soaps and detergents. It is also known to promote the growth of certain soil organisms, such as bacteria.
This report describes the results obtained on five different varieties of vegetable plants and one flowering plant to illustrate the general effects that plant growth stimulation may produce.
It was also observed that other types of affected plants grew faster after treatment with stearic acid.
These affected plants include: Pereskia cactus (“lemon vine”) has been growing very slowly for three months. After treatment, it grew to more than 15 feet in length in five months. A two-year-old Swedish ivy plant has twice as many new leaves as the old leaves two months after the start of treatment.
Finally, after six months of treatment, a hibiscus plant cut from another plant grew larger than its untreated parent.
Tomatoes and other vegetables (radish, broccoli, cabbage) and cactus plants have also been observed, stearic acid alone can stimulate their growth rate, so it is claimed to be a universal plant stimulant.
Test results for beans, pumpkin, carrots, red beets, corn, and marigold are reported here. Only use stearic acid powder to treat plants. The control plants were untreated. No additional watering is used in the outdoor garden. Only normal rainfall reaches the plants.
The method used is to put about 2 grams of stearic acid powder under the soil, close to the plant, and when the plant is two to three weeks old, it has grown true leaves. This has been found to be a necessary procedure because when the seeds are planted in soil that has been treated with stearic acid, a decrease in the number of germinated seeds is observed.
In another experiment, when pea seeds were placed in water containing some stearic acid, the seeds swelled and ruptured within three or four days; forming a white gel-like substance. Then, treatment of seeds with stearic acid seems to have an adverse effect on the germination rate of the seeds.
The observed reduction in the amount of germination, coupled with the significant slowdown of most treated seedlings, confirms the necessity of adding stearic acid after the plants have grown beyond the seedling stage in order to get the most benefit from this method treatment.
Summary of results
Compared with untreated plants, the yield of legumes treated with stearic acid is almost twice the number and weight of pods per plant. Fifteen control and treated plants were tested. For the control plants, the average number of pods/plants was 14, while for the treated plants, the average number of pods was 25.
For carrots, the average root weight increased by 30%; this was the lowest yield increase obtained in this test. Twenty plants were tested, including control plants and treated plants. The average weight of the control was 31 grams, and for the treated plants, the average weight obtained was 40 grams.
Compared with the control, the red beet weight of the treated plants increased by 60%. Eleven control plants and eleven treated plants were tested. The average weight of the control plants was 168 grams, while the average weight of the treated plants was 385 grams.
Compared to the control, the treated pumpkin plants were stimulated to produce twice as large fruits. Twelve plants were tested, including control plants and treated plants. The average weight of the control plants was 1.5 pounds, while the fruit weight of the treatment plants was 3.0 pounds.
Compared with the control plants, the treated marigold plants were twice as large and had twice the number of flowers. The average height of the twelve controls was 6 inches. The height of the treated plants is 12 inches.
The control plants had an average of 10 flowers, while the treated plants had an average of 20 flowers.
Compared to the control, corn gave very different results, with the average weight per ear produced by the treated plants even lower. Since each plant only gets 2 or 3 ears, the largest ear in each plant is weighed. Twelve plants were measured. The average ear weight of the control plants was 162 grams, while the average ear weight of the treated plants was 144 grams. The conclusion is that no effect of stearic acid on corn was observed.
As mentioned earlier, subsequent tests confirmed that the most suitable application time is about one week after germination; for legumes that have passed the seedling stage.
During other tests, it was found that if excessive stearic acid (radish, red beet, and cabbage) was used, the growth of some of the same plant varieties that were stimulated would be inhibited. This effect occurs when an excessive amount of powdered material is placed in the soil surrounding potted plants in a greenhouse.
Therefore, it is not recommended to use this treatment method for indoor plants or other potted plants. In this case, watering with a saturated stearic acid solution may be more beneficial.
Similarly, it is speculated that this material may accumulate in outdoor areas used for cash crops after many years of use, resulting in poor seed germination and loss of plant vitality. Therefore, evaluating spraying procedures during the growing season may produce better results; thus requiring less material and less expense.
Since chemical fertilizers or fertile soil may form metal salts of this compound, this procedure is also recommended. This situation may interfere with the expected beneficial effects of free stearic acid.
Proposed mechanism of stearic acid’s effect on plants
Since plants only absorb the amount of stearic acid dissolved in water, the amount used by plants must be very small. The solubility of stearic acid in water (0.034 g/100 ml of water) shows that only a small amount can be provided to plants to exert a stimulating effect.
This suggests that this material may be a plant hormone. Since hormones are known to stimulate enzymes, it is necessary to determine which enzyme systems may be affected.
In this report, plants that are stimulated (such as beans, red beets) are called C-3 plants; and corn that is not stimulated in these tests is called C-4 plants. Then, the mechanism of stearic acid may lie in its effect on one of the different metabolic pathways that distinguish these two plants.
C-3 type plants are plants that operate through the Calvin cycle of photosynthetic reaction, and C-4 type plants are plants that have different intermediates in the photosynthetic reaction cycle. C-3 plants use 3-phosphoglyceric acid as a carbon dioxide fixation product.
C-4 plants use malic acid, aspartic acid and oxaloacetic acid as carbon dioxide fixation products. The two systems also use different enzymes to produce these acids.
The stimulation mechanism of stearic acid in the enzymatic system is thought to be in the Calvin cycle of photosynthesis reaction. Specifically, it is the rate-limiting step of carbon dioxide fixation, in which ribulose 1, 5 diphosphate is converted to 3 phosphoglycerate; the reaction catalyzed by reibulose 3, 5 diphosphate carboxylase is considered to be the affected system.
A further consideration might be to try to determine why there is so much of this enzyme (40% of dry weight) in leaf tissue. Generally, enzymes are only present in small amounts, and their activity is limited by the amount of substrate available.
The amount of substrate carbon dioxide appears to be the main limiting factor for the activity of this enzyme. This may indicate the existence of a large number of enzymes-to ensure that all available carbon dioxide is easily used by plants. Another possibility is that early in the evolutionary history of plants, there may be a completely different atmosphere, which is rich in carbon dioxide, and plants rich in enzymes are more likely to use carbon dioxide.
Therefore, it seems that in order to more effectively increase the growth rate of plants, the use of carbon dioxide and stearic acid together will be a more favorable treatment method. Of course, enclosed areas of the greenhouse may be required to retain the excess carbon dioxide released into the atmosphere.
A summary of the significant effects of stearic acid on plants shows that it stimulates C-3 type plants; it is more effective at concentrations lower than saturated aqueous solutions, and can even inhibit plant growth when a large excess of acid is used.
Except for the experimental results recorded here, all other observations were made by visually comparing the sizes of the treated plants and the controls.
It is therefore proposed that the observed stimulating effect of stearic acid is due to its hormone-like effect on plants.
Many variables obtained in the environment may affect the results of any test program.
However, the author still claims to obtain the observed results and is sufficient to verify the stimulating effect of stearic acid on plants proposed here.