PHYTOCIDAL PLANTS
Phytocidal plants are those that release special substances that are harmful to various bacteria, rust and mold fungi, and protozoa. Some phytocides can kill horseflies, flies, ticks, and other insects. A number of phytocides destroy the pathogens of dysentery, typhoid fever, paratyphoid, and others.
As is known, the founder and creator of the doctrine of phytocides is the great Russian scientist, Doctor of Biological Sciences, Professor Boris Petrovich Tokin. In his remarkable works, he developed the doctrine of phytocides and demonstrated their significant importance in nature and human life.
The destructive action of phytocides has not yet been fully studied. However, what is already known to science indicates that phytocides are very peculiar substances, both volatile and non-volatile, harmful not only to bacteria, fungi, and insects but even to mammals. For instance, there are facts that phytocides from cherry laurel caused the death of rats.
Phytocides from marsh tea intoxicated animals and humans, while phytocides from ash trees caused burns on human skin.
The tropical tree — Marcinnella, growing on the Antilles, releases volatile substances that cause severe poisoning in humans when inhaled.
With phytocides, the plant seems to protect itself and, in a way, disinfects its environment.
However, the mystery of phytocides is still not fully revealed. B. P. Tokin notes on this matter: “... Phytocides are only a small part of some complex processes, a small page in the thick book of nature, a small stroke in the complex relationships between plants, animals, and microbes.”
Furthermore: “... Phytocides of plants, regardless of their chemical composition, do not necessarily play the role of protective substances only. They perform this role only when the plant is injured, under the influence of harmful substances released by bacteria, when affected by insects, etc. But they can also play some other, even diverse role in a normal, healthy plant organism, forming part of the protoplasm of cells or intercellular substances. For example, they may participate in metabolism; the release of large amounts of volatile organic substances may play a role in reducing or enhancing heat dissipation, in the influx of oxygen, etc.”
Thus, the role of phytocides is multifaceted. It should be noted that the insecticidal properties of phytocides change significantly even in the same plant, depending on the phases and stages of development, the time of year, and other factors.
It has been observed that in buds and just blossomed flowers, there are more phytocides, while towards the end of flowering, their quantity decreases.
In fruits at an early stage of development, there are more phytocides than in ripe fruits.
B. P. Tokin points out that “... some phytocides can suppress respiration, others can dissolve the surface layers of protoplasm, and others can change some important components of protoplasm essential for life — enzymes, etc.”
Phytocides are released not only by higher plants but also by lower plants: blue-green algae and some fungi. This phenomenon is characteristic of the entire plant world.
B. P. Tokin presents an interesting fact.
“In South Africa, in 1927 and subsequent years, many thousands of heads of cattle died from poisoning by phytocides released by the rapidly proliferating blue-green algae in water bodies. If an animal eats a lot of these algae, it dies in severe agony, as if it had been given a terrible poison — strychnine. Death in sheep can occur within 6–8 hours, in horses — within 8–24 hours, and in pigs — within 3–4 hours.”
F. Vent believes that “... Millions of tons of volatile organic substances from plants, oxidizing and decomposing under the influence of light, release an enormous amount of energy, which is expressed in thermal form in a truly gigantic figure: more than 1,000,000,000,000,000,000 calories.”
Phytocides of plants contribute to the ionization of atmospheric air.
Thus, phytocides not only protect plants from bacteria, fungi, and insects but also play a significant role in purifying the atmosphere from microorganisms, influencing its thermal regime and ionization.
B. P. Tokin asserts that thuja reduces the number of microbes in the atmosphere by 67%, small-flowered chrysanthemum — by 66%, cyperus — by 59%, pasture ryegrass — by 58%, and large-flowered chrysanthemum — by 55%. Indoor plants — geranium and begonia — by 43%, and asparagus — by 38%.
Thus, ornamental plants not only have aesthetic value but also purify the air from bacteria.
Special studies have established that a single specimen of tree-like juniper can release 30 grams of volatile substances in one day, while one hectare of juniper forest can release 30 kg of such substances.
Currently, phytocides are widely used in agriculture, veterinary medicine, medicine, food industry, and biology — mainly to clarify the interactions between plants and for other purposes.
Phytocides are especially widely used in agriculture. Phytocides from sand immortelle — arenarin are used for treating tomato and cabbage seeds. Arenarin positively affects seed germination, accelerates their growth and development, increases yield, and most importantly, reduces the susceptibility of tomatoes to bacterial cancer, black bacterial spotting, apical and other rots, as well as viral diseases — mosaic, stolbur, and bronzing of tomatoes.
The use of arenarin in Ukraine resulted in an increase in yield worth 11 million rubles over the year.
Pre-sowing treatment of seeds of agricultural plants such as sugar beet, corn, wheat, rye, alfalfa, and clover with phytocides effectively helps in the fight against smut and rust. The same phytocides from onion are a good means in the fight against smut and rust developing on rose hips.
Phytocides are widely used in medicine. For instance, penicillin is used to treat various diseases — sepsis, gonorrhea, syphilis, relapsing fever, and others.
Streptomycin, obtained from lower plants, is widely used to treat tuberculosis and tularemia.
The volatile phytocides of lemons and oranges kill pathogenic bacteria; they are used for sore throat and other diseases. Phytocides from garlic kill the pathogens of typhoid fever, paratyphoid, dysentery, and cholera.
The preparation “Sativin,” created by Professor T. D. Yanovich from garlic juice, is successfully used for the treatment of diphtheria and tuberculosis.
Phytocides from fir bark kill the diphtheria bacillus. Phytocides from horseradish, garlic, onion, radish, and bloodroot promote the release of important substances for digestion in the stomach and intestines.
Currently, a device has been invented that allows phytocides to be introduced into the gastrointestinal tract for the treatment of many gastrointestinal diseases.
During the war, garlic phytocides were successfully used to treat long-healing purulent wounds.
A preparation “Imanin” obtained from St. John's wort phytocides is widely used for the treatment of runny nose, tuberculosis, whooping cough, burns, and other diseases.
Phytocides from common onion, horseradish, common juniper, and pine are used to treat trichomonas colpitis.
A preparation made from fir phytocides is used to purify the air in children's nurseries from bacteria. The preparation in the form of aerosols is sprayed into the air. With this method of treatment in premises, diphtheria bacilli died by 80% and golden staphylococci by 64%.
Scientists in Kazakhstan have established that the phytocides of indoor plants amaryllis, agapanthus, zephyranthes, and hippeastrum are more potent than garlic phytocides.
For nervous people, geranium phytocides improve sleep. For this, a person suffering from insomnia inhales the air from a geranium bush placed approximately 60 cm away for 10 minutes. After 10 days of such treatment, sleep normalizes.
We have provided only a few examples of the use of phytocides by doctors for the treatment of various diseases. In reality, phytocides are used much more widely in medicine.
Phytocides from plants are also used in veterinary medicine.
Feeding bees onion extract increases their lifespan by 40%.
Phytocides suppress the activity of viruses. Under the influence of phytocides from tobacco seeds, “dissolution” of viral particles was observed.
Scientists have used phytocides from fragrant poplar in the fight against animal foot-and-mouth disease.
It has been established that phytocides from forage grasses affect not only the digestion of animals and the microflora of the gastrointestinal tract but also livestock products — for example, milk.
For instance, cattle that consumed silage from Sosnowski's hogweed produced milk that soured 8–10 hours later than usual. Rabbits that breathed garlic phytocides retained the garlic smell for a long time after slaughter.
Phytocides find wide application in the food and flavoring industry. Since ancient times, people have used bay leaves, currant leaves, and other spices when salting vegetables, which not only served as flavoring substances but also acted as antiseptics.
Under the influence of phytocides from mustard, onion, and garlic, food products are preserved longer.
B. P. Tokin asserts that under the influence of phytocides from cherry laurel leaves and mustard vapors, meat in a closed vessel does not spoil for a year.
Potatoes and onions are well preserved for a long time when sprinkled with powder from dried and crushed leaves of lemon balm.
In some plants (dill, eggplant, etc.), phytocides manifest their action when heated, which is especially important for canning.
B. P. Tokin managed to preserve Antonovka apples for 15 years using phytocides, and cleaned chicken eggs for 25 years.
However, phytocides do not always have a destructive effect on bacteria. Academician N. G. Kholodny (Ukraine) established that in some cases, phytocides, on the contrary, favor the reproduction and life of bacteria.
That is why more attention should be paid to the study of phytocidal plants.
In Kyrgyzstan, among numerous species of useful plants, there are also those that release phytocides.
However, systematic studies of phytocidal plants in Kyrgyzstan have not actually been conducted. Only in recent years, Professor V. I. Tkachenko (Academy of Sciences of the Kyrgyz SSR) and the Department of Botany of the Kyrgyz State University named after the 50th anniversary of the USSR, led by the author of this work, have organized experiments to study phytocidal plants of Kyrgyzstan. The research focused on the decorative flora and the flora of meadow plants. The studies showed that more than 100 phytocidal plants are found in the territory of Kyrgyzstan.
The most valuable among them are various species of juniper, walnut, bird cherry, Semenov fir, Schrenk spruce, oleaster, biota, jujube, sweet clover, wormwood from the seriphidium section, onion, carrot, tomato, pepper, yarrow, quince, tamarisk, and many others.
Let’s briefly consider the characteristics of the main phytocidal plants of Kyrgyzstan.
Half-spherical Juniper. A low evergreen tree with scale-like leaves. It grows in a variety of conditions. It is found in steppes and meadow-steppes, in meadows. It forms forests and sparse forests, sometimes occurring as solitary specimens among steppes, meadows, forests, and on rocks.
The area of juniper forests in Kyrgyzstan is 316.6 thousand hectares. These are the largest juniper forests in the USSR. Juniper releases phytocides not only in its living state in nature; a broken branch of juniper continues to release phytocides for 2–3 weeks.
Juniper should be used more widely for landscaping settlements not only for decorative purposes but also for improving the atmosphere.
Of all juniper species, the half-spherical juniper adapts most successfully. It should be used in green construction.
Juniper releases phytocides in winter and summer. In summer, phytocides are more lethal — under their influence, the death of protozoa was observed after 10 minutes, while in winter — after 1.5 hours.
Oleaster. Oleaster grows as a small tree up to 7 m high or as a shrub. The bark is reddish-brown, young branches are silvery with thorns. The leaves are elongated-lanceolate and silvery.
The flowers are bell-shaped and yellowish. It blooms in May and bears fruit in August.
It grows along riverbanks up to 2800 m above sea level in all regions of Kyrgyzstan. During flowering, it emits a pleasant aroma.
Oleaster is a valuable species. Its bark and leaves contain tannins, and the fruits are edible.
It is an excellent honey plant. Due to the presence of thorns, it is used as a living fence. It effectively stabilizes sands and is used for phytomelioration purposes. The wood has valuable qualities and is used for small crafts.
In gardens and street plantings, eastern oleaster is cultivated. It, like narrow-leaved oleaster, also releases phytocides.
Various species of oleaster should be used more widely for green construction.
Tamarisk. Several species of tamarisk grow in Kyrgyzstan — elongated, loose, multi-branched, juniper, Hohenacker, and thin-spiked. These are shrubs or small trees with scale-like leaves and beautiful clusters of small pink, whitish, or purple flowers.
Tamarisks grow in river valleys on saline soils (in solonchaks, solonetzes), on clayey, gravelly, and saline sites. They do not form large thickets. However, they can be found in small groups or as solitary clumps in the Fergana, Alai, Talas, Chui, and Naryn valleys. They are phytocidal.
Tamarisk grows well and develops in cultivation. Therefore, it should be used more widely for landscaping settlements.
Walnut. It is a valuable phytocidal plant. Recently, it has been used in street plantings.
The pulp from walnut leaves kills protozoa (simple organisms) within 18–20 minutes. Even undamaged walnut leaves release phytocides.
Under the canopy of a walnut tree, there is usually very little grass. Apparently, walnut phytocides prevent the development of other plant species.
Researchers of walnut forests have noticed that prolonged stay under the canopies of walnut trees causes headaches, weakness, and malaise in many people. It is possible that this is influenced by walnut phytocides. However, this phenomenon should be studied carefully.
Crimean Pine. This tree is widely used in street plantings, in squares and parks of settlements in Kyrgyzstan.
The pulp of the pine leaf kills protozoa within 20 minutes, rupturing the outer shell of the protozoa and releasing all contents, as if from a burst bag.
Common Oak. It is widely used for landscaping cities and towns in Kyrgyzstan. This beautiful tree with pinnate-lobed leaves can be seen in groves, parks, and alleys.
In our experiments, oak phytocides killed protozoa within 6–7 minutes.
White Mulberry. Mulberry is used in Kyrgyzstan not only for landscaping settlements but is also cultivated in fields, especially in the south of Kyrgyzstan. Mulberry is an excellent phytocidal plant. The pulp made from its leaves kills microorganisms within 20 minutes.
Black Currant. Grown for its berries, which are rich in vitamins and medicinal properties. The leaves of black currant release phytocides. The phytocides from the pulp of black currant leaves kill protozoa within 12–15 minutes.
Common Viburnum. Besides its decorative qualities, it is also phytocidal. The phytocides from the pulp of viburnum leaves kill microorganisms within 15–18 minutes.
Jasmine. This is a decorative shrub with delicate white flowers. It is a phytocidal plant. Its phytocides kill protozoa within 10–12 minutes.
Common Bird Cherry. It is known that bird cherry is an excellent plant not only for decoration but also for phytocides. Its phytocides kill not only microorganisms but also insects. Therefore, it is necessary to use it more widely in the greening of cities and towns.
Experiments have shown that phytocides are also released by smooth elm, horse chestnut, white poplar, balsam poplar, and many other plants.
Among herbaceous decorative plants, amaryllis is highly phytocidal.
Its phytocides kill protozoa within one minute.
Among other indoor decorative plants with phytocides, we can mention begonia; the phytocides from its leaves kill microorganisms within 35 minutes.
Experiments have shown that among herbaceous plants grown in flowerbeds and gardens, the following species have phytocidal properties.
Hybrid Petunia. The phytocides from petunia leaves kill microorganisms within 1 hour. Flowers and stems contain 3–4 times less phytocides.
Two-colored Rudbeckia. The phytocides from rudbeckia leaves kill microorganisms within 15–20 minutes.
Bloody Red Sage. It is widely used for creating flowerbeds and gardens. It blooms for a long time, almost until the first autumn frosts, and beautifully decorates cities and towns with its bloody red flowers.
Its phytocides kill microorganisms within an hour.
Elegant Zinnia. This plant is often found in flowerbeds and gardens. Its phytocides kill microorganisms within 20–30 minutes.
Chinese Aster. The phytocides from its leaves kill microorganisms within 50–60 minutes.
Pleasant Alternanthera. Grown in flowerbeds. The phytocides of this decorative plant kill microorganisms within 20–25 minutes.
Pansies. Their phytocides kill microorganisms within 50–60 minutes.
Drummond Phlox. The phytocides from its leaves kill microorganisms within 1 hour and 20 minutes.
It should be noted that a number of ornamental plants contribute to the favorable development of microorganisms. These include: marigolds or calendula, primrose, tagetes, and others.
Therefore, when selecting ornamental plants, their phytocidal properties should be taken into account.
Let’s consider the phytocidal properties of meadow plants.
Experiments have shown that many meadow plants are phytocidal. These include: Dzhungarian aconite, tall aconite, Poltoratsky's larkspur, multi-flowered buttercup, mountain sneezewort, common caraway, blue onion, stinking bellflower, clustered bellflower, common oregano, fragrant jujube, and others.
Dzhungarian Aconite. The highest concentration of phytocides is found in the flower. The phytocides from the flowers kill microorganisms within 27 minutes. The flowers of tall aconite kill microorganisms within 1 hour and 15 minutes.
Poltoratsky's Larkspur. The phytocides from its leaves kill microorganisms within 1 hour and 22 minutes.
Phytocides from the leaves of multi-flowered buttercup led to the death of microorganisms within 2 hours and 19 minutes.
From the Lamiaceae family, the phytocides of common oregano and fragrant jujube were tested.
Oregano phytocides killed microorganisms within 1 hour and 30 minutes, while jujube phytocides killed them within 43 minutes.
Among the Asteraceae family, the variegated buzulnik has phytocidal properties. Its phytocides led to the death of microorganisms within 35 minutes. The phytocides from common yarrow caused the death of microorganisms within 2 hours. Especially strong phytocides are released by Turkestan ash.
The death of microorganisms occurs here within 1–2 minutes.
Above, we have provided only preliminary exploratory results of experiments. Further work on studying the phytocides of plants growing in Kyrgyzstan should continue. However, what is already known about phytocides should be used more widely in agriculture — and for fulfilling the Food Program.
It should be noted that recently, the phytocides of ornamental plants in Frunze have been studied by Professor V. I. Tkachenko of the Botanical Garden of the Academy of Sciences of the Kyrgyz SSR, and employees of the Women's Pedagogical Institute named after V. V. Mayakovsky, I. N. Dzyuban, A. Chimanova. According to their data (1985), the microflora of the air in Frunze is quite numerous. However, under the influence of phytocides from half-spherical juniper, Virginia juniper, walnut, Negundo maple, and Bolle poplar, the number of microorganisms decreases by 4–8 times.
When greening cities and towns, it is essential to apply phytocidal plants primarily, which contribute to improving the atmosphere and ionizing the air.
The most potent phytocidal plants are various species of juniper. A single specimen of tree-like juniper can release up to 30 grams of volatile substances in one day. In the greening of settlements and cities, it is advisable to use half-spherical juniper, Turkestan juniper, and other species more widely.
The natural phytocidal flora should also be considered and used for health-improving activities when organizing recreation homes and resorts.
In addition, it is necessary to expand experiments on studying phytocidal plants of pastures and hayfields, as phytocidal forage plants affect not only animals but also livestock products consumed by humans.
Research should be organized more extensively to determine the effects of natural phytocidal plants on the human body. In particular, this should be taken into account when selecting the assortment of ornamental plants, especially indoor ones, i.e., considering not only their decorative properties but also their phytocidal properties; conducting measures to combat phytocidal plants that harm humans (such as Turkestan ash and others); and removing from the assortment those decorative plants that favor the development of microorganisms (such as canna, marigolds, tagetes, primrose, and others).
The study of the interactions of plants in terms of their phytocidal properties is of great importance in agriculture.
Preliminary studies by several scientists have shown that combined plantings created with consideration of the positive interactions of plants with each other yield better results and higher yields compared to monocultures.