Prospects for the use of natural terpenoids in agriculture

. As a result of the conducted phytochemical studies of sesquiterpene lactones of some plants of the genus Artemisia, Centaurea, Jurinea, and Handelia of the Asteraceae family and the study of biostimulating, mutagenic, and insecticidal activity of isolated individual lactones and total preparations in rice farming, cotton growing, as well as against termites, the following biologically active environmentally safe natural remedies have been created: an effective stimulant that, when soaking rice seeds, increases the yield 12-14 quintals per hectare as an average, promising mutant lines and two new cotton varieties have been created on the basis of the polar lactone sum (PLS), and anti-termite sesquiterpene lactones have been isolated, which at low concentrations destroy termites by 90-96%.


Introduction
The plant resource of Uzbekistan is very diverse and rich.More than 4,500 species of flowering plants grow on the territory of our republic, and about 3,500 of them are alkaloidbearing, glycoside-containing, coumarin-containing, flavonoid-bearing, and terpenoid.
Modern production in agriculture uses a large list of plant manufacture products against diseases, weeds, insects, and various environmental influences.Many of the products currently used are synthetic, they are quite stable and are not destroyed by the enzymatic systems of plants, accumulate in the harvested crop, and therefore in the body of humans and animals.Currently, to obtain environmentally friendly plant food products, it is necessary to create preparations that meet these requirements.Among the applied methods of plant protection, synthetic agents are widely used [1,2].In recent years, herbal preparations have been of increasing interest, which, according to several indicators, have tangible advantages over synthetic ones.Plant pesticides are slightly toxic, at low concentrations they have various types of biological action and are environmentally harmless to humans and the environment.Although sesquiterpene lactones are relatively unstable compounds, interest in this class is increasing every year, since along with interesting chemical properties and structure, they mainly attract researchers from many countries with a wide range of biological activity.Among them, compounds exhibiting antitumor, anti-inflammatory, analgesic, anti-ulcer, antibacterial, antifungal, antiviral, antiparasitic, and insect repellent activity were identified.Many types of biological activity of these compounds are associated with the presence of an α-methylene-γ-lactone group in their molecule, which reacts through the addition of Michael with free sulfhydryl or amino groups in proteins and alkylates them.
Sesquiterpene lactones, being a large group of secondary metabolites, are widely distributed in flowering plants, and according to the literature data, the structure of more than 5,000 of their representatives with mono-, di-, and tricyclic carbon skeletons has been established to date [3,4].On the territory of our republic, along with wild medicinal plants, pesticide plants are also widespread.Nevertheless, in recent years, due to disorderly plowing, haymaking and grazing, these plants have been severely exterminated and innovative research in this direction is not fully carried out.In this regard, a number of presidential resolutions have been adopted in the republic and to implement them, consistent reforms are being carried out on the protection of medicinal plants and their processing, conditions are being created to increase the export potential of the industry, as well as the integration of science and education.
Mono-and bicyclic sesquiterpene lactones are widely distributed in flowering plants of the Asteraceae family, and they are a valuable, easily accessible source of a variety of medicines and biologically active substances (BAS).
To create and introduce new effective pesticides and medicines into production, it is necessary to expand the phytochemical study on a large scale, as well as the development of optimal methods for the BAS isolation with their further transfer to the study of biological activity.
The majority of sesquiterpene lactones isolated by us mainly from plants of the Asteraceae family and the study of their biological activity showed that they have biostimulating, insecticidal, antifungal, antiparasitic, mutagenic activities and therefore applied scientific research in this direction is very relevant and promising.

Materials and methods
Along with the use of fertilizers, chemical and biological plant protection products, the use of plant growth biostimulators is also one of the important and necessary ways to improve the quality and yield of agricultural crops.To consider the growth-stimulating activity of the terpenoids isolated by us, the following technique was used.
Preparation 1 (Risolid) was used in the form of aqueous solutions with concentrations of 50 g/t of seeds, 75 g/t of seeds, 100 g/t of seeds, 125 g/t of seeds.Rice seeds were soaked in solutions at the above concentrations and in water (control).The treatment exposure is 1 hour.After processing, the seeds were laid out 100 pieces in Petri dishes on filter paper saturated with water.Then the seeds for germination were placed in a thermostat at a temperature of 25 °C.The germination energy and germination of seeds were determined on the 4th and 7th days, respectively, and the repetition of the experiment was carried out four times.
To conduct field tests, the test sample of lactone was dissolved in a minimum amount of alcohol and water was added until a concentration was formed in a ratio of 1:10000.Then the rice seeds were individually immersed in the prepared solution for 24 hours.
When studying the mutagenic effect of the polar sum of Artemisia absinthium (the "PRP" preparation) on cotton, mutant lines were obtained.For field testing, seeds of various cotton varieties were soaked with a preparation in concentration (2,0; 1,5; 1,0; 0,5%) and then they were sown.In concentrations of 2 and 1%, the PRP preparation was also studied as a modifier for relieving depression during irradiation of cotton seeds of the C-6524 variety, and gamma rays of Co 60 were used as mutagenic factors [5,6].
In recent years, Turkestan and the Great Transcaspian termites have been a serious problem in Central Asia, causing enormous damage to historical cultural monuments, buildings, structures, warehouses, and strategic facilities.The results of long-term tests have shown that the chemicals used against termites do not give serious tangible results, and apparently, the main disadvantage of these drugs is their short-term effect.To determine the optimal concentration of antithermitic activity of sesquiterpene lactones, their tests were carried out according to the following method: The weight of each lactone tested (0.5g) was dissolved in a small amount of acetone and the volume was adjusted to 50 ml by adding distilled water.Then 1 ml of the obtained 1.0% solution of the preparation was diluted to 100 ml and a 0.01% solution was obtained, which was then diluted to the required concentrations for testing.

Biostimulating activity
In agriculture in recent years, a variety of plant biostimulators have been used, which increase the yield of agricultural crops than mineral and organic fertilizers.A specific feature of plant growth bioregulators is their ability to influence processes that cannot be regulated by conventional agrotechnical methods of crop cultivation, such as irrigation, the use of fertilizers, etc.The widespread use of plant growth regulators with a versatile spectrum of action also leads to the protection of plants from diseases and pests.This task is also relevant for rice cultivation, since rice is considered one of the main plant foods of the population of Southeast Asia.The most optimal method of using plant growth biostimulators is pre-sowing seed treatment, which increases the energy of seed germination and as a result, fast and friendly shoots appear, the development of the root system and plant biomass increases, and ultimately yields significantly increase.
The growth-regulating activity of a number of sesquiterpenoids was described in [7,8], and it was found that α -santonin (1), zerumbone (2), and C16-guaianolide (3), (Fig. 1) when rice seeds were soaked for 24 hours in solutions of the above compounds at a dilution of 1:10000 increase the yield of rice compared to the control by 14.17% (α-santonin and zerumbone) and 7.5% (C16-guaianolide).Currently, the Edagum SM preparation (produced in Russia) is used in agriculture of Uzbekistan to increase rice yield [9].
The main disadvantage of the biostimulator Edagum SM is the complexity of its application, which consists in repeated processing of rice during the growing season, which is economically unprofitable.In this regard, we have been conducting applied research for a number of years to create a cost-effective, effective stimulator to increase rice yields.
The growth-regulating properties of this sesquiterpenoid, which we have named the preparation "Risolid", allow to effectively increase the yield of rice with a single presowing treatment of rice.Below are the results of biological studies of compound 1.As can be seen from the data in Table 1, this biostimulator has a great influence on the germination of rice seeds.
Table 2 shows the rice yield indicators.Based on the analyses, it can be seen that in the control variant the plant growth was 127 cm, the length of the panicle was 25.3 cm, the weight of the main panicle was 1.8 g, the weight of the side panicle was 0.8 g, and the yield was 55.9 quintals per hectare.In the 2nd variant of the experiment (the Edagum SM preparation), the plant growth was 132 cm, the length of the panicle was 27.8 cm, the weight of the main panicle was 1.8 cm, the weight of the side panicle was 0.9 g, the yield was 65.4 quintals, which was 9.6 quintals higher compared to the control.In 3-4 variants of field experiments (the preparation Risolid 50 and 75 g/t of seeds), the plant growth was 135-136 cm, the length of the panicle was 27.8-27.9cm, the weight of the main panicle was 2.2 cm, the weight of the side panicle was 1.0-1.1 g, the yield was 70.3-70.4quintals, which was 14.4-14.5 quintals higher compared with the control (see Table 2).
The results of the tests show that the proposed preparation Risolid has a high growthregulating activity at low concentrations, which leads to an increase in rice yield, and, thereby, this tool can be used in agriculture to increase rice yield.

Mutagenic activity
To create new varieties, chemical mutagens and ionizing radiation are mainly used in the selection of the starting material in cotton growing.
When studying the mutagenic effect of the polar sum of wormwood (Artemisia absinthium preparation "PRP") on cotton, previously a number of mutant lines was obtained.It was found that at different concentrations, this total preparation has pronounced growth and mutagenic activity.Cotton seeds of varieties C-6524, C-6532, C-9070, etc. were soaked with PRP preparation of various concentrations before sowing (2,0; 1,5; 1,0; 0,5%).The following indicators were analyzed: seed germination, plant survival and the degree of development of traits characterizing productivity.In experimental variants, at concentrations of 1.0 and 0.5%, there is a pronounced stimulation, in particular, in the accumulation of fruit organs on the bush, an increase in the weight of raw cotton per plant, due to an increase in the number and weight of boxes.
This preparation in concentrations of 2 and 1% was used as a modifier to relieve depression during irradiation of seeds.For the study, grade C-6524 was taken, gamma rays Co 60 and the PRP preparation in concentrations of 2 and 1% were used as mutagenic factors.The control variants were non-irradiated seeds simply soaked in water and the second control was simply irradiated seeds.
As a result of experimental studies, promising breeding material was obtained in the form of mutant lines, and two new varieties created passed state tests and surpassed the well-known variety C-6524 in economic and valuable characteristics.From this plant, the structure of a new water-soluble guaiane sesquiterpene lactone with mutagenic activity was isolated and established, which apparently is the active active principle of the PRP preparation [10,11].
Insecticidal activity.Recent studies have shown that the most promising thermicidal preparations of intestinal prolonged action are sesquiterpenoids isolated from plants of the Asteraceae family.American scientists from Centaurea maculosa isolated sesquiterpene lactone knicin, and from Artemisia douglasiana isolated sesquiterpene ketone vulgarone, which showed high antithermitic activity.Other authors have found that a mixture of vulgarone B and knicin due to the synergistic effect at low concentrations led to 96-100% death of termites [12,13].
The results of laboratory and field tests revealed that a number of It was found that the guaiane lactone cumambrin-A isolated from the leaves and flower baskets of Handelia trichophylla (Fig. 3) has a high thermicidal activity (Table 3).Note: d-dead termites, l -live termites.
As can be seen from Table 3, cumambrin-A has high thermicidal activity and at low concentrations (0.001 and 0.003) and on the 6th-8th days of use causes 96-100% death of termites.The test results showed that the above sesquiterpene lactones are a potential basis for the creation of effective antithermitic preparations.The areas and reserves of plant raw materials make it possible to fully meet the need for biologically active lactones to create highly effective thermicidal preparations.

Conclusions
Based on the above data, it can be concluded that the search for plants containing biologically active terpenoids, the expansion and deepening of scientific and applied research in this direction, will lead to the creation of new highly effective ones environmentally friendly natural pesticides, and this in turn leads to the rational use of local plant raw materials, environmental protection, which indicates the relevance and prospects of research in this direction.

Table 1 .
Determination of seed germination in the field.

Table 2 .
Indicators of rice yield in the field.