Effect of economic value characteristics of newly created mulberry varieties on biological indicators of silkworm

. The demand for natural fibers on the global market and the ongoing improvement of coir product quality indicators need the efficient use of scientific advancements and creative ideas in their production. In the development of mulberry varieties and hybrids, which are used as food for silkworms, it is particularly crucial to employ new, promising types with high economic value, chemical composition, and nutritional value, as well as those that are resistant to various external stress factors. The growing demand for natural fibers in the global market and the need for better quality coir products necessitates the efficient utilization of scientific advancements and innovative techniques in their cultivation. During the experiment, 4 plants of each mulberry variety were selected and 30 pieces of leaves were picked from their different parts. Immediately, the total length, width and leaf band of each of them were measured, and the length was determined. The results showed that the moisture content of leaves in the spring season showed the highest result in the Markhamat-2017 variety - 7.20%. This indicator was equal to 7.07-7.02% in Mustaqillik-2018 and Jarariq-12 varieties. It was found to be equal to 7.04% in the comparative Tajikskaya bessemyannaya mulberry variety. In the summer season, the amount of moisture in the leaf was 6.96-7.22% in mulberry varieties.


Introduction
The increasing attention to natural fibers in the world market, the further improvement of the quality indicators of the coir products, requires the effective use of scientific achievements and innovative innovations in their cultivation [1][2][3][4][5]. It is especially important to use new promising varieties with high economic value, chemical composition and nutritional value, resistant to various external stress factors, in the breeding of mulberry varieties and hybrids, which are considered silkworm food [1][2][3][4].
To date, many varieties of mulberry, resistant to the natural climate of our country, resistant to the natural climate of our country, with high economic characteristics and high leaf productivity, have been propagated vegetatively, that is, by grafting, in the farms specializing in mulberry growing in the regions of our republic. is being introduced to the conditions. This, in turn, ensures an increase in the quality and quantity of cocoon raw materials [4][5][6][7].
The fodder base of sericulture in Uzbekistan mainly consists of single rows of mulberry trees and mulberry trees. By now, the existing mulberry plantations in the republic are 54,000.0 hectares and single-row mulberry trees are more than 140.0 million. Compared to tall tussocks, tussocks planted in the form of a bush are exploited earlier and their leaves can be used. Currently, hybrid seedlings and one-year seedlings are used to create a bush [4][5][6][7][8].
In the spring , summer and autumn seasons, a number of works have been carried out by foreign and local scientists in the direction of creating new mulberry varieties.
In order to create a strong food base for silkworms in our republic, the main task of the present day is to multiply mulberry groves and single row mulberry trees at the expense of high-quality, high-yielding variety and hybrid mulberry trees [4]. In addition to silkworm agrotechnics, anatomy and morphology, genetics, selection, scientific research has been conducted in the direction of mulberry selection and positive results have been achieved. As a result, varieties such as Jarariq-2, Jarariq-4 and Jarariq-5 have been created and introduced into production [3].
The article describes various studies conducted on different breeds of mulberry silkworms during the summer and autumn seasons. The studies evaluated the reproductive and biological characteristics of breeds such as Orzu, Asaka, Gozal, Marhamat, Yulduz, Gulshan, Marvarid, and Nafiz, as well as their hybrids. One study focused on the productivity, morphological, and technological characteristics of the cocoons produced by the (F2) generation of silkworms reared in unfavorable natural climatic conditions [8][9][10]. Another study investigated the morphological characteristics of newly selected mulberry numbers #2-02, #3-02, #4-02, #5-02, and #7-02, and their effect on the growth dynamics of silkworm larvae.

Materials and methods
Research work was carried out and observed in the "Mulberry Breeding and Agrotechnics" and "Mulberry Silkworm Breeding, Ecology and Prevention of Chemical Poisoning" laboratories of the Silk Research Institute, as well as in the fields of the Jararik Experimental Farm of the institute. During the conducted experiments, the leaf level and weight of the mulberry Markhamat-2017, Mustaqillik-2018, Jarariq-12 and comparative Tajikskaya bezsemyannaya varieties were determined twice per a year. The first experimental measurements were organized on May 10-15 [1][2][3][4][5]. The second measurement was carried out in the summer on August 10-15. Clearly, 4 plants of each mulberry variety were selected and 30 pieces of leaves were picked from their different parts. Immediately, the total length, width and leaf band of each of them were measured, and the length was determined [6][7][8].
After measuring the weight of the leaves, their level was measured sequentially on an electronic scale, first with the leaf band and then separately. Net leaf weight was determined by subtracting the leaf band from the actual leaf weight ( Fig. 1 and 2). Based on this, morphological characteristics of new varieties were studied and their rating indicators were determined [1,[4][5][6][7][8].
In the research conducted in the second direction, in the spring and summer seasons of 2021, the composition of chemical substances per 100 g of dry matter of the leaves of new promising mulberry varieties and comparative varieties was comparatively studied in special laboratory conditions [4][5][6][7][8].
Markhamat-2017, Mustakillik-2018, Jarariq-12 and comparative Tadjikskaya bessemyannaya varieties placed in the special orchards of the Jarariq experimental farm under the authority of the Silk Industry Research Institute, planned in the middle of the 5th year of the worms during the spring and summer worm feeding period. Sufficient leaf samples were taken to obtain dry leaves from mulberry cultivars [4][5][6][7][8][9]. 100 гTotal moisture was determined based on the difference between the initial weight of the leaf and the weight in the fully dried state, and the amount of main nutrients such as crude ash, ßsitosterol, polyprenols and vitamin E was determined in a certified special laboratory of the Institute of Plant Substances Chemistry of the Academy of Sciences of Uzbekistan [8][9][10].  During the conducted research, mulberry silkworms with leaves of Markhamat-2017, Mustakillik-2018, Jarariq-12 and Tajikskaya bessemyannaya varieties were collected from worms of the "Line 27", "Line 28", "Line 101" and "Line 205" systems in the spring season. maintained in 3 returns per piece [1][2][3][4]. The same hygrothermal conditions are provided in the experimental variants, and the worms in the experimental variants are fed with leaves of the same variety from the first day of the 1st age to the last day of the 5th age.
Biological indicators of silkworms of mulberry varieties are determined: -revival of eggs; -viability of worms, %; -disease percentage, %; Clearly, after 7 days after the worms have cocooned, ready cocoons are picked, cocoons are kept at normal temperature for another 2 days, and then cocoons are divided into healthy, double and deaf cocoons [4,[6][7][8]. According to the ratio between the total number of healthy cocoons and the total number of worms, the indicator of the percentage of disease in terms of the viability of worms and the percentage of deaf cocoons is determined (Fig. 3).

Results and discussion
The main goal of the research is to determine the morphological and economic value of new varieties of mulberry, as well as the amount of chemical substances in the leaves. It was taken into account that the new varieties of mulberry, Markhamat-2017, Mustaqillik-2018 and Jarariq-12, are widely introduced in the republic today. Important characteristics of mulberry cultivars: leaf level (length, width, band size), leaf weight (with leaf band, band, net weight of leaf) indicators were comparatively analyzed in each variety. It is known that if the leaf surface is heavy, the nutritional value of the leaf is high. The 2021 experiments on leaf area and leaf weight of mulberry cultivars are presented in Table 1. 18.7 cm in Markhamat-2017 variety, 23.3 x 18.0 cm in Mustaqillik-2018 mulberry variety, and 20.0 x 17.1 in Jarariq-12 variety. cm, and in our comparative variety it was 16.9 x 13.4 cm. The length of the leaf band increased from 4.5 cm to 6.1 cm. It was observed that the highest index of weight with leaf band was 8.2 g in Markhamat-2017 variety, 6.3 g in Mustaqillik-2018 mulberry variety, 6.0 g in Jarariq-12 variety and 4.5 g in our control variant. The lowest value of leaf net weight was 4.0 g in the reference variety, 5.0 -5.6 g in the Mustaqillik-2018 and Jarariq-12 mulberry varieties, and 7.7 g in the Markhamat-2017 variety.
In the conducted scientific research, it can be observed that among the mulberry varieties being tested in the spring and summer seasons, the highest rate was found to be Markhamat-2017 and Mustaqillik-2018. The Jarariq-12 variety was next, which was found to be superior to the comparative Tajikskaya bessemyannaya variety. The main goal of the second direction of research is to study the chemical composition of the leaves of new promising mulberry varieties. The amount of chemical substances in the leaves of the selected mulberry Markhamat-2017, Mustaqillik-2018, Jarariq-12 and comparative varieties was determined in a special certified laboratory of the Institute of Plant Substances Chemistry of the UzFA. The data are presented in Table 2. According to the data presented in Table 2, the moisture content of leaves in the spring season showed the highest result in the Markhamat-2017 variety -7.20%. This indicator was equal to 7.07-7.02% in Mustaqillik-2018 and Jarariq-12 varieties. It was found to be equal to 7.04% in the comparative Tajikskaya bessemyannaya mulberry variety. In the summer season, the amount of moisture in the leaf was 6.96-7.22% in mulberry varieties. The amount of ash in the leaves was 9.96-12.63% in spring and 10.37-14.26% in summer. Among the vitamins in the leaf, vitamin E also has a positive effect on the growth and development of the silkworm. It was observed that vitamin-E was equal to 0.005-0.006% in spring and 0.007-0.008% in summer season in mulberry leaves. The text describes a research study that analyzed the impact of new mulberry cultivars on the biological characteristics of silkworms over a period of 2020-2022. The study is presented in Table 3 and the histograms shown in Figure 4, which depict the results of maintaining "Line-27", "Line-28", "Line-101", and "Line-205" systems using different mulberry varieties such as Markhamat-2017, Mustakillik-2018, Jararik-12, and Tajikskaya bessemyannaya.
When comparing the numbers from Table 3, it was found that there was an influence of mulberry varieties on these important vital indicators. The indicator of egg survival in "Line-27" and "Line-28" systems fed with the Markhamat-2017 variety is 97.0%, 92.0%, 93.0%, 95%, 97.0% and 98.0% in 2020-2022. It was observed that the seeds treated with the Markhamat-2017 variety were revived by 2.0-3.0% more than the ordinary variety (Table 3). It is known how important the viability of worms is, that's why this biological indicator was in our attention. In the comparative common variety Tadjikskaya bessemyannaya variety, this indicator was shown in the range of 81.2-86.4% over the years, while in the other 3 new varieties, the results were obtained from 84.0% to 93.1%. If we pay close attention to the three-year averages, we are fully convinced that egg survival can be increased to 96.0% and worm viability can be increased to 92.3% of the brood reared with new mulberry cultivars. It should be emphasized that the number of worms maintained at 92.3%, which is characteristic of hybrid worms, is considered a very high result for breeding systems. These thoughts are fully confirmed by the incidence of worms. Because the "Line-28" system's morbidity rate was reduced by 1.67% depending on the type of feed (Fig. 4). In the assessment of mulberry varieties based on the biological indicators of silkworms, the percentage of incidence of silkworms is not less important. Because sterile and high agrotechnical conditions are not always provided during worm feeding in production conditions. Then silkworm immunity and leaf quality become the only factors. It may happen that the worms grow and develop well for 5 years, but when the period of cocooning comes, due to a decrease in the size or quality of the food, the worms die without cocooning or turning into a tuber. As a result, deaf, black, and white cocoons multiply and significantly damage the productivity of cocoons. We believe that if the mulberry silkworm is fed with full and high quality leaf, the diseases mentioned above can be reduced and cocoon yield can be significantly increased. In this direction, the percentage of worm infestation in silkworm systems maintained with the Markhamat-2017 variety has been proven to be much lower than in the variants maintained with other varieties. If we compare the numbers directly, we can see that the disease percentage was 0.90-5.3% when the "Line-27", "Line-28", "Line-101", "Line-205" systems were treated with the leaves of the Markhamat-2017 variety. This indicator was 1.85-6.12% when cultivated with Tajikskaya bessemyannaya variety. It can be observed that the leaves of other varieties are more effective than the comparator and have a positive effect on worms.