Study of rice genotypes and their use in the process of selection

. This research was aimed the use of non-traditional, biochemical marker-based selection methods in synchronization with classical methods in rice selection, rapid adaptation to adverse environmental factors, disease tolerance, lodging and shedding resistance, high yield and technological quality of rice. According to the results of the experiment, 42 varieties in 2018, 28 in 2019 and 39 in 2020 with a total of 109 combinations of 7172 flowers were selected with the participation of varieties and specimens that are resistant to various environmental influences and diseases, high yield, high grain quality. was carried out. The results of the hybridization showed that 118 (or 3.78%) in 2018, 117 (or 5.35%) in 2019, 81 (or 4.35%) in 2020, a total of 316 (or 4.4%) hybrid populations were taken. F 1 generation hybrids obtained from the combinations of Chongwang x TShD 15-13 and Chongwang x 227-09, was recommended not to use these combinations in future studies due to the low dominance of “Ruvak” (paniculo is a type of plant inflorescence) length and 1000 grain weight.


Introduction
Rice is the most important food crop in the world, the second largest in terms of area under cultivation in the world, and the first in terms of yield among cereals [1]. According to the U.S. Department of Agriculture (USDA), in 2018, 765.6 million tons of rice were grown. In particular, 224.6 million tons of rice were harvest in China, followed by 176.9 million tons in India, 56.1 million tons in Indonesia, 54.6 million tons in Bangladesh, 43.5 million tons in Vietnam, 31.5 million tons in Thailand 20.5 million tons in Burma, 18.4 million tons in the Philippines, 12 million tons in Japan and 11.5 million tons in Pakistan [2]. In order to ensure food security in a number of developed rice-growing countries of the world, grain quality has been improved and high yields and economic efficiency has been achieved through the creation, selection, rational placement of varieties suitable for soil and climatic conditions, scientifically based application of advanced resource-saving technologies.
Today, about 450,000 tons of rice have been harvested from about 115,000 hectares of agricultural land in Uzbekistan, and the average amount of rice per capita was 7.6 kilograms. However, this did not meet with demand of the state population for rice, consequently, in 2019, 58.7 thousand tons of rice products were imported from foreign countries. In recent years, comprehensive reforms have been carried out in the country to develop agriculture. In particular, the Resolution of the Cabinet of Ministers of the Republic of Uzbekistan dated December 12, 2019 No. 986 "On additional measures for the development of rice" was adopted. Accordingly, the Karakalpak Scientific Experimental Station of the Rice Research Institute, rice clusters, the Association "Uzbeksholichilik" was established. The ongoing reforms are aimed at increasing rice production in the country, stable supply of the domestic consumer market with rice products and increasing export potential. For this, the rational use of land and water resources, the creation, selection of new varieties of agricultural crops adapted to local soil and climatic conditions, serious attention has to consider the introduction of resource-saving modern agro-technologies. In this regard, to conduct research on the development and introduction of new varieties of rice with high quality, resistant to adverse environmental conditions, diseases and pests, is vitally important towards increasing productivity in rice cultivation, improving grain quality and meeting the demand of the population for rice products [1][2][3]5].
The selection process can be carried out in traditional classical or non-traditional selection methods, and its success depends on the effectiveness of the selection methods. Based on the traditional selection methods in use, breeders have the ability to distinguish only ridges with certain genotypes from hybrid populations. All varieties of rice grown in the country are based on traditional (classical) selection methods, based on the ability of selection scientists to select genotypes that combine morphological and physiological characteristics [4]. The traditional selection process is a 10-12-year process consisting of painstaking research involving multiple selections, tests in different climatic conditions [4,6]. Therefore, the changing soil and climatic conditions and the corresponding changes in requirements require the use of non-traditional methods and technologies that would help to accelerate the creation of new varieties. Therefore, in today's plant selection, the development of selection in cultivated plants on the basis of non-traditional methods, and the study of indicators controlled by individual genes or groups of genes based on modern biochemical markers are developing [4,5]. Molecular modern biochemical markers (MAS) technologies of biology play a special role in determining the level of salinity resistance of plants. Because protein molecules in a plant cell are an unchanging quality indicator [5][6][7][8]. Based on the above-mentioned points, this research was aimed the use of non-traditional, biochemical marker-based selection methods in synchronization with classical methods in rice selection, rapid adaptation to adverse environmental factors, disease tolerance, lodging and shedding resistance, high yield and technological quality of rice. Accordingly, following research objectives were formulated: 1) study, evaluation and selection of varietal samples, hybrids and ridges as primary sources, valuable economic characteristics, adaptability to adverse environmental factors and disease resistance, 2) mixing of selected parent pairs, and 3) evaluation and selection of valuable economic traits in hybrid populations, characteristics of adaptability to adverse environmental factors, disease immunity, resistance to lodging and shedding [3][4][5][6].

Materials and methods
The research was conducted in the experimental fields of the Rice Research Institute, that was, in 2018 and 2020 on an area of 1.30 hectares on the 3rd edge of 12 cards, and on 1.07 hectares area on the 2nd edge of 13 cards in 2019. The experimental fields of the Institute are located in the south-eastern part of the Tashkent region, on the left bank of the Chirchik River, and geographical location is 41°11'16 "north latitude and 69°20'07" east longitude ( Figure 1). The topography of the area was flat, the soil layer in the experimental fields encompassed gray meadow and meadow swampy soils. The driving layer was 0-30 and 0-40 cm, below the driving layer was a layer of gel 30-40 cm thick, at a depth of 60-70 cm there was a layer of sand and small stones. The sandy and fine-grained layer was also found at 30-40 cm in some parts of the experimental area. Moreover, the amount of physical mud of soil in 0-30 cm depth was 51.9%, followed by pH amount accounted for 7.3 (Table 1). There were no mineral salts due to the fact that the soils of the experimental area were composed of sand and gravel, and the groundwater flows from the northeast to the southwest. In the same soil depth, the amount of humus was 1.86%, Nitrogen N-NO3 mg/kg was 22.4, Phosphorus P2O5 mg/kg was 84, and Potassium K2O mg/kg was 17.6 ( Table 2). Air temperature and relative humidity vary in different years. These meteorological factors have a significant impact on the growth and development of rice, as well as other agricultural crops. According to long-term data from the Tuyaboguz meteorological station, the average air temperature during the year was 12.3 °C, and the highest air temperature in July was +34.5 °C degrees. The coldest temperature was minus 6-8 °C in January, and in some years, and it was dropped to minus 10-15 °C, but winter rarely comes cold [5,6].
Field experiments were conducted based on the methodology of the All-Russian Rice Research Institute, whereas statistical analysis of the results was obtained using the method of B.A. Dospekhov [5]. Phenological observations were carried out in accordance with the manual "State Variety Testing of Agricultural Crops". During the period from germination to full ripening of the rice plant (harvesting, pruning, rooting, flowering and ripening), it was observed that all crops undergo the same developmental phases at the same time [9,10]. At the end of the growing season, before harvest, in order to determine the biometric parameters, biometric analysis was carried out in the laboratory under sample conditions from 1 m 2 area at 3 points of each plot. In this case, parameters were plant height, number of productive stems, length of the plate, the number of grains in the husk, including the number of whole and empty grains, grain weight per grain, 1000 grain weight, and accumulatio rate. The crop in each plot was harvested to determine the yield. The quality of the grain was determined in a special laboratory. The grain size of the ridges in the varietal selection test was determined by the measurement method. In this case, 15 grains of each ridge were taken and a series was analyzed, and the total length, width and thickness were measured. The result was divided by 15 to determine the average grain, rice length, width, and thickness [10].
As a standard, 425 cultivars were planted in the collection nursery in 2018-2020. Phenological observations were made on the planted cultivars and the phases of germination, accumulation, tubing, flowering and ripening were determined. Plant height was important in creating new varieties of rice. Therefore, the morphology of the cultivars was initially studied on the basis of plant height [9,10]. Accordingly, all cultivars were divided into 5 groups: low-growing (65-84 cm) specimens, medium-sized (85-104 cm) specimens, medium-tall (105-124 cm), long-stemmed (125-144 cm), and very. classified into tall (above 145 cm) specimens. Twenty-two specimens were included in the group of low-height specimens, 43 in the group of medium-height specimens, 96 in the group of medium-length specimens, 223 in the group of tall specimens, and 41 in the group of very tall specimens (Figure 2).  The dominance of plant height, stalk length, and grain weight per 1000 grains in the F1 generation hybrid combinations studied was determined by the following formula: Where: hp is the dominance level F is the arithmetic mean of the hybrid R is thearithmetic mean of theparent form with a high value Mr is the parent arithmetic mean of shapes [5] 3 Results and discussion

Mixing and hybrid seedlings
When selective scientists create varieties suitable for each region, it is important to select the right target genotypes and parental forms for crossbreeding, which are mainly high-yielding. Heterosis is most pronounced in their hybrids when the parental forms are biologically and genetically different. As a result of hybridization of rice varieties that are geographically distant, the basis for the emergence of genetically productive hybrids formed in different places in the plant genetics, which in themselves reflect the characteristics of the parent forms that appear in different environmental conditions. The most important thing in selection is a specific genotype or homo-heterozygous and other indicators of fertility, i.e., what genetic potential it has. This is due to the problem of selecting excellent genotypes from hybrid mixtures when hybridizing two factors. During the years of the project, local and foreign varieties recommended for use as parental forms  were planted in the growing area. In this case, they were planted in 3 periods, synchronizing flowering periods with each other.
The rice plant was fed with mineral fertilizers and carefully cared for in the water regime for good growth and development. With the onset of the flowering phase, interbreeding was carried out in the furrows, which are suitable for the best developed plants. According to the results of the experiment, 42 varieties in 2018, 28 in 2019 and 39 in 2020 with a total of 109 combinations of 7172 flowers were selected with the participation of varieties and specimens that are resistant to various environmental influences and diseases, high yield, high grain quality. was carried out. According to the results of the hybridization, 118 (or 3.78%) in 2018, 117 (or 5.35%) in 2019, 81 (or 4.35%) in 2020, a total of 316 (or 4.4%) hybrid populations were obtained (Table 3).

53.
Chongwan TSHD 15-13-1-1- Seeds of F1 hybrid population obtained as a result of crossbreeding were planted and maintained. Clearly, they were collected in a thermostat at 27 ºC for 7 days in the laboratory (Figure 8), and the harvested plants were transferred to paper pots filled with fine soil and kept for 15 days, 3. When the plants had 2-3 leaves, they were planted in the field and cared for side by side with the parent forms. Seeds of 4 F2, 75 F3-F6 generation hybrid populations and 17 individual selection seeds were sown in 6 rows per 2 m 2 area at a rate of 500 seeds/m 2 . Phenological and morphological observations were made at all phases of the growing season (germination, accumulation, tubing, flowering and ripening) of hybrid populations using the Pedigree method. The hybrid lines were planted in the first year together with the parent form and the characteristics were compared and evaluated. In the second and subsequent generations of the hybrid generations, work continued on the selection of lines with valuable character traits.
The observation results showed that 20 hybrids from F2 generation hybrid populations, 29 hybrids from F3 -F7 generation hybrid populations, a total of 49 hybrids were selected on morphological and biometric indicators and identified for use in selection work in subsequent years. The dominance of plant height, stalk length, and grain weight per 1000 grains in the F1 generation hybrid combinations studied was determined. The plant height in F1 generation hybrids was 104.3-132 cm, with a low level of dominance in Chongwang x 227-09 and Polizesti x Alexander combinations, and a high level of dominance in TShD 15-13 x Iskandar and Sanam x Iskandar combinations. In F1 generation hybrids, the stalk length was 18.2-23.4 cm, with a low degree of dominance in the combinations Chongwang x TShD 15-13 and Chongwang x 227-09, and a high degree of dominance in the  combinations TShD 15-13 x Iskandar and Sitora x Iskandar was observed. In F1 generation hybrids, the grain weight per 1000 grains was 27.9-34.8 g, with a low degree of dominance in the combinations of Chongwang x TShD 15-13, Chongwang x 227-09 and Polizesti x Iskandar, Sitora x TShD 20-13 and Nukus-In the 2 x Alexander combinations, a higher degree of dominance was observed. In F1 generation hybrids obtained from combinations of Chongwang x TShD 15-13 and Chongwang x 227-09, it was recommended not to use these combinations in future studies due to the low dominance of rye length and 1000 grain weight (Table 4). TSHD15-13 х Sanam addition, of the 30 selected varieties per 1000 grain weight from the ultra-early group k-243 (30.5 g), k-270 (32.8 g) and k-297 (35.2 g), from the early-maturing group k -268 (33.4 g), k-231 (34.7 g) and k-82 (32.3 g), from the middle-aged group k-43 (34.5 g), k-223 (33.9 g) and k-389 (36.1 g) and k-103 (35.5 g) from the late ripening group, were selected. The results represented that 4217 varieties in 2018, 28 varieties in 2019 and 39 varieties in 2020 with a total of 109 combinations were selected with the participation of selected varieties and specimens that were resistant to various environmental influences and diseases, high yield, high grain quality. According to the results of the hybridization, 118 (or 3.78%) in 2018, 117 (or 5.35%) in 2019, 81 (or 4.35%) in 2020, a total of 316 (or 4.4%) hybrid populations were taken. F1 generation hybrids obtained from the combinations of Chongwang x TShD 15-13 and Chongwang x 227-09, was recommended not to use these combinations in future studies due to the low dominance of "Ruvak" (paniculo is a type of plant inflorescence) length and 1000 grain weight.