Using the dominance coefficient in assessing cotton families

. Optimization of the cotton breeding process at the present stage is the main condition for the success of practical breeding. The need for continuous change and improvement of varieties, as well as a reduction in the timing of their breeding, requires a revision of the arsenal of breeding methods and many theoretical attitudes from the point of view of the ideas of modern genetics. The ideas of statistical genetics are especially effective for the development of the theory and methods of selection, as well as its central link - the theory of selection and selection of parental pairs. In practical terms, they make it possible to develop the most accurate criteria for the selection, selection and evaluation of breeding material, and this is the main content of optimization of the breeding process. Even in the strictest self-pollinators, although rarely, the plants are re-pollinated or, in any case, are capable of re-pollinating. Consequently, plants can exchange genetic material, transmit the emerging hereditary changes to each other, and it can be considered as a potential population. This article presents the results of studies to study the possibility of using the dominance coefficient when assessing cotton families. It was shown that phenotypically homogeneous families when crossing show different degrees of manifestation of the studied traits in F1 hybrids.


Introduction
The experiment can serve as a model of the processes occurring in populations of distantly hybrid varieties and introgressive lines of cotton under the influence of natural crossing, which, according to the literature, varies from 5 to 27 percent and averages 15 percent per population [3].The heterozygous hybrid genotypes obtained from the cross, already with F1, exhibiting the introduced valuable traits of diploid wild species, become intrapopulation sources of cross, producing up to half of the low-value genotypes in F2; heterozygous and low-value (devoid of introduced valuable traits) homozygous genotypes cleaved in subsequent generations also become sources of intrapopulation overlap.In this situation, a chain process of spontaneous emission of introduced genetic traits of diploid wild species is launched, which in subsequent generations becomes an avalanche-like character.
As a result, the varieties created by the method of distant interspecific hybridization, over the course of several years, disintegrate into populations represented by low-value genotypes.
Kyazimov and Sadykova [2] note that the problem of the purity of varieties is one of the most urgent and, even it can be said, intractable.One of the reasons for the genetic degradability of varieties is an unfinished formative process.It is necessary to develop a new theoretically substantiated methodology for finalizing new varieties of cotton, aimed at preserving their original characteristics.
The most common methods for assessing combinative ability are topcross and diallele crossing.In recent years, incomplete, intermittent controlled crosses, factorial, cluster, discriminatory methods of analysis have been proposed, differing in the number of required relationships, testing of hybrids, and the accuracy of the data obtained.All these methods require a large number of crosses in order to determine the economic indicators according to the crossing schemes [8,9].
In the practice of breeding work, it is necessary to take measures to improve the accuracy of assessing families.Correct assessment of breeding materials will allow for timely selection and transfer to extended and competitive variety testing of reliably the best in productivity and genetically homogeneous families.The laboriousness of statistical processing of materials is insignificant and the costs will be fully paid off by reducing the breeding cycle and increasing the efficiency of breeding, transferring varieties to the State Test and preliminary breeding, the high productivity of which has been reliably proven and genetically fixed.
In this regard, the increase in the accuracy of the assessment of breeding materials, achieved with the help of genetic and statistical methods, is now of particular importance.The goal of our work is to create phenotypically homogeneous families identical in terms of the tested morpho-economic characteristics, to study them and, on the basis of geneticstatistical methods, to develop a method for creating effective cotton varieties with high uniformity and adaptation to environmental conditions.

Materials and methods
Studies were carried out at Research Institute of Cotton Breeding of Uzbekistan, where they studied F1 hybrids obtained according to the dialle pattern of crosses between families C-1, C-2, C-3, C-4, C-5 lines L-93 belonging to the species G. hirsutum.
Sowing was carried out according to the scheme 60x30-1.The agrotechnics adopted in the Research Institute of Cotton Breeding of Uzbekistan was used.Statistical processing of the obtained digital material was carried out according to Dospekhov [1].The dominance indicator was determined by Beil and Atkins [4].

Results and discussion
Table 1 shows the indicators of the mass of raw cotton 1 box and the length of the fiber in families and hybrids F1.It can be seen from the above data that the weight of raw cotton for 1 box in the studied families was 5.85-6.38 g and did not have large differences in comparison with the indicators of this trait in F1 hybrids 5.68-6.59g.
The studies used families with typical morphology for L-93 and indicators of economically valuable traits.As can be seen from the data given in Table 1, the indices of the mass of raw cotton 1 boll in most cases did not have significant differences both between families and hybrid combinations, and between hybrid combinations.In this regard, it is of some interest to study the indicators of the dominance of these characters.The results are well illustrated in Figures 1 and 2. Figure 1 shows a histogram of indicators of the dominance of the mass of raw cotton 1 box in F1 hybrids.
From the given bar chart (Figure 1), it can be seen that in 7 cases a negative value of dominance indicators was obtained, deterioration of the average indicators of the trait.In 3 cases, in the combinations C-2xC-1, C-1xC-4, C-2xC-4, negative heterosis was obtained with values from -1.2 to -6.7.In families C-3xC-1, C-5xC-1, C-1xC-2, incomplete dominance of the large-boxed parent was noted, in families C-4xC-1, C-3xC-2, C-4xC-2, C-3xC-1, C-4xC-3, C-3xC-4, C-5xC-4, positive heterosis was observed with values from 2.2 to 6.1.Positive heterosis was observed in direct and reverse combinations of crosses of families C-3xC-1, C-1xC-3 and C-3xC-4, C-4xC-3.Of the studied 20 combinations of crosses 13 combinations had incomplete dominance and positive heterosis of the mass of raw cotton of one box.When family No. 2 was used as the maternal form, in most cases there was a decrease in indicators in comparison with the parental forms.When using this family as the paternal form, the dominance of the large-boxed parent was noted [5]. Figure 2 shows a histogram of fiber length dominance indices in F1 hybrids.The histogram shows that along the length of the fiber, a different picture is observed than according to the sign of the mass of raw cotton of one box.Here, only in 3 combinations of crosses negative values of the dominance coefficient C-1xC-3, C-2xC-1, C-2xC-4 were obtained.In 5 combinations of hybrids, incomplete dominance of the large-boxed parent was observed, and in 12 combinations of hybrids, positive heterosis was noted with values from 1.5 to 27.7.The best result was obtained in combinations with the participation of the C-5 family, with a positive result obtained in direct and reverse combinations.These are hybrid combinations C-5xC-1, C-1xC-5, C-5xC-2, C-2xC-5, C-5xC-3, C-3xC-5, C-5xC-4, and C-4xC-5.It can be assumed that the crossing between plants of these families will not contribute to the deterioration of the fiber length indicator [6].The indicators of the dominance of the number of sympodial branches were associated with combinations of hybrids; the influence of the reciprocal effect was also noted on the manifestation of this trait.The reciprocal effect was not observed on the homeostaticity indices of this trait.The highest ACS was observed in the O-3 family, while the O-2 and O-4 families had ACS with negative values.When comparing variance effects of general and specific combining ability, it was found that for most genotypes Gsi 2 > Ggi 2 , i.e. nonadditive effects have a stronger effect on the manifestation of the trait in F1 hybrids than additive effects.
In most of the studied hybrid combinations, according to the number of bolls formed on 1 bush, positive incomplete dominance and heterosis were noted, as well as the influence of the reciprocal effect on the manifestation of this trait.The highest homeostaticity indices were observed in hybrid combinations obtained with the participation of families O-  In 2 of the studied 5 families of the T-93 line, according to its weight of raw cotton of one boll was noted dominancy, and the reciprocal effect was not observed on the homeostatic indicators (Figure 3).ACS indices in families O-1 and O-2 were negative, and the highest ACS was observed in O-5 families.When comparing variance effects of the general and specific combining ability in the O-5 family, it was found that in the O-5 family Gsi 2 > Ggi 2 , i.e. on the manifestation of the trait of the mass of raw cotton for one boll, additive effects have a stronger influence.The relationship between the quantity of the ACS and average indicators of the mass of raw cotton of one boll is noted.In most of the hybrid combinations, it was noted that the dispersion of fiber yield was slightly higher than the indicators of families, and in 13 hybrid combinations out of 20 negative incomplete dominance or heterosis was noted.The influence of the reciprocal effect on homeostaticity indices was not observed.ACS indices in families O-1 and O-5 had a positive degree, and the highest degrees of the average and ACS indices were observed in families O-1.The O-4 family also had a high average index, but the ACS was low and had a negative degree.When comparing variance effects of general and specific combining ability in families O-1, O-2 and O-5, it was found that Gsi 2 > Ggi 2 , i.e. additive effects have a stronger influence on the development of the fiber length trait.
In the majority of hybrid combinations, the indices of dispersion of the mass of 1000 seeds were slightly lower than in families, and the reciprocal effect was not observed on the indices of dominance and homeostaticity.The highest ACS rates were observed in families O-2 and O-4, and despite the fact that the average indicators of the trait in the O-4 family were lower compared to other families, it had a high ACS rate.When comparing variance effects of specific and general combining ability in families O-1, O-2 and O-5, it was noted that Gsi 2 < Ggi 2 , i.e. additive effects have a stronger effect on the formation of the fiber length trait.When comparing variance effects of general and specific combining capacity, it was found that Gsi 2 > Ggi 2 , i.e. non-additive effects have a stronger influence on the development of the trait for mass of 1000 seeds.
The majority of hybrid combinations for fiber microneir showed negative heterosis and the reciprocal effect was not observed on the homeostaticity indicators of this trait.Most hybrid combinations have fiber lengths of 1.19-1.23 inches, which meets the requirements for a fourth fiber type.There was no significant effect of the reciprocal effect on the dispersion and homeostatic properties of fiber length.

Conclusions
In conclusion, a similar pattern was observed in terms of the specific breaking load of the fiber.Here, too, there was no significant effect of the reciprocal effect on the dispersion and homeostatic properties of the specific breaking load of the fiber.The best families, united into one cluster, created the genetic core of the TSAU-100 variety, which has the best and stable economically valuable traits, where the negative relationships between traits are most leveled.
In most hybrid combinations, incomplete dominance and positive heterosis of the raw cotton mass of one box were noted.When family No. 2 was used as the maternal form, in most cases there was a decrease in the mass of raw cotton 1 box, and the dominance of the large-box parent was noted as the paternal form.In combinations with the participation of the C-5 family, a positive result was observed, both in direct and inverse combinations.

Figure 1 .
Figure 1.Indicators of the dominance of the mass of raw cotton 1 box in F1 hybrids.

5 E3SFigure 2 .
Figure 2. Dominance indicators of fiber length in F1 hybrids.The data on the hybridological analysis of 5 families of the breeding line L-93, acquired by the backcross plants of the hybrid population of older generations (F13 [(F1 B1 C-5619) x (F1 C-5619 x 397503)] x L-06), obtained from crossing sample under catalog number 397503 ssp.yucatanense from the collection of Research Institute of Cotton Breeding of Uzbekistan with local varieties, and hybrids between 5 families obtained by crossing according to the dialle pattern.In most of the studied hybrid combinations, the mean indices of the number of sympodial branches were lower in comparison with families O-1 and O-3.Most of the studied hybrid combinations of this trait showed positive and negative heterosis.The indicators of the dominance of the number of sympodial branches were associated with combinations of hybrids; the influence of the reciprocal effect was also noted on the manifestation of this trait.The reciprocal effect was not observed on the homeostaticity indices of this trait.The highest ACS was observed in the O-3 family, while the O-2 and O-4 families had ACS with negative values.When comparing variance effects of general and specific combining ability, it was found that for most genotypes Gsi 2 > Ggi 2 , i.e. nonadditive effects have a stronger effect on the manifestation of the trait in F1 hybrids than additive effects.In most of the studied hybrid combinations, according to the number of bolls formed on 1 bush, positive incomplete dominance and heterosis were noted, as well as the influence of the reciprocal effect on the manifestation of this trait.The highest homeostaticity indices were observed in hybrid combinations obtained with the participation of families O-1, O-3, and O-5.The O-5 family had the highest ACS and Ggi 2 variance; in other hybrid

5 E3S
Web of Conferences 381, 01014 (2023) https://doi.org/10.1051/e3sconf/202338101014AQUACULTURE 2022 combinations these indicators were much lower.ACS indices in families O-2 and O-4 were negative.When comparing variance effects of specific and general combining ability, it was identified that in the O-5 family Gsi 2 > Ggi 2 , i.e. additive effects have a stronger effect on the control of this trait.

Figure 3 .
Figure 3. Indicators of ACS and SCS of the number for bolls formed on 1 bush in families of the T-93 line.The fiber length in hybrid combinations was in the range of 34.3-36.2mm and was equal or slightly lower than that indices of families.A significant influence of the reciprocal effect was observed on the development of this feature.The homeostaticity indices did not depend on how the family was taken into hybridization as a maternal or paternal form.ACS indicators in families O-3 and O-5 were the highest and were associated with the average indicators of this trait.When comparing variance effects of general and specific combining ability in families O-2 and O-5, it was found that Gsi 2 > Ggi 2 , i.e. additive effects have a stronger influence on the formation of the fiber length trait.

Table 1 .
Indicators of raw cotton mass and fiber length in families and hybrids F1.
1, O-3, and O-5.The O-5 family had the highest ACS and Ggi 2 variance; in other hybrid