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Qulmamatova Dilafruz Erkinovna, Junior researcher,
Institute of Genetics and Plant Experimental Biology of the Academy of Sciences of the Republic of Uzbekistan Adilova Shohista Shukhrat qizi, postgraduate student, Institute of Genetics and Plant Experimental Biology of the Academy of Sciences of the Republic of Uzbekistan Baboev Saidmurat Kimsanbaevic, doctor of biological sciences, head of department, Institute of Genetics and Plant Experimental Biology of the Academy of Sciences of the Republic of Uzbekistan E-mail: sai-baboev@yandex.ru
VARIATION OF QUANTITATIVE TRAITS IN F2 HYBRIDS RECEIVED IN CROSSES OF GEOGRAPHICALLY DISTANT WHEAT FORMS
Abstract: This paper presents results of analyses of inheritance and variability of yield components in geographically distant hybrids, where one of the parents was a wheat landrace. Parameters analyzed were main stem height, spike length, number of grains per spike, 1000 kernel weight and weight of seeds in one spike. The dominant inheritance of the studied traits was identified in all reciprocal hybrid combinations where one of the parents was landrace "Kayraktash". Segregation has been observed in all hybrid combinations in the second generation, and both left-side and right-side transgression has been recorded.
Keywords: wheat, landrace, hybridization, inheritance, variability, quantitative characteristics.
Introduction: Many modern varieties ofwheat and other ferent geographical origins. Varieties "Kroshka" and "Tanya",
crops are often genetically similar and have narrow genetic widely cultivating in the Republic of Uzbekistan since 2000
base. In this connection, the sources of new diversity must year, belong to the Russian breeding, the bread wheat variety
be used in crop breeding programs. Local varieties that have "Bardosh" was selected from the collection material of CIM-
emerged on the basis of combination of natural selection and MYT (Mexico), the variety "Saykhun" belongs to the local
traditional breeding [1; 2], as a rule, have broader genetic base breeding, and the variety "Kayraktash" is one of the landraces
and therefore, can provide valuable and important character- of Uzbekistan. These varieties also differ in their biological
istics for the breeding programs [3]. They have tolerance to characteristics. Varieties "Kroshka", "Tanya" and "Saykhun"
the local stress factors [4] and stable yield. During the last are biologically winter type, and the varieties "Kayraktash"
decades studying, conservation and use of landrace of wheat and "Bardosh" - is spring type.
as a donors in the breeding process, in particular to improve The recipient varieties (Kroshka, Tanya, Saykhun and Bar-
the bakery qualities of the commercial varieties, become in- dosh) were crossed with the landrace "Kayraktash" to obtain
creasingly important. hybrid populations. Seeds of F2 hybrid populations were sown
The main features of the quantitative traits such as pro- at the end of October, at the experimental plots of the Insti-
ductivity and its elements, grain quality and resistance to tute, in the 5 meter plots. Seeds were sown separately, leaving
stresses, are their significant dependence on the environment, distance of 5 cm between them. For the structural analysis of
the large group of linked genes, and the presence of significant the traits of the spike productivity, 30 spikes from the parental
interactions of genetic and environmental factors in their for- forms and 100 randomly selected spikes from each F2 hybrid
mation [5]. Therefore, studying of the features of the forma- population were selected. Conducted analyzing of height of
tion of traits of productivity in different growing conditions the main stem and productivity elements - length of the spike
is very important for selecting of the initial material of wheat and the grain number in a spike.
in adaptive breeding [6]. Results of research and their discussion: Analyzed
Materials and methods of research: As a material of productivity components of the parental forms and hybrids
the research were selected bread wheat varieties of the dif- of the first generation and estimated inheritance of the traits
such as length of the spike, grain number in a spike, 1000 kernel weight and grain weight of a spike. Established that main yield traits in the first generation inherited dominantly and in many combinations observed heterosis. Conducted hybridologic analysis of the inheritance of these traits in the second generation. In the hybrid populations analyzed such traits as height of the main stem, length of the spike, grain number in a spike, 1000 kernel weight and grain weight in a spike of the hybrid plants, where the parents "Bardosh" and "Saykhun" were relatively resistant to wheat rust diseases, varieties "Tanya", "Kroshka" and old local variety "Kayraktash" were susceptible.
One of the widely studied quantitative traits of wheat is the height of the main stem. Creation of intensive wheat varieties led to increase in stem density and to decrease in plant height. Almost all commercial varieties cultivating in Uzbekistan are dwarf with the height not exceeding 85-90 cm. Increasing the density of the wheat stem leads to deterioration in the feed quality of the straw obtained from stems of plants.
Table 1. - Mean values of the productivity
On the other hand, the discrepancy between the spike weight and the stem density leads to lodging.
In the table-1 shown the average indexes of the parental forms and reciprocal hybrids F2. It can be seen from the table that according to the plant height, the average indexes of the hybrids in the second generation are higher in all combinations than parent forms. The average height of the main stem in the reciprocal hybrids of "Tanya x Kayraktash" is 90.78 ± ± 0.83 and 89.72 ± 0.74 cm, and in the parent forms - variety "Tanya" - 79.30 ± 0.83 cm and in the variety "Kayraktash" -85.13 ± 0.75 cm, while the coefficient of variation in the parental forms was 4.66 and 3.95, and in their F2 hybrids - 9.18 and 8.27, respectively.
The same picture could be observed in the reciprocal hybrids of "Kroshka x Kayraktash". In parent forms, the height of the main stem was 81.60 ± 0.78 cm in the variety "Kroshka" and 85.13 ± 0.75 cm in the second parent, variety "Kayraktash", and their F2 hybrids had 84.90 ± 0.67 cm and 90.56 ± 0.82 cm. 2
traits in the parental and F„ hybrid forms
Varieties and hybrids Height of the main stem. cm Spike length. cm
x ± Sx V% h2 x ± Sx V% h2
Tanya 79.30 ± 0.83 4.66 9.58 ± 0.14 6.72
Kposhka 81.60 ± 0.78 4.28 9.20 ± 0.13 6.32
Bardosh 83.30 ± 0.76 4.08 10.17 ± 0.14 6.24
Sayhun 74.00 ± 0.70 4.23 8.87 ± 0.10 4.9
Kayraktash 85.13 ± 0.75 3.95 11.48 ± 0.18 7
Tanya x Kayraktash 90.78 ± 0.83 9.18 0.83 10.86 ± 0.11 10.85 0.7
Kayraktash x Tanya 89.72 ± 0.74 8.27 0.71 11.19 ± 0.11 9.61 0.58
Kayraktash x Kposhka 84.90 ± 0.67 8.01 0.79 11.97 ± 0.09 8.27 0.68
Kposhka x Kayraktash 90.56 ± 0.82 9.13 0.84 11.18 ± 0.10 9.18 0.6
Bardosh x Kayraktash 86.08 ± 0.54 6.35 0.56 10.66 ± 0.10 9.93 0.55
Kayraktash x Bardosh 89.07 ± 0.66 7.51 0.8 11.15 ± 0.10 9.46 0.68
Bardosh x Sayhun 88.43 ± 1.10 12.47 0.9 10.33 ± 0.11 10.77 0.73
Sayhun x Bardosh 86.08 ± 1.15 13.39 0.89 10.33 ± 0.12 11.16 0.66
Varieties and hybrids Grain num ber in per spike 1000 kernel weight. g
Tanya 52.40 ± 1.14 9.76 46.60 ± 0.27 2.6
Kposhka 54.63 ± 1.06 8.71 47.54 ± 0.44 4.19
Bardosh 56.83 ± 1.25 9.85 48.83 ± 0.31 2.83
Sayhun 56.27 ± 0.98 7.75 48.74 ± 0.34 3.17
Kayraktash 52.50 ± 1.08 9.19 45.41 ± 0.39 3.89
Tanya x Kayraktash 62.82 ± 0.98 15.6 0.75 45.91 ± 0.34 7.61 0.81
Kayraktash x Tanya 59.99 ± 0.99 16.58 0.76 46.65 ± 0.37 7.96 0.7
Kayraktash x Kposhka 67.17 ± 0.77 11.51 0.53 44.84 ± 0.36 7.93 0.68
Kposhka x Kayraktash 66.40 ± 0.99 14.91 0.61 45.03 ± 0.37 8.31 0.55
Bardosh x Kayraktash 63.68 ± 1.01 15.81 0.59 42.79 ± 0.32 7.67 0.55
Kayraktash x Bardosh 62.49 ± 0.95 15.24 0.6 45.07 ± 0.77 7.68 0.74
Bardosh x Sayhun 58.56 ± 1.05 18.04 0.65 49.32 ± 0.47 9.52 0.88
Sayhun x Bardosh 57.41 ± 1.00 17.44 0.54 48.22 ± 0.41 8.62 0.82
By the height of the main stem, F2 hybrids showed high degree of segregation in all combinations. The percentage of the variation ranged from 8.01 to 13.39%. The highest variation was observed in the hybrid combination of the reciprocal hybrid "Bardos x Sayhun" - 12.47 and 13.39%, respectively. While assessing 100 plants among them observed examples with main stem height from 60 cm to 110 cm. In this case, the transgression was both left-sided and right-sided. When hybrids were divided into 8 classes, deviation in 5 of them consisted between 15-20%, and in three classes - less than 10%.
All varieties in our experiments, although they were short type, differed with each other by in their heights. It can be seen from the table that all parents had average height - from 74 cm in the "Saykhun" variety to 85 cm in the "Kayraktash" variety, the variation in all varieties were no more than 4-5%. Segregation according to this characteristic in the second generation shows increasing of the variation by two times, and in the combination of "Bardosh x Sayhun" by three times. Hy-bridological analysis shows that almost in all combinations have classes with stem height above 90 cm, that presents great interest with its tolerance to lodging, plants increase growth and give additional biomass, which is very important for livestock. Selection in the following generations will give the opportunity to create such varieties.
Another quantitative trait of wheat, widely used in the breeding process as a marker for selection is the length and density of the spike. In our hybridological studies, analyzed inheritance of the trait of spike length in the varieties under study.
In the varieties "Saykhun", "Kroshka" and "Tanya" the average length of the spike is 8.87, 9.20 and 9.58 cm, respectively, and in the varieties "Bardosh" and "Kayraktash" is - 10.17 and 11.48 cm. It can be seen from the table that all parental forms are different by this trait. The longest spike has in the landrace "Kayraktash", relatively short form - in the variety "Saykhun", although in terms of the spike density, all the landraces are inferior than new commercial varieties, as one of the directions of breeding for yield was increasing of the spike density.
It was revealed that in all combinations, where variety "Kayraktash" was involved as one of the parents, spike length was average between the parameters of two parents and ranged from 10.66 to 11.19 cm. Only in one combination, where paternal form was variety "Tanya", the average spike length was longer than that of the parental forms. In the reciprocal hybrid combination "Bardosh x Saykhun", in both combinations spikes were longer than in both parents. Hence it can be concluded that the trait of the spike length in all combinations inherits dominantly.
In all parental forms, spike length was polymorphic, and the most polymorphic was in the variety "Kayraktash", where, despite the fact that the mean value was 11.48 ± 0.18, in 40% of
the studied plants spike length varied between 12.0 and 12. 9 cm, and in 70% of plants of the variety "Saykhun" it was within 9.0-9.9 cm. In all hybrid combinations of the second generation, was observed segregation with both left-sided and right-sided transgression. In three hybrid combinations, where one of the parents was landrace "Kayraktash", spikes with the length of more than 13 cm were found about 10% of the plants.
The average values for all parental forms belonged to the fourth class, where grain number was from 52.5 to 59.9. By this trait also revealed dominant inheritance and wide variability in the second generation. It can be seen from( fig. 4) that in all hybrid combinations the frequency of the occurrence (grain number 60.0-67.9) concerned to the fifth class or was larger than in both parental forms.
The grain number in a spike and the weight of the grain in a spike are the main trait of the yield of wheat crop. The distribution of classes in the second generation corresponds to the normal distribution. There are also classes that exceed the parent forms according to the traits studied, which makes it possible to select in the following generations in order to increase the yield without increasing the density of standing (the number of plants per unit area).
1000 kernel weight is one of the main quantitative traits that characterizes the productivity of the variety, its seed and technological qualities. Seeds with high 1000 kernel contain more nutrients, which contributes to rapid germination. This trait in the parental forms varied from 45.4 to 48.8 g. In the land-race "Kayraktash" it was 45.4 g. Basically, all the parental forms selected by us formed large grains weighing more than 45 g.
The grain size is little affected by environmental conditions and is in fact one of the most accessible structural traits for individual selection in early generations. Also, the 1000 kernel weight is characterized by high values of the heritability coefficient and is controlled in most cases by the domination type and overdomination, therefore this trait presents in the productivity breeding [7].
In our experiments, it was revealed that the share of ge-notypic variability in many combinations was high and varied from 0.70 to 0.88, and only in two combinations, this index was 0.55. In these combinations, 1000 kernel weight was less than that of both parental forms, the transgression was mainly left-sided. In reciprocal hybrids of "Bardosh x Saykhun" grain size was at the level of the best parent and more, the coefficient of the heritability h2 = 0.88 (table 1). These hybrid combinations present interest in the breeding aspect, since gives possibility of selection of transgressiv forms that exceed the original parent varieties according to the quantitative traits that determine the yield.
Conclusions: Thus, in the second generation, segregation of the quantitative traits was observed in all combina-
tions, and in all combinations where used landrace, the mean of tolerance to lodging, and, at the same time, produce an
values exceeded those of the parental forms and the share of additional biomass, which is very important for livestock
genotypic variability was high. This shows that using of the feeding.
landraces and geographically distant forms in hybridization Using landrace of wheat and accessions in crosses with
to create new varieties is more useful. commercial varieties increases the share of genotypic variabil-
In the hybridization of the geographically distant forms, ity in quantitative traits that gives possible selecting of the
all combinations have classes with stem height above 90 cm, transgressiv forms exceeding the original parent varieties by
which presents interest because plants preserve capability quantitative traits which determine the yield.
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