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Shodiyeva Ozoda Majidovna, Navai state pedagogical institute, senior teacher E-mail: [email protected]
INTRAPOPULATION VARIABILITY OF COTTON CULTIVARS
Abstract. Cotton, being facultative self-pollinator, in each generation can reproduce the modified plants. In researches it is revealed, that in population of cultivars on the studied traits gradually increased variability on years observed. It affects change of intrapopulation variability which leads to cultivar deterioration of economic traits of the given cultivar.
Keywords: Cotton, cultivar, variability definition, population, the adaptation, weight of a raw, cultivar deterioration, breeding.
In the course of growth and development a number of the mechanisms providing the adaptation of an organism to environment are created. According to many scientists, everyones change phenotypical homogeneous and high-quality cleanliness lead to change at cellular level, to infringement population homeostasis, i. e. a constancy of the internal environment of a genotype [2, 432].
As a whole high-quality population of plants is character-isedby the inheritance fixed variability on a complex of signs. Inherently, cotton cultivars is facultativelyrecrosspollinated, partially heterogeneous populations which keeping characteristic high-quality morphology, have the latent hereditary and paratypical variability which is shown in separate atypical years.
The durability of a cultivar, its long preservation in manufacture, and also adaptive properties and stability to illnesses depend on structure population. Cotton cultivars should be not only productive, have a positive complex of economic-valuable signs, but also should be homogeneous enough, keep valuable properties of cultivar in the course of reproduction. In preliminary reproduction new cultivars of cotton are finished on high-quality cleanliness with preservation of initial economic-valuable qualities. However, many new cultivars after their transfer in State test enoughquickly removed from reproduction, as their economic-valuable properties worsen and occurs "scattering" of morphological signs. As a rule, it occurs because of not finished new cultivars, their raised heterozygosis and finally, splitting and gradual accumulation of the separate genotypes different from initial population [5, 18; 6, 11].
Usually high-quality cleanliness of a selection line in the course of breeding-seed-growing completion is defined eyes - on morphological signs. In this case, the selection line homogeneous to approved signs can be actually non-uniform to economic-valuable signs.
Loss by a non-uniform cultivar ofits valuable initial qualities can be aggravated with wrong selection, at the same time because of presence of negative genetic correlations unilateral selection inevitably leads to strengthening variety of population biotypes.
Also more reliable revealing of the best genotypes in initial hybrid population or a selection line is actual that substantially causes its further selection perspectivity in process creation of a new cultivar.
Meaning that population of cultivars consists from ge-notypic variousplants, possibility of increase of variability in population of cultivars is very high. It is possible to lean on some factors to keep uniformity and positivity of economic significant signs. For example, correct zone placing of cultivars of cotton - to grow up those places where they are adapted and gives a high-quality stable crop, strict control of works of elite economy, application of optimum ways of care by crops and agroprocessing methods. In the course of adaptation to new condition of cultivar change a little. Variability such can lower genetic efficiency and a homeostasis of population and there is a deviation of a cultivar from the original descriptions.
Cotton, being a facultative self-pollinator, in each generation can reproduce the hybrids, supervised by active genes. Under D.J. Byubeykera's statement, "environment serves as a trigger for action of many genes" [3, 167].
Decrease in degree of uniformity of cultivars sometimes occurs and in elite farms. In a stage of primary reproduction and manufacture of elite seeds of cultivars of cotton always and continuously - before removal of this cultivar from manufacture, proceeds selections on a complex of signs. The individuals having an identical phenotype, but developing in various agroecological conditions of year and an area appear various in ontogenesis.
We have conducted researches by definition of degree of variability of some economic signs in population of some cultivars which are sowed different growing regions of our Republic. As object of researches cultivars of Omad, Akkurgan-2, Bukhara 6 and Bukhara 102 concerning kind G.hirsutum L. served. Each cultivar sowed in four allotments, till 20-25 plants. Analyses spent on the boxes collected from each cultivar on 80-100 pieces. In posterity of cultivars studied a variability range to some economic signs without breeding. The
Section 1. Biology
studied cultivars had typical morphobiological phenotype, however judging by changes in growth and development in cultivars were shown hidden genotypic distinctions which were observed in the form of different individuals.
Studying of any line or cultivar which is, as a matter of fact, population, always begins with it phenetics, i.e. characteristics phenotipicalfeatures of individuals (genotypes) entering into it, their distribution in population, an establishment of param-etersphenotypic variability to quantitative signs. The decision of these questions inevitably should lead to genetic research of population as such approach gives the chance to establish genetic structure of population, to reveal parities between the separate components characterizing population and further to pass to studying of action of factors defining its variability.
The weight of a raw of one box is more stable sign. The weight of raw of one box is an important structural component of productivity - the more largely a box, will be also an efficiency of plants more. For this sign polygene control, low factor genotypical, phenotipical and paratypical variability is characteristic. In our experiences the average index on plants of one cultivar is defined.
Three-year supervision in control group (without breeding), have shown, that weight of raw of one box slightly differ on years. In particular, in the first year at cultivar ofOmad weight of raw of one box varied within 5.6-6.6 g (an average 6.0). Degree of variability of sign was made by 4.2%. By next year these indicators made 5.4-6.5 g, 6.0 g and 5.4% accordingly. From this it is visible, that, by second year of sowing in region in cultivar population on another it was shown variability degree - though homeostasis change was to lesser degree observed. By third year limit indicators equaled 5.5-6.5 g, and, thus amplitude of variability made 5.5%, and average indicator weight of raw of one box of 5.9. It is visible, that, absolute value has not changed almost rather by first year (difference-0.10). But, raised degree of variability and it is possible to explaine on sharp divergence of limit values on the smaller and the greatest. Increase of degree of variability of sign in cultivar population despite not changes of absolute values was observed.
In population of cultivar of Akkurgan 2 the same was marked position. But in this case change of indicators since
the first year of supervision occurred more strongly than a cultivar of Omad. By third year it was marked high variability on 2.6% - rather by first year.
Above noted position shows that on grade population at which it is not conducted selections, in population degree популяционного a homeostasis gradually changes (decreases).
The cultivar Bukhara 6 has largely box. In our experiences the крупность boxes of plants of cultivarследущем to values: in the first year 6.3 g, by second year 6.1 g and by third year of 6.2. Variability degree equaled on 2.7, 2.3 and 3.1% accordingly. Variability degree on initial and next years differ on 0.4%. At cultivar Bukhara 102 though there is variability, but sharp distinction on years was not observed. And it shows most stability of cultivar on population level.
The important role in formation of structure of population belongs to selection process. There is an indisputable dependence between results of selection on a phenotype and size of heritability of sign. Selection of the best on phenotypes and high heritability gives to signs of genotypes shift of its values at posterity. Therefore, studying of change of indicator of heritability in the course of selection and possibility of the forecast of efficiency of selection to quantitative signs is of great importance for planning of selection process.
From references it is known that the most important component of productivity is the number of boxes on one plant. Hence, the increase in quantity of boxes at plant promotes productivityincrease. So, by many scientists it is proved, what not крупность boxes, and their quantity defines the general productivityof plants [1, 54; 5, 6-8; 4, 110].
Among the studied cultivars the most productivity in comparison with others had appeared cultivars of series Bukhara. Degree of variability of sign at cultivar Bukhara 6 on initial and next years differ on 0.8%. At cultivar Bukhara 102 the variability it is equal on 1.0%. And once again stability of cultivar proves to be true most. At cultivar of Omad a difference of variability of 2.6%, and at cultivar ofAkkurgan-2 variability has raised on 2.1%. Practically these indicators of variability it is not felt. But in population level it to lead to serious changes of homeostasis of cultivar. Вообщем productivity change on years accordingly to changes at the previous sign.
Table 1. - Variability of weight of raw of one box
№ Cultivars n 2009 y. 2010 y. 2012 y.
X ± Sx Lim. V% X ± Sx Lim V% X ± Sx Lim. V%
1. Омад 40 6.0 ± 0.04 5.6-6.6 4.2 6.0 ± 0.4 5.4-6.5 5.4 5.9 ± 0.3 5.5-6.5 5.5
2. Akkurgan 2 40 5.2 ± 0.08 4.9-5.7 6.1 5.0 ± 0.7 4.7-5.6 8.2 5.0 ± 0.2 4.6-5.6 8.7
3. Bukhara-6 40 6.3 ± 0.03 6.0-6.5 2.7 6.1 ± 0.1 5.9-6.3 2.3 6.2 ± 0.3 6.0-6.3 3.1
4. Bukhara 102 40 5.9 ± 0.02 5.6-6.2 3.2 5.9 ± 0.2 5.6-6.2 3.3 5.8 ± 0.5 5.6-6.0 3.0
Variability degree of cultivars studied in our experiences of the most northern part of republic was observed and we
was miscellaneous. And it depended from places of creation studied on other zone. It affects change intrapopulation
and primary test of the given cultivars. Gradual change of variability which lead to gradual deterioration of economic
homeostasis of cultivars which are created on an agroclimate indicators of the given cultivars.
References:
1. Avtonomov V. A. Genetic bases of selection for disease-resistant cultivars of cotton with the raised exit and quality of fibre: Diss. DSc.-Tashkent: 1993.- 54 p.
2. Altukhov J. U. P. Genetic processes in populations.- M.: Akademkniga, 2003.- 432 p.
3. Bjubejker D.J. A. Agricultural genetics.- M.: Kolos, 1966.- 167 p.
4. Kahharov I. T. Correlation of sign of precocity with some economic-valuable indicators of upland cotton // Evolutionary and selection aspects of precocity and adaptability of cotton and other agricultural crops // The international conference -Tashkent, 2005.- 110 p.
5. Sadykov S. S., Babayev D. M. Variability morphobiological traits of cotton depending on agroecological conditions // The Uzbek biological journal.- Tashkent, 1971.- P. 1-18.
6. Sodikov S. S. Population // The Uzbek Soviet encyclopedia.- Tashkent: Fan, 1977.- No. 9.- 11 p.
