CC BY
0CREATION OF A NEW COTTON VARIETY (G.hirsunum L.) BY
LINE-BASED CULTIVATION
Khasanov R.K.
Associate Professor of the Department of Agrobiology and Cultivation of Medicinal Plants of the Technological Faculty of Tashkent Branch of Samarkand State University of Veterinary Medicine, Animal Husbandry and Biotechnology https://doi.org/10.5281/zenodo.14029023
Abstract. Salt resistance of plants is an urgent problem of crop production, attracting the attention of many researchers and practitioners of the agro-industrial complex in connection with the need to increase yields on saline soils and the development of saline lands. Laboratory studies have shown that the L-246 line was cleared of atypical plants in order to stabilize morphological and economic characteristics in the population. As a result of cultivation work on the basis of the L-246 line, was created a new variety of cotton Gulshan.
Keywords: line, cultivation, salt, variety, introgressive, synthetic, salty, soil, yield, trait, adaptation, ruderal.
Introduction.
Today, cotton is one of the main technical crops in agriculture worldwide, primarily cultivated for its fiber. According to the U.S. Department of Agriculture, countries like China, Pakistan, and India have achieved significant developmental progress largely due to cotton fiber production and processing. Improving cotton varieties genetically requires involving wild diploid species, ruderal forms, and synthetic introgressive forms in practical cultivation processes. In this regard, creating initial sources and new varieties of cotton that are genetically resistant to various diseases and pests by utilizing wild ancestors is one of the pressing issues.
The role of this approach is significant in the evolution of genera and species among many cultivated plants. Additionally, it opens up opportunities in cultivation to integrate different traits and characteristics of plants belonging to various species and genera into new varieties. Research shows that intraspecific hybridization has limitations in solving many cultivation problems.
Currently, there are over 200,000 species of angiosperms on Earth, of which 250 species, or 0.12%, are cultivated and utilized by humans. Many traits not present in cultivated species are found in wild types.
Research:
The study involved the synthetic introgressive L-280 line developed with wild diploid species G. anomalum and G. stocksii, the medium-fiber variety C-4534, and the L-246 line created from the hybrid combination of (G. anomalum x G. stocksii) x C-4534. The resulting "Gulshan" variety was developed based on this line, using Namangan-77 and AN-Boyavut-2 varieties as standards.
Methods:
The research employed various cultivation methods, including hybridization and polyploidy, along with comparative morphology, phenological observations in both laboratory and field conditions, fiber quality assessment using an HVI apparatus, and statistical analysis with field and lysimetric experiments (2007).
Results:
Due to the necessity of enhancing crop yields and utilizing saline soils, as well as addressing salt tolerance, this study has garnered the attention of numerous agro-industrial researchers and practitioners, identifying salt resistance in crops as a critical issue. Crop yield in saline conditions is influenced by multiple factors, primarily the plant's nature, the quantity and quality of salts in the soil, and the effectiveness of agrotechnical measures. Combatting soil salinization is conducted both through the application of reclamation practices and the use of specialized agricultural techniques and biological methods, aiming to develop salt-resistant varieties.
Creating Salt-Tolerant Varieties
Developing salt-tolerant varieties requires understanding the heritability of this trait, the number of genes involved in salt tolerance, and the expression of these genes across various genotypes. To establish a methodology for creating salt-tolerant varieties, it is essential to study comprehensively the inheritance of salt tolerance, the genetic basis of this trait, and its correlation with other economically valuable, physiological, and quality characteristics.
In recent years, global research has increasingly emphasized using wild species in scientific studies aimed at improving the agronomic and quality characteristics of medium-fiber cotton. Notably, rare amphidiploid and hexaploid forms derived from wild species, such as G. longicalyx Hutch et Lee., G. barbosanum Phill., G. triphyllum (Harv. et al.) Hochr., G. armourianum Kearney, G. gossypioides (Ulbr.) Standley, G. anomalum, G. stocksii Mast., G. laxum (Rose and Standley), and others, have led to the creation of introgressive recombinant forms. Extensive research is underway to determine the genetic-cultivation principles in these introgressive forms, such as heritability, variability, and correlational relationships of morpho-economic traits. Consequently, identifying the genetic potential for yield, early maturity, fiber quality, and efficiency in medium-fiber cotton, along with creating new lines and varieties through the extensive use of wild species with various genomes, remains a key objective.
The study involved the L-280 line, obtained from hybridization and subsequent selection of wild species G. anomalum and G. stocksii, as well as the L-246 line developed from complex interspecies hybridization [(G. hirsutum (C-4880) x G. stocksii) x G. hirsutum (C-4534)]. These were compared with the medium-fiber variety C-4534, with Namangan-77 and AN-Boyavut-2 varieties serving as controls.
The L-246 line has a height of 100-110 cm with a compact, cylindrical stem. The stem is sturdy, does not lodge, and is slightly hairy and green. The fruiting branches belong to branching type 1-1.5, with the first fruiting branch located at nodes 6-7. The leaves are of medium size, dark green, three- to five-lobed, and the bolls are of medium size and open well.
The research was conducted at Durmon experimental base and Zangiota experimental stations in Tashkent region, under the "Biology and Technology of Technical Crop Seeds and Fibers" laboratory of the Genetics and Plant Experimental Biology Institute of the Academy of Sciences of the Republic of Uzbekistan.
In the study, each variety and F1 hybrid combination was arranged with a randomized method in three replicates, with four rows of 25 plants per row. The planting scheme was 60x25x1. During the experiment, the inheritance and variability of important morpho-biological and valuable economic traits in F1 hybrids, as well as the variability range of specific economic traits in F2 hybrids, were analyzed and compared with the parent forms.
Standard cultivation methods were used in growing the plants. During the study, traits such as plant height, leaf water content, water retention ability, transpiration activity, and yield components were measured. Plant height was measured with a measuring tape, and the water content in the plant was determined by weighing the wet and dry biomass on an analytical balance. Water Retention Capacity №1^3) х100 Рз
where:
P1 = fresh mass of the leaf
P3 = mass of the leaf after drying for 20 minutes.
To determine the total water content and water retention capacity of the leaves, five leaves
were taken from each biotype. These leaves were weighed on an electronic scale and left at room
temperature. After a 2-hour exposure, their weight was measured again. The leaves were then dried
in an oven at 100-105°C for three days, and the dry weight of the leaves was recorded. This method
allowed for calculating the total water content and water retention properties of the leaves.
For statistical analysis, the method of B.A. Dospekhov was used. Transpiration activity
was measured following the method of L.A. Ivanov, while leaf water retention capacity was
determined using the method of A.A. Nichiporovich. 1200
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Physiological Indicators of Water Exchange in Optimal and Water-Deficit Conditions for
Gulshan Cotton Variety Studies have been conducted on the physiological indicators of water exchange in Gulshan cotton plants under optimal water regimes, water scarcity, and high-water levels using lysimeter conditions. One of the goals of the research was to develop cotton varieties and donor lines that exhibit resistance to both drought and soil salinity through the use of introgressive lines. Presently, one of the critical issues in cotton farming is not only introducing high-yielding varieties that meet global fiber quality standards but also recommending new cotton varieties that are resilient to adverse environmental factors. Enhancing cotton's adaptability to water-scarce conditions— through understanding the relationship between genotype and environmental factors in creating drought-tolerant varieties—is essential. This includes studying genetic and morpho-biological mechanisms and identifying donors resistant to adverse environmental conditions from existing lines and hybrid populations.
Research was conducted to assess the adaptation of introgressive lines and cotton varieties to different water availability conditions and varying soil salinity levels. Over several years, hybrid
forms of cotton derived from wild species have been studied, resulting in the selection of lines resistant to drought and soil salinity. Among these valuable lines is the L-246 line, selected from the cross C-4534 x L-280 through multiple selections under highly wilt-infected conditions. In this combination, the paternal L-280 line, derived from interspecific hybrids of the wild cotton species G. anomalum and G. stocksii, contributed valuable traits.
These studies support the creation of varieties with a high tolerance to drought and salinity, making them suitable candidates for use in challenging environments where water resources are limited.
The study began with a comparative analysis of the Gulshan cotton variety, developed through interspecies hybridization at the institute, against control varieties AN-Boyavut-2 and Namangan-77. The drought resistance of these varieties was monitored over three years. Results indicated that, under conditions of water scarcity, the Gulshan variety consistently demonstrated higher performance across all three years. Compared to the control varieties AN-Boyavut-2 and Namangan-77, the Gulshan variety achieved higher yields in each environment, with the highest optimal yield observed at a 0-2-1 ratio.
According to N. Sanaev (2019), under drought conditions, cotton plants develop deep taproots that enable the plant to grow taller and accumulate essential yield components. However, when plants receive excess water, their rapid growth can lead to a reduction in yield. Conversely, if the cotton root system does not penetrate deeply into the soil to access moisture, the plant remains shorter and tends to shed its yield components due to insufficient water uptake.
Table 1
yield data for samples under different water regimes at Durmon experimental site in Qibray
district, using a 60-25-1 planting scheme:
№ Types of species Water regime the weight of 1000 seeds, g the weight of cotton in one boll, g fiber length, mm fiber yield % yield, centners/hecta re
AN - 0-1-0 86,0±1,5 4,6±1,3 34,1±1,2 35,6±1,8 20,4 ±1,26
1 Boyovut - 0-2-1 110,1±1,0 5,2±0,5 33,6±0,6 35,4±0,9 35,6 ± 1,38
2 1-2-1 100,2±1,1 5,0±1,1 33,2±1,2 34,3±1,2 31,2 ± 1,31
0-1-0 93,2±1,1 5,6±1.1 35,0±1,1 38,6±1.1 26,6 ± 1,1
2 Gulshan 0-2-1 119,2±0,4 6,2±0,3 34,3±0,5 39,2±0.3 38,5 ± 1,0
1-2-1 110,2±1,2 6,0±0.9 34,6±0,9 39,3±1.1 34,4 ± 1,3
0-1-0 76,2±1,6 4,3±1.4 34,1±1,4 35,1±1.4 21,2 ± 1,8
3 Namangan 0-2-1 102,2±1,2 5,3±0.8 34,3±1,0 36,2±0.9 28,1 ± 1,5
-77 1-2-1 100,2±1,3 5,2±1.1 33,2±1,2 33,1±1,2 30,4 ± 1,6
The findings from our experiments confirmed that achieving high yields is optimal when irrigation is timed precisely with key growth phases: the onset of full flowering, fruit setting, and the beginning of boll opening. (Refer to Table 1).
When assessing each variety's tolerance to salinity, a coefficient of resistance is calculated. In laboratory conditions, this involves using a roll culture method on filter paper, where seedlings
are grown in a solution containing chemically pure NaCl salt at 0.7 MPa (9.8 g/L). Seedling length measurements in this salt solution provide insights into each variety's tolerance (see Table 2).
As shown in Table 2, the selected Gulshan variety exhibits greater seedling length in plain water compared to the control, indicating superior growth potential in non-saline conditions. In saline environments, however, it demonstrates performance close to other varieties, underscoring its resilience under both optimal and challenging conditions.
Table 2
the salt tolerance coefficients of the Gulshan cotton variety compared to control varieties:
№ Types 5 days 0 Resilience coefficient
H2O 1,5% (NaCl)
1 AN- Boyovut--2 13,65 ± 0,48 3,35 ± 0,42 0,24 ± 0,42
2 Gulshan 15,44 ± 0,56 5,56 ± 0,48 0,36 ± 0,48
3 Namangan 77 14,24 ± 0,21 4,87 ± 0,32 0,34 ± 0,32
The resistance coefficient for the Gulshan variety showed the highest values among the tested samples. This suggests that introducing this variety into moderately saline soils would yield positive results.
Conclusion
Beyond the scientific and practical significance of intervarietal and distant hybridization studies, understanding the taxonomy, genetics, cytoembryology, and phylogenetic issues related to the Gossypium genus is crucial. Currently, there is a lack of comparative data on the donor capacity of hybrids obtained from one-gene and multi-gene species of cotton. The study of distant hybridization holds substantial theoretical and practical importance. The findings from this research can facilitate better selection of parent species to obtain high-yielding hybrids, thereby enhancing cotton cultivation in varying environmental conditions.
REFERENCES
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