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On the basis of established high indicators for the most economically valuable traits, specialized trait collections have been created as starting material for the various selection directions in cotton: specialized collection for high productivity; specialized collection for fiber length improvement and other quality indicators; specialized collection for higher lint percentage. Organization of the relevant collections was in accordance with the requirements of selection process for a complex evaluation as biological and economic qualities, adaptability to the specific conditions and others. With these, commercial geneplasm will be preserved, the varietal structure and the hereditary basis of Bulgarian selection will be enriched and expanded. Created specialized trait collections will facilitate the use of available genetic resources in the various directions of cotton breeding and are the basis for creating new cotton varieties with higher productivity and improved fiber quality. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the productive potential and evaluate the fiber properties of the new Selena cotton variety. The variety was studied in competition variety trials conducted in 2017-2022 in the experimental field of the Field Crops Institute in the town of Chirpan. In the IASAS system the variety was tested in 2021-2022. It was approved as a new cotton variety in 2023. Selena variety was created by remote hybridization from the crossing of the allotetraploid Gossypium thurberi Tod. × Gossypium raimondii Ulbr. with Dorina variety and subsequent backcrossing with Darmi variety. Selena variety is an early and productive new cotton variety with improved fiber quality. The vegetation period was 106-111 days. In seed cotton yield of 1663 kg/ha, on average for 6 years, it surpassed the standard cultivar Chirpan-539 by 12.3%. According to the IASAS data, in seed cotton yield of 2163 kg/ha it exceeded the two standard cultivars, Chirpan-539 - by 2.2%, Avangard-264 - by 1.3%, the average standard (average of the two standards) - by 1.8%. In lint yield of 95.5 kg/ha Selena variety was equal to Avangard-264, surpassed Chirpan-539 by 2.9% and respectively the average standard - by 1.4%. Selena variety had a number of valuable technological fiber qualities and in some indicators surpassed both standard cultivars. Compared to the two standard cultivars it had better Spinning Consistency Index (SCI), greater Upper Half Mean Length and fiber strength, lower micronaire, better spectroscopy with RD difference reflection than Chirpan-539, less yellowness than Avangard-264 and better fiber whiteness. Selena variety combines better productivity with better technological fiber qualities than the standard cultivars, which defines it as a new achievement in the selection of cotton in our country. [ABSTRACT FROM AUTHOR]

Heterosis is a method of increasing productivity and is used in many crops. In cotton, heterosis is mainly related to yield and fiber length. Two male-sterile cotton lines ms 273 and ms 274 were included in crosses with five modern varieties: Chirpan-539, Natalia, Rumi, Helius and Nelina. Heterosis manifestations were found for productivity/plant (7.4-63.8%) and fiber length in the F1 hybrids. The cultivar Chirpan-539 and Rumi variety, with high GCA for fiber length and high variances of SCA, emerged as suitable for heterosis selection of this trait. The crosses 273 × Nelina and 274 × Nelina, with the highest productivity\plant (39.5-42.1 g) and the highest heterosis (61.9-63.8%), the second one with high SCA effects, are of interest for the heterosis selection of productivity. The crosses 274 × Chirpan-539 and 274 × Natalia, with the longest fibers (28.9-29.3 mm) and heterosis (2.1-3.5%), the first one manifested high SCA effects, are of interest for the heterosis selection of fiber length. The results obtained are encouraging for the development of heterotic selection and practical use of heterosis in cotton based on male sterility. [ABSTRACT FROM AUTHOR]

The inheritance of most important economic characters, heterosis and combining ability were studied in six interspecific (G. hirsutum L. × G. barbadnese L.) and three intraspecific hybrid combinations. There were found different types of inheritance of productivity, boll weight and lint percentage and fiber length in the individual crosses. The genetic variance for productivity and fiber length was mainly non-additive, while for lint percentage it was additive. Although non-additive genetic variance prevailed for productivity and fiber length, only individual crosses showed positive heterosis, outperforming the better parent. Of the female forms, the cultivar Helius was identified as a very good general combiner for productivity. From the male forms the cultivar Ashkabat emerged as a very good general combiner for productivity, boll weight and lint percentage. The cultivars Mytra (female), Karshinski-2 and C-6037 (male) were determined as very good general combiners for fiber length. All these cultivars, with the exception of C-6037, had low SCA variances, their high GCA was mainly due to additive gene effects, and they were very suitable for synthetic selection. The cross Helius × Ashkabat was found to be most valuable for the selection of productivity because of the highest mean performance and the highest level of heterosis with high SCA effects. All intraspecific hybrids were found to be most promising for improving lint percentage. The interspecific cross combinations Mytra × C-6037, Helius × C-6037 and Mytra × Karshinski-2, having the longest fibers, the first two with high SCA effects were most valuable for fiber length improvement. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the productive potential and to evaluate the fiber technological properties of the new cotton varieties Tiara and Melani, compared to the standard cultivars. These varieties were studied in competitive varietal trials conducted in 2017-2019, in the experimental field of the Field Crops Institute in Chirpan. In the IASAS system, the Tiara and Melani varieties were tested in 2019-2020. They were approved as new varieties in 2021. Both varieties were obtained by remote hybridization and belong to the Gossypium hirsutum L. species. Tiara and Melani are early and productive varieties, in terms of seed cotton yield, on average for three years, they surpassed the cultivar Chirpan-539 (standard for productivity) by 8.1% and 6.5%, respectively. According to IASAS data, in seed cotton yield, 2809 kg/ha for Tiara and 2784 kg/ha for Melani, on average for two years, they equalized with the cultivar Chirpan-539 and outperformed the cultivar Avangard-264. In terms of fiber yield (1141 kg/ha and 1066 kg/ha) Tiara variety exceeded the two standard cultivars, Melani variety surpassed the cultivar Avangard-264 and leveled with the cultivar Chirpan-539. These varieties had a number of valuable fiber technological qualities and in some respects exceeded the two standard cultivars or equalized with the Avangard-264. The Tiara variety showed better agronomic performance than the Melani variety, achieving higher fiber yield, as a result of higher lint percentage. The Melani variety had better fiber technological qualities than the Tiara variety. Compared to the standard cultivars, the Melani variety was characterized by a better spinning, consistency index (SCI), lower micronaire, greater strength and better spectroscopy with reflection of the difference RD. This variety showed a better combination of the agronomic indicators with the fiber technological qualities than the Avangard-264, a standard for fiber quality. The results obtained define the new cotton varieties as a very good combination of earliness, productivity and fiber quality. This makes them very valuable for the cotton production and breeding programs with cotton. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the productive potential and to evaluate the technological fiber properties of the new cotton variety Anabel, compared to the standard varieties. The new variety was studied in competitive varietal trials conducted in 2014-2017 in the experimental field of the Field Crops Institute in Chirpan. In the IASAS system, the Anabel variety was tested in 2017-2018. It was approved for the new cotton variety in 2021. Anabel variety was obtained by intraspecific hybridization and belongs to the species Gossypium hirsutum L. Anabel is an early and productive variety. According to IASAS, in seed cotton yield - 2026 kg/ha, on average for two years, it was inferior by 3.1% to the cultivar Chirpan-539 - standard for productivity and was equal to the cultivar Avangard-264 - standard for fiber quality. In terms of fiber yield, it was equal to Chirpan-539 and was superior to Avangard-264, as a result of the higher lint percentage. This new variety showed a number of valuable fiber technological qualities and in some respects exceeded both standard cultivars or was equal to Avangard-264. Compared to the standard cultivars, the variety Annabel had a better fiber spinning (SCI) Index, longer fiber, lower micriner, greater strength and better spectroscopy with reflection of the RD difference. The obtained results define the new variety Anabel as a very good combination of earliness, productivity and fiber quality. This makes it very valuable for cotton production and selection programs with cotton. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the productive potential and to evaluate the fiber quality characteristics of the new cotton Aida variety. The variety was studied in competitive variety trials conducted in 2014-2017 in the experimental field of the Field Crops Institute in town of Chirpan. In the system of the IASAS (Exclusive Agency for Variety Testing, Approbation and Seed Control) the Aida variety was tested in 2017-2018. It was approved as a new cotton variety in 2019 and was certified in 2020. It was obtained by remote hybridization and backcross technology. Aida variety showed high and stable productivity during the years of testing. According to the IASAS data, in the seed cotton yield of 2380 kg/ha, on average over two years, it exceeded the two standards - Chirpan-539 and Avangard-264, respectively by 11.3% and 14.7%, the average standard - by 13.0%. It outperformed the standards in September harvest and in fiber (lint) yield. The Aida variety was distinguished by its high fiber quality, and in some fiber properties it was superior to both standards or equalized with Avangard264 variety - standard for fiber quality. Compared to the standard varieties, the Aida variety had a better fiber consistency (SCI) Index, greater Upper Half Mean Length (UHML), better uniformity in fiber length and a better spectroscopy with a reflection of the RD difference. The content of short fibers was very low. The results obtained identified the Aida variety as a very good combination of earliness, productivity and fiber quality. This outlined it as a very valuable for the cotton production and for the cotton breeding programs. [ABSTRACT FROM AUTHOR]

Line × tester analysis of 5 Bulgarian cotton varieties used for mothers and 3 foreign ones as fathers was applied to study the inheritance of the most important economic traits and the breeding value of parental forms (G. hirsutum L.) and F1 hybrids. The trial was conducted in 2013-2014 by block method in three replicates. Different types of inheritance were observed by the productivity, boll weight and length and lint percentage of the fibre. Exhibition of heterosis was most pronounced by productivity reaching 39.1%. For all studied traits the genetic variance was mainly of non-additive type and the prognosis for selection in early segregate generations could not be good. The varieties of Bulgarian selection, Boyana and IPK Nelina had high GCA for productivity and fibre lint percentage. Their high GCA was combined with low SCA variances making them suitable for the synthetic selection. Of the foreign varieties, the Turkish Nazilli 954 had high GCA for the fibre lint percentage, the Greek Corina - for the fibre length. Because of the high SCA variances they appeared to be more suitable for the heterosis selection. [ABSTRACT FROM AUTHOR]

Тhe new brown cotton varieties Egea and Nike were achievements in a new direction in the Bulgarian cotton breeding. They belong to a new generation of varieties with naturally coloured fibre of high ecological and economic effects. The most valuable characteristic of the two new varieties was their longer fibre than that of Izabell variety approved as a standard for the coloured cotton. According to data of the Executive Agency for Variety Testing, Approbation and Seed Control, Egea variety in fiber length (modal 23.32 mm and staple 26.83 mm) surpassed the standard variety Izabell by 1.35 mm and 1.57 mm, and Nike variety was superior by 0.37 mm and 0.54 mm. As a result of the longer fiber they also are distinguished by better spinning characteristic. With these two varieties significant progress in improving the fiber quality of coloured cotton by selection has been made. By earliness, seed cotton yield, fiber lint percentage and lint yield, the varieties Egea and Nike were equal to Izabell variety or slightly superior to it. Concerning productivity they were close to the white cotton standards, seed cotton yields were only by 1.3-1.5% less than Chirpan-539 (standard for productivity), and by 0.6-0.9% than Avangard-264 (standard for fiber quality). They were inferior in fiber lint percentage and lint yield by 7.3 kg/da (8.9%) and 7.8 kg/da (9.6%) to Chirpan-539 and by 2.2% and 2.9% to Avangard-264. [ABSTRACT FROM AUTHOR]