Stability analysis of the new cotton lines

The genotype × environment interaction and the stability of eight cotton lines and the standard variety were studied during 2014-2017. The years of the study appeared to be as different ecological environments. The stability variances (2i and S2i) of Shukla (1972) and YSi index of Kang (1993) were calculated. It was found that the cotton genotypes tested interacted significantly with the environmental (year) conditions in terms of seed cotton yields, boll weigt, fiber length and lint persentage. For an effective selection of these traits, the genotypes had to be tested in different years at diverse environmental conditions and a calculation of the phenotypic stability parameters was necessary for a more precise selection. Based on Sukla’s variance stability parameters the breeding usefull stability was observed for all studed traits. Some lines were stable for more than one traits. Line 553 was found to be stable for the seed cotton yield, boll weight and lint percentage, lines 489 and 457 – for the boll weight and fiber length. These lines appeared to be very suitable for inclusion in crosses. According to Kang’s YSi index the complex breeding value (the average level of trait and stability) was found in: line 553 for the seed coton yield, boll weight, fiber length and lint percentage; line 489 for the boll weight, fiber length and lint percentage; line 535 for the seed coton yield and boll weight; line 449 for the boll weight and fiber length; line 457 for the fiber length. These lines are very suitable for the cotton breeding programs to create genotypes with a high expression and high stability of the traits.

Breeding assessment of new promising cotton lines

Cotton breeding in Bulgaria is mainly aimed at improving the earliness, productivity and fiber quality of modern varieties. The creation of new genetic diversity is one of the basic prerequisites for the success of breeding programs. The aim of the study was to evaluate cotton lines obtained by intraspecific and remote hybridization combined with backcross technology, with a view to their most effective usage in selection. Twenty-three lines were included in competitive variety trials conducted during the 2014-2017 period. The averaged results showed that lines 550, 639, 641, obtained by remote hybridization, appeared to be very promising. These three lines were distinguished by the best combination of productivity, fiber length and fiber lint percentage, and by these three indicators they exceeded the standard variety Chirpan-539. A new cotton variety Aida (No. 457) was approved, which in seed cotton yield and fiber yield, and technological fiber properties surpassed the standard varieties Chirpan-539 for earliness and productivity and Avangard-264 for fiber quality. The candidate variety 535 continued the state variety testing. Two new candidate cotton varieties No. 550 and No. 553 were released. In the state variety testing the three candidate varieties confirmed their qualities. The obtained lines, distinguished by one trait or by a complex of qualities, enriched the gene pool of Bulgarian cotton.

Response of Cotton to Conservation Tillage Plus Wheat Straw Management and Nitrogen in Wheat Based Cropping System

Zero tillage straw retained with optimum N is an important strategy to increase soil fertility and cotton (Gossypium hirsutum L.) yield in wheat (Triticum aestivum L.)-cotton system. A 3 years field experiment was conducted during 2014, 2015 and 2016 to study the impact of two tillage techniques [zero tillage plus wheat straw retained- ZTsr and conventional tillage-CT straw burnt (CTsb, with disc plow, tiller, rotavator, and leveling operations)] and four nitrogen rates namely 0, 100, 150 and 200 kg N ha-1 on cotton yield and soil fertility. Results indicated that bolls/plant–1, weight per boll, seed cotton yields, lint percentage and N recovery efficiency were highest with 150 kg N ha–1. Interaction tillage into N indicated that ZTsr had graeter bolls plant-1, bolls weight, seed cotton yields, lint percentage and N recovery efficiency compared to CTsb. ZTsr had more soil organic matter (SOM) and total soil nitrogen (TSN) compared to CTsb. ZTsr with 150 kg nitrogen per hectare enhanced cotton yield and soil fertility on sustainable basis in arid environment of Dera Ismail Khan.

Genome-wide Association Study Reveals Novel Quantitative Trait Loci and Candidate Genes of Lint Percentage in Upland Cotton Based on the CottonSNP80K Array

Cotton (Gossypium spp.) is an important natural textile fiber and oilseed crop widely cultivated in the world. Lint percentage (LP, %) is one of the important yield factor, thus increasing lint percentage is a core goal of cotton breeding improvement. However, the underlying genetic and molecular mechanisms that control lint percentage in upland cotton remain largely unknown. Here, we performed a Genome-wide association study (GWAS) for LP based on phenotypic tests of 254 upland cotton accessions in four environments and BLUPs using the high-density CottonSNP80K array. A total of 41,413 high-quality single-nucleotide polymorphisms (SNPs) were screened and 34 SNPs within 22 QTLs were identified as significantly associated with lint percentage trait in different environments. In total, 175 candidate genes were identified from two major genomic loci (GR1 and GR2) of upland cotton and 50 hub genes were identified through GO enrichment and WGCNA analysis. Furthermore, two candidate/causal genes, Gh_D01G0162 and Gh_D07G0463, which pleiotropically increased lint percentage were identified and further verified its function through LD blocks, haplotypes and qRT-PCR analysis. Co-expression network analysis showed that the candidate/causal and hub gene, Gh_D07G0463, was significantly related to another candidate gene, Gh_D01G0162, and the simultaneous pyramid of the two genes lays the foundation for a more efficient increase in cotton production. Our study provides crucial insights into the genetic and molecular mechanisms underlying variations of yield traits and serves as an important foundation for lint percentage improvement via marker-assisted breeding.

Study on Population Changes of Important Sucking – Pests (Aphis Gossypii (Glov.) and Bemisia Tabaci (G.) in the New Varieties Second Plant (After Canola) in the Golestan Province of Iran.

Investigating the population dynamic of important cotton pests on new cotton varieties is important. Cotton cultivars have important pests such as thrips, aphids, whitefly and bollworm. Considering the premature cultivars with proper yield for second cultivation in cotton-growing Golestan province at the north of Iran, this study seems necessary. This genotypes was cultivated with 9 treatments in 4 replicates. A completely randomized block design was carried out in Hashem Abad research station in a spray-free plot with the dimensions of 30 × 80 cm in 2018-2019 years. According to the results of this study, analysis of variance of two years showed that the yield of N2G80 with 1538 g in the plot with 41.7% lint percentage had the highest yield, and M13 with 685 g in the plot and 35.8% lint percentage in the lowest yield they had.The infestation rate of the genotypes tested in the population of green aphid of cotton in K880-2 and Golestan® cultivars was 48.88 and 40.31 in aphid with the highest density, and the SKT-133 and TBL-60 genotype respectively with 27.15 and 29.11 aphids per leaf had the least infestation. The amount of infestation of the genotypes tested to the population of whitefly cotton on the N2G80 and TBL-60 genotype was 90.76 and 68.86 whitefly in the leaf with the highest infestation and N2G80 and TBL-60 genotype respectively with 40.05 and 75.51 white fly in leaf were the least infested. Correlation coefficient between traits was equal to 0.55. The number of bolls per plant was not correlated with other traits including boll weight, lint percentage, aphid and white fly.