Multivariate classification of cotton cultivars tolerant to salt stress

ABSTRACT Two multivariate methods were adopted to classify salt-tolerant cotton genotypes based on their growth and physiological traits. The genotypes were cultivated in a greenhouse and subjected to 45 days of irrigation with saline water from the V4 phase onwards. Irrigation was performed with saline water with electrical conductivity (ECw) of 6.0 dS m-1. A factorial-randomized block design was adopted with nine cultivars, two treatments of ECw (0.6 as the control, and 6.0 dS m-1), and four replicates. Plants were evaluated for growth, gas exchange, and photosynthesis. The data were statistically analyzed using univariate and multivariate methods. For the latter, non-hierarchical (principal component, PC) and hierarchical (UPGMA) models were used for the classification of cultivars. Significant differences were found between cultivars based on univariate analyses, and the traits that differed statistically were used for multivariate analyses. Four groups were identified with the same composition in both the PC and UPGMA methods. Among them, one contained the cultivars BRS Seridó, BRS 286, FMT 705, and BRS Rubi, which were tolerant to salt stress imposed on the plants. Photosynthesis, transpiration, and stomatal conductance data were the main contributors to the classification of cultivars using the principal component method.

Productivity of medium-fiber cotton genotypes selected according to test characteristics in combination with classical breeding methods

The most important factor in the intensification and rise of the production of the cotton industry in Tajikistan is the selection of new varieties characterized by high yield and its quality. The increase in the production of the cotton industry can be achieved not by expansion of acreage, since this possibility is very limited in a mountainous country, but by breeding new varieties of cotton and spreading them into production. The use of photosynthetic test characteristics in breeding contributes to the process of creating new varieties that meet the demand of agricultural production and the textile industry, i.e. varieties with a complex of economically useful features — precocity, high productivity, resistance to diseases and pests, optimal adaptive properties, characterized by high fiber yield and its technological quality. By methods of hybridization and selection by offspring on the basis of photosynthetic test characteristics from domestic and foreign variety samples, 28 introgressive genotypes were created that are characterized by complex of economically useful traits. It was found that out of the 28 genotypes of medium-fiber cotton studied by us, according to the main indicators of productivity — the number of full-fledged boxes per plant, the mass of raw cotton of one box and the yield — 6 genotypes were notable. The number of boxes per plant in the most productive was 12–15 pieces, the mass of raw cotton of one box is up to 6.6 g, and the yield of raw cotton is from 71.5 to 93.0 g/plant, which is significantly higher than in the standard Hisor variety.

Genotype plus genotype by-environment interaction biplot and genetic diversity analyses on multi-environment trials data of yield and technological traits of cotton cultivars

ABSTRACT: Understanding the genetic diversity and overcoming genotype-by-environment interaction issues is an essential step in breeding programs that aims to improve the performance of desirable traits. This study estimated genetic diversity and applied genotype + genotype-by-environment (GGE) biplot analyses in cotton genotypes. Twelve genotypes were evaluated for fiber yield, fiber length, fiber strength, and micronaire. Estimation of variance components and genetic parameters was made through restricted maximum likelihood and the prediction of genotypic values was made through best linear unbiased prediction. The modified Tocher and principal component analysis (PCA) methods, were used to quantify genetic diversity among genotypes. GGE biplot was performed to find the best genotypes regarding adaptability and stability. The Tocher technique and PCA allowed for the formation of clusters of similar genotypes based on a multivariate framework. The GGE biplot indicated that the genotypes IMACV 690 and IMA08 WS were highly adaptable and stable for the main traits in cotton. The cross between the genotype IMACV 690 and IMA08 WS is the most recommended to increase the performance of the main traits in cotton crops.

Breeding Practice Improves the Mycorrhizal Responsiveness of Cotton (Gossypium spp. L.)

Maximizing the function of indigenous arbuscular mycorrhizal (AM) fungi by choosing specific crop genotypes offers one of the few untapped opportunities to improve the sustainability of agriculture. In this study, the differences in mycorrhizal responsiveness (MR) in plant growth and shoot phosphorus (P) content among cotton (Gossypium spp. L.) genotypes from different release dates were compared and then the relationships between MR and P uptake-related traits were determined. The experimental design in a greenhouse included 24 genotypes released from 1950 to present in Xinjiang Province, inoculation with or without AM fungi, and P levels (15 and 150 mg P kg–1 added as KH2PO4). Results showed that the modern cotton genotypes exhibited a higher degree of mycorrhizal colonization, the hyphal length density (HLD), and mycorrhizae-induced changes in shoot growth than the old genotypes when inoculated with indigenous AM fungi at both the P levels. Moreover, MR was highly correlated with the HLD at low P levels and the HLD may provide useful insights for future cotton breeding aimed at delivering crop genotypes that can benefit more from AM fungi.

Water relations composition among Egyptian cotton genotypes under water deficit

Background: water shortage is one of the major factor effects on growth characters and yield of most crops. Objective: this study was conducted to get to know the reactions of some Egyptian cotton genotypes to water deficit. Methods: The genetic materials used in this study included thirteen cotton genotypes belonging to Gossypium barbadense L., from the Cotton Research Institute (CRI), which was devoted to establishing the experimental materials for this investigation. Results: the ratio of GCA/SCA was less than unity for all studied indices, indicating predominance of non-additive gene action (dominance and epistasis), which is an important in exploitation of heterosis through hybrid breeding. Results: The data showed significant reduction in water relationship characters for all parental genotypes under stress conditions. The Egyptian variety Giza 68 gave high values for most water relationship characters. Data revealed that the greater the value of tolerance index is, the larger the yield reduction is under water deficit conditions and the higher the stress sensitivity is becoming. The parental genotypes Giza 96 showed the highest reduction in yield under water deficit conditions. At the same time, the cross combination Minufy x Australy showed higher values of yield reduction followed by the combinations Giza 67 x Australy. Of the male parents, the Russian genotype 10229 recorded the best GCA values for most water relationship characters. At the same time, the female parents, the old Egyptian genotype Giza 67 recorded the best values and exhibited good general combined for most water relationship characters. The cross combinations Giza 86 x Pima S6, Giza 77 x Pima S6, Giza 94 x Dandra and Giza 96 x Australy showed significant desirable SCA effect for most characters. Conclusion: relative water content %, osmotic pressure, chlorophyll and carotenoids content indicates better availability of water in the cell, which increases the photosynthetic rate. Also, the higher level of proline accumulation in the leaves which was recorded under deficit water suggests that the production of proline is probably a common response of plant under water deficit conditions.

Molecular Dissection for Boll Shedding in Upland Cotton Using Microsatellites

DNA markers application in marker-assisted breeding of cotton is handicapped due to low genetic diversity in cotton germplasm. The present study was designed to identify DNA markers, predominately simple sequence repeats (SSRs), associated with tolerance/resistance to heat stress as a consequence of boll shedding. To find out the genetic diversity a total of 24 cotton genotypes and 50 SSR primers were used. Total 288 alleles were produced with an average of 5.7 alleles per primer. Bootstrap cluster analysis used to generate a dendrogram that cluster the 24 accessions into two main clusters. Eleven out of 24 genotypes fall in a single cluster. Phenotypically H-4074 gives more diversity, while genotypically H-4074 sheared the same genetic background as H-4070, H-4091 and H-4090. Low genetic diversity was observed among both genotypic and phenotypic as maximum varieties fall in single group. This study helps for selecting diverse accessions with multiple phenotypic traits, which were drought to boll shedding. It suggests further elaborating the molecular genetic diversity by using new SSR marker to improve the yield of cotton cultivars. These preliminary results set the stage for initiating in depth marker-trait association studies, which will be instrumental for initiating marker-assisted breeding in cotton.

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.

Study of Genetic Analysis of Physiological Attributes under Normal and Drought Conditions in Gossypium hirsutum L.

The aim of this study was to identify the suprior cotton genotypes with improved physiological characteristics under drought conditions. On the bais of root-shoot charcteristics, five genoypes of G. hirsutum were identified as drought tolerant and three genotypes screened out as drought susceptible. The field screening experiment were carried out to validate the findigs of root-shoot screening sudy on the basis of physiological as well as agronomical chracteristics. Both drought tolerant and susceptible genotypes were grown in glass house in pots and followed line x tester mating desighn to cross these genotyps. Parents with their fiftenn offsprings were grown in field conditions in very next cotton season for further analysis. Analysis of variance showed the existence of significant variations among the accessions for all the physiological parameters i.e, osmotic potential, relative water content, cell injury, leaf water potential, excised leaf water loss, stomatal conductance, photosynthesis rate and transpiration rate. Further, among parents line, MS-64 and tester, BH-176 showed superior performance under water scarce conditions. Among the crosses COOKER-315 x Cyto-62 and GS-444 x MPS-11 were better perfomed for high yielding parametrs. The results showed that these two combinations might be helpful to develop drought resistant germplasm on large scale.