Background: Cotton (Gossypium hirsutum L.) is one of the most significant fibre and cash crops and plays an important role in Indian industrial and agricultural economies. However, over the years quantity and quality have been hampered by the pest leafhopper. Leafhopper alone has been shown to cause yield losses of up to 40%. In this study, screening and evaluation were performed to identify and categorize 100 cotton genotypes along with 5 checks as resistant, moderately resistant, sensitive and highly sensitive to leafhoppers. Results: A total of hundred genotypes were evaluated along with five checks for leafhopper resistance. Based on the screening results, a total of 19 genotypes were resistant to leafhoppers, which was on par with the findings of the check KC 3. The contents of total soluble sugar, total soluble protein, and total free amino acids were significantly positively correlated with the mean grade, whereas total phenols content and trichome density were significantly negatively correlated with the susceptibility grade. However, based on screening and biochemical analysis, the genotypes KC 2, JR-23, Samaru-26-T, D 4, TCH 1728, RS 253, and B-61-1862 exhibited high resistance to leafhopper. Conclusion: According to the findings of this study, choosing genotypes with high total phenolics content together with high trichome density and low contents of total soluble sugar, total soluble protein, and free amino acids may aid in the development of resistant genotypes.

Cotton-melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is emerging as a potential threat to cotton cultivation worldwide. The resistance categories in Gossypium arboreum to A. gossypii still need to be explored. We screened 87 G. arboreum and 20 Gossypium hirsutum genotypes against aphids under natural field conditions. Twenty-six selected genotypes from these 2 species were tested under glasshouse conditions for resistance categories (antixenosis, antibiosis, and tolerance). Resistance categories were assessed by no-choice antibiosis assay, free-choice aphid settling assay, cumulative aphid days using population buildup tests, chlorophyl loss index, and damage ratings. No-choice antibiosis experiment revealed that the G. arboreum genotypes GAM156, PA785, CNA1008, DSV1202, FDX235, AKA2009-6, DAS1032, DHH05-1, GAM532, and GAM216 had a significant adverse effect on aphid development time, longevity, and fecundity. Gossypium arboreum genotypes CISA111 and AKA2008-7 expressed a low level of antixenosis but possessed antibiosis and tolerance. Aphid resistance persisted uniformly at different plant developmental stages studied. The chlorophyl loss percentage and damage rating scores were lower in G. arboreum than in G. hirsutum genotypes, indicating the existence of tolerance in G. arboreum to aphids. Logical relations analysis of resistance contributing factors depicted the presence of antixenosis, antibiosis, and tolerance in the G. arboreum genotypes PA785, CNA1008, DSV1202, and FDX235, indicating their utility for evaluating the mechanisms of resistance and aphid resistance introgression breeding into G. hirsutum to develop commercially cultivated cotton lines.

Cotton (Gossypium sp.) is a commercial crop that is predominantly grown in tropical and subtropical regions, with India emerging as the largest producer globally. This study focused on the genetic diversity and morphological characterization of Gossypium barbadense L., the second most cultivated cotton species. Comprehensive data encompassing qualitative and quantitative traits, spanning morphological attributes to yield-contributing parameters were documented and analyzed using appropriate statistical analysis. The findings indicate the significance of specific attributes, viz., the number of monopodia and sympodia per plant, boll weight and fiber fineness, which emerged as highly reliable markers for selection. These traits exhibit elevated genotypic and phenotypic coefficients of variation, along with substantial heritability and genetic advance as a percent of the mean. Based on per se performance, genotypes SBS 66, SBS 79 and EC 98254 will serve as a source for the selection of parents for improving traits viz., boll weight, upper half mean length, fibre fineness and single plant yield. Principal component analysis divided the total variance into 14 components and cluster analysis segregated the germplasm into 5 distinct clusters, highlighting the substantial genetic variation and the genotypes 3530, CBS 202, ERB 4488 and EGYPTIAN, which can be used as parents in the future breeding programme.

Cotton is a very important crop that consists of traits with different associationship due to genetic and environmental factors. In order to determine the degree of association between seed cotton yield and important traits, a study was done using an RBD experiment with 30 hybrids. Seed cotton yield, plant height, GOT, number of sympodial braches, boll weight, bolls per plant, span length, fineness and strength data were collected and analysed. The experiment was done with 30 F1 hybrids have delivered through Line x Tester mating configuration utilizing six lines and five testers were planted in a Randomized Block Design (RBD) with two replications at the Department of Cotton, TNAU, Coimbatore. Seed cotton yield per plant was found to have significant positive genotypic connection with boll weight (0.5810), number of bolls per plant (0.3867), plant height (0.422) and ginning percent (0.2182) however altogether and contrarily related with consistency proportion at genotypic level. The phenotypic relationship esteems likewise uncovered that seed cotton yield per plant had highly huge and positive phenotypic connection with number of bolls per plant (0.3470) and boll weight (0.4763). Path coefficients were processed to assess the commitment of individual characters to yield in cotton. The way investigation demonstrated high certain immediate impact of number of bolls per plant (0.4743) and fiber strength (0.6880) on seed cotton yield. Micronaire value displayed high sure circuitous impact on seed cotton yield through range length (0.3393), the outcome showed that number of bolls per plant had a high sure relationship with seed cotton yield and sympodial per plant recorded low certain connection with seed cotton yield. It was therefore concluded that selection of high yielding cotton hybrids could emphasize more on lint yield, boll weights, plant height and bolls per plant for better-performing lines. Gin outturn and fibre strength could be used indirectly to improve seed cotton yield through other traits.