Principal Component Analysis Of Morphological Traits In Cotton Genotypes Under Heat Stress

https://doi.org/10.5281/zenodo.17876924

Abstract

Heat stress is among the primary abiotic factors that suppress cotton productivity globally, especially during the initial seedling growth stage. To evaluate morphological responses and determine the main characteristics of heat tolerance, six cotton genotypes were studied under controlled high‑temperature conditions. Morphological parameters including shoot length, root length, number of leaves, fresh weight, and dry weight were measured and subjected to principal component analysis (PCA). The findings indicated that the first principal component (PC1) accounted for 97.97% of the total variance, with uniformly negative loadings across all traits, suggesting that PC1 represents overall growth and biomass reduction under heat stress. PC2 explained 1.75% of the variance and was dominated by the number of leaves, separating leaf production from biomass traits. Later components (PC3–PC5) contributed less than 0.2% each, reflecting minor trait‑specific variations. The scree plot revealed that the dominant stress response was captured in PC1, whereas the biplot showed clear separation of genotypes along Dim1 and Dim2, with shoot length and fresh weight exerting the strongest influence. These results imply that biomass reduction and leaf production are the most important indicators of heat stress resistance in cotton seedlings. PCA therefore serves as a robust multivariate model for differentiating tolerant and susceptible genotypes, providing crucial input for breeding programs aimed at enhancing cotton resilience under rising global temperatures.