Multivariate analysis to identify drought responsive morpho-physiological traits in standard chrysanthemum genotypes

Chrysanthemum is a major flower crop grown globally for its use as cut flowers, potted plants and landscape decoration. It is highly susceptible to drought; hence, it is necessary to identify the drought responsive key traits in chrysanthemum. In this study, 14 standard chrysanthemum genotypes were evaluated for drought tolerance under hydroponics and pot culture in three replications of a completely randomised design (CRD). The seedlings were exposed to osmotic stress with 10% PEG (Polyethylene Glycol). In pot culture, a drought stress of -60 kPa was applied for seven days during the vegetative growth and flower bud initiation stages. R statistical analysis was performed (PCA analysis, R2.15.1 by R Development Core Team) to evaluate several morphological and physiological traits. In hydroponics and pot culture drought conditions, RWC, MSI, and yield were highly correlated with chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, chlorophyll fluorescence, stem girth, flower yield, and biomass. As a result, these traits can be considered useful selection indicators for drought tolerance. According to PCA, the traits chlorophyll a, chlorophyll b, chlorophyll a/b, total chlorophyll, carotenoids, RWC, and chlorophyll fluorescence were the most crucial traits that involved in genotype variability under stress contributing significantly to PC1 in pots and hydroponics. In hydroponics and pot culture, the variability was categorized into three and five principal components, respectively. These results offered useful information for chrysanthemum breeders aiming to select and improve drought tolerance through targeted selection and marker-assisted breeding strategies.