Differential response of chrysanthemums on osmolyte accumulation, chlorophyll content and growth attributes under salinity stress

Chrysanthemum is moderately sensitive to salt stress, and salinity largely affects its production. The experiment was undertaken at the research farm of the Division of Floriculture and Landscaping, ICAR-IARI, New Delhi, during the winter season. Ten chrysanthemum varieties were screened to understand their response to salt stress (150 mM NaCl) and tolerance mechanisms. Salt stress significantly affected osmolyte accumulation and physio-biochemical attributes of chrysanthemum varieties against control. Red Gold variety performed well in terms of growth and yield attributes, indicating its ability to tolerate the salt level of 150 mM NaCl. The highest leaf proline content was recorded in var. White Prolific followed by var. Tata Century. NaCl stress caused a 3/2-fold and 1/2-fold increase in the level of Na+ and K+ ions in leaf tissues of most varieties against control Shoot K+/Na+ ratio was recorded highest in variety Tata Century followed by variety Discovery. From the experiment, vars. White Prolific, Red Gold, Tata Century, and Discovery were found to be more tolerant due to better osmotic adjustments through the accumulation of proline, relative performance under salt stress for plant growth, flower yield, photosynthetic pigments and high K+/Na+ concentration to better sustain under saline condition than the susceptible varieties. PCA analysis revealed that the sum of principal components PC1 and PC2 explained 59.0% of the variations among the varieties. Plant height, chlorophyll content, and fresh weight number of branches had the highest positive loading value, i.e., ~0.7, and leaf proline content had the lowest loading value, i.e., ~0.08, indicating the strongest influence on PC1 and PC2.