Early-stage Selection of Drought-Tolerant Rice Seedlings Using PCA Under Mannitol Induced Stress

Drought stress is a major limitation to rice productivity, and its increasing frequency under changing climatic conditions necessitates the identification of drought-tolerant genotypes. The present study investigated the mannitol induced drought response of 20 rice genotypes grown under hydroponics system at the seedling stage. After 21 days stress imposition parameters were analyzed. An increased root elongation but contrastingly decreased root dry weight due to altered carbon allocation was reported in 1% mannitol treated seedlings. While a marked reduction in root and shoot growth and chlorophyll content, reflecting impaired cell expansion and reduced photosynthetic efficiency in 2% mannitol. The principal component analysis was used to screen the genotypes which explained 53.8% of the total variation, and separated genotypes into tolerant, moderately tolerant, and susceptible groups. Genotypes Vandana, FL478, Binnaful, and Katakchikon consistently maintained superior root performance, biomass retention, and physiological stability under stress, whereas IR29, AC-35678, IC-516366 Ravana, and Kangri were highly sensitive. Overall, the integrated evaluation of morphological and physiological traits proved effective for early-stage drought screening and identified promising donor genotypes for rice drought-tolerance breeding programs.