Root Response to Drought Stress: Insights from Peg-Induced Patterns in Rice Germplasms

Drought stress threatens rice productivity, especially in South Asia, where climate variability exacerbates water scarcity. This study investigates root growth responses in 29 rice germplasms (7 varieties, 22 landraces) from the drought-prone Red-Lateritic Zone of West Bengal, India. Using polyethylene glycol at four different concentrations (i.e. 0%, 5%, 10%, and 20%), stress was induced and root growth of each germplasm was monitored over 10 days. Four distinct root growth patterns emerged: Pattern 1 showed the highest average root length (ARL) under control, with reductions of 33.68%, 57.72%, and 97.79% with increasing stress. Pattern 2 exhibited a sharp initial decline (~50%) that stabilized across higher stress levels. Pattern 3 displayed a decrease in mild stress, followed by a gradual increase in ARL under moderate and severe stress. Pattern 4, unique to the landrace Kalpana, showed an ARL increase under mild stress surpassing control, but ARL dropped to zero under severe conditions. These patterns highlight diverse root adaptations to drought. This study offers insights into breeding strategies to enhance drought tolerance through targeted root traits in rice.