Comparative Study of the Performance of Selected Rice Genotypes in terms of Root Attributes under Stress and Non- Stress Conditions in the Vegetative Stage

Abstract

Rice (Oryza sativa L.) is one of the largest staple food crops worldwide, particularly in Asia. Abiotic factors such as drought stress are a key factor that has reduced the yield of rice, especially at the initial stages, and the root system architecture is also significant in adaptation of plants to water – stress conditions to increase its ability to gain water and nutrients. In this study, the drought tolerance of plants at the vegetative stage was assessed in ten rice varieties, such as IR116713D, Bg 374, IRRI 264, Bg 22 – 3434, IR21C1106, IR21C1071, IR21C1100, Bg 377, IR93980S and IR21C1061. Among the chosen rice lines, Bg 374 and Bg 377 are released as cultivars in Sri Lanka, but other rice lines are still not released but have a possibility of later evaluation under local agronomic conditions. Drought stress caused notable impact on root length and root volume with stress conditions generally facilitating the promotion of root development although the responses of the varieties differed depending on the genetic variation in the drought tolerance. Root length and root volume were measured at 45 days after using root scanner (WinRHIZO model). Drought stress significantly (p<0.05, ANOVA) affected root traits, with genotypic variation. IR21C1071 exhibited the greatest root elongation (12.3 cm), while IR116713D showed the highest root volume increase (11.4 cm³), reflecting superior adaptive capacity under stress. IR21C1071 and IR116713D are promising donors for breeding programs targeting drought-prone environments. Variation in root architecture, particularly elongation vs. volume expansion, provides a basis for selecting resilient rice genotypes at the vegetative stage.