Evaluation of near‐isogenic lines of rice introgressed with submergence tolerance and deep rooting at early growth stage

Abstract

Rice varieties that minimise shoot elon- gation under submergence and provide tolerance for up to two weeks carry SUB1A. Conversely, DRO1 responsible for deep-rooting, helps in water and nutrient acquisition under drought. In this study, we compared the growth of NIL-SUB1, NIL-DRO1, and NIL-SUB1DRO1 with IR64 background for its dual tolerance to submergence, drought, and recov- ery. Submergence was on 14- and 16-days old seed- ling for 7 and 10 days and allowed to recover for 7 and 10 days respectively. Drought was also imposed on 14- and 13-days old seedlings for 18 and 29 days followed by 10 days recovery respectively. Submer- gence and drought adversely affected growth and performance of the genotypes. Compared to IR64, NIL-SUB1DRO1 suppressed shoot elongation during flooding, maintained the function of the leaf photo- system, and under drought conditions, maintained leaf water potential and contributed to increased dry mat- ter weight of shoots and roots. In addition, NIL-SUB- 1DRO1 exhibited deep rooting, with roots extending into the lower subsurface layers under drought condi- tion. It is suggested that NIL-SUB1 showed potential tolerance to submergence and NIL-DRO1 to drought. Furthermore, NIL-SUB1DRO1 was found to be toler- ant to both drought and flooding.