Physiological characterization of introgression lines derived from an indica rice cultivar, IR64, adapted to drought and water-saving irrigation

Water scarcity threatens sustainable rice production in many irrigated areas around the world. To cope with the scarcity, aerobic rice culture has been proposed as a promising water-saving technology. The objective was to elucidate the physiological attributes behind the performance of rice introgression lines in water-saving culture. We evaluated yield potential and physiological adaptation traits to water deficit of BC3-derived lines with the genetic background of an elite indica cultivar, IR64, in the field and in pot experiments. One line, YTH183, had 26% higher yield than IR64 under non-stress conditions (895 vs. 712 g m−2 on average). This was attributed to enlarged sink capacity due to large grain size, which contributed to more efficient use of assimilates and hence a higher harvest index. YTH183 also showed better dehydration avoidance under intermittent soil drying, due to the adaptive response of deep rooting to water deficiency. The grain yield of YTH183 exceeded that of IR64 by 92–102% under moderate water deficit caused by limited irrigation in aerobic rice culture (143 vs. 72 g m−2). Two introgressed segments on chromosomes 5 and 6 might, at least in part, confer the higher yield potential and greater dehydration avoidance in YTH183 simultaneously. Advanced backcross breeding combined with molecular genetics and physiological characterization of introgressed segments would be effective for developing new rice cultivars with high yield potential and drought adaptation traits.

► We identified one advanced backcross line (YTH183) with the genetic background of a mega-variety, IR64, suitable to aerobic rice culture.
► YTH183 had a yield advantage over IR64 by an average of 26% under non-stress conditions (895 vs. 712 g m−2).
► YTH183 yielded 92–102% more than IR64 under moderate water deficit in aerobic soils (143 vs. 72 g m−2).
► Greater performance of YTH183 than IR64 in aerobic rice culture would be attributable to higher harvest index by enlarged sink capacity and better dehydration avoidance by deep rooting.