Photosynthesis and panicle growth responses to drought stress in F_1 hybrid rice (Oryza sativa L.) from a cross between thermo–sensitive genic male sterile (TGMS) line 103S and upland rice IR17525

Abstract

An F1 hybrid rice combination from a cross between a thermo-sensitive genic male sterility (TGMS) '103S' line and an upland rice 'IR17525' were investigated for physiological response traits under drought stress and recovery at the heading time by comparing with its parents. The F1 and parental plants were planted in pots in a net house at different times for synchronizing flowering. At the stage of 5-3 days before heading, water was withdrawn from the pot. When the soil water potential in the pot reached -60 kPa, pho- tosynthetic rate and dry matter accumulation were measured. Recovery traits including photosynthetic rate and dry weight of panicle were measured at 5 days interval until harvesting. The results showed that the photosynthetic rate was lower in the F1 hybrid than that in the parents during drought treatment, in contrary it was higher during recovery stage. The grain yield was maintained in the F1 hybrid under drought treatment as much as under the control condition, whereas it significantly reduced as drought treatment in the male parent. The grain yield was higher in the F1 hybrid than that in the male parent under the well- irrigated condition, and even much higher under drought treatment. It is suggested that such advantageous characters, including the shorter ripening duration, the longer panicle exertion, the higher recovery photo- synthetic rate as well as the faster of dry matter translocation into panicle at the ripening stage, contribute drought tolerance in rice. Thus, the F1 hybrid rice 103S/IR17525 would be a promising rice with high yield potential under drought stress.