|HENRY, CHRIS - UNIVERSITY OF ARKANSAS|
Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/19/2018
Publication Date: 10/16/2018
Citation: Barnaby, J.Y., McClung, A.M., Rohila, J.S., Henry, C.G., Ziska, L.H., Sicher Jr, R.C. 2018. Interspecific variation in physiological and foliar metabolic responses to reduced soil water availability. In: Proceedings of the 37th Rice Technical Working Group Meeting, February 19-22, 2018, Long Beach, California. p 77.
Technical Abstract: Climatic uncertainty, particularly in regard to water resources, may alter irrigation management of rice, an essential cereal grain acknowledged as the primary food source for more than half the world’s population. To reduce water use, an alternate wetting and drying (AWD) system has been developed, but understanding the impact of water stress on physiological and metabolic responses controlling grain production is needed. Among two known critical yield reduction stages, i.e. the transition phase from vegetative to reproductive stage and the grain fill stage, the former stage, in relation to grain production, is largely elusive. Seven cultivars displaying different yield responses to water stress were grown under four different continuous irrigation levels applied using a sub-surface drip irrigation system to understand physiological and metabolic responses to different stress levels at the transition stage. Our objectives were twofold: (1) to evaluate cultivar differences in physiological and metabolic responses to four irrigation treatments varying 0 , 30, 70, or 95% water deficit; and (2) to assess whether these changes were associated with variation in yield. Cultivars that had relatively stable yields in response to water stress, i.e. Saber, Kaybonnet, and Francis, had the distinctive physiological responses as compared to the high responsive cultivars, PI312777 and Teqing, under the moderate stress condition (70% water deficit). In addition, non-responsive cultivars accumulated stress-induced carbohydrate metabolites even at mild and moderate stress conditions (30 and 70% water deficit, respectively) whereas for highly responsive cultivars this was observed only after a moderate stress condition. Overall, these data suggest that cultivars, with physiological stress indicators, i.e. A, gs, SPAD, and leaf Tm, detected under the mild stress condition (30% water deficit), accumulated carbohydrate metabolites, known as osmolytes, as compared with the other cultivars. Furthermore, those cultivars, Saber, Francis, and Kaybonnet, displayed relatively stable yield production upon water stress regardless of their yield potential under fully irrigated conditions.