Productivity of Hybrid Rice: I. Vulnerability to Water Stress of Reproductive Development and Inhibition of RuBisCO Enzyme in Upper Leaves as Major Constraints to Yield

Abstract

Producing more rice (Oryza sativa L.) with less water is a formidable challenge for the food, economic, social, and water security. To achieve this, the knowledge of how plant water stress is transduced into plant performance is necessary. The objective of this research was to investigate in hybrid rice the impact of soil water deficit, especially on reproductive growth and photosynthetic activities that lead to the ultimate harvestable product—grains. The early reproductive growth period, encompassing tetrad-formation stage of meiosis (i.e., about 10–15 d prior to heading), was found to be the most sensitive and critical to water deficit resulting in up to 59% grain sterility that caused similar magnitude of yield reduction. As the grain formation progressed further, the early period of grain-filling was found to be more vulnerable to water stress than the late-milk stages. The behavior of upper leaves appeared to be conspicuously at variance under water stress in that the survival of flag leaf dropped f...