EFFECT OF SUBMERGENCE ON PHYSIOLOGICAL INDEXES AND YIELD COMPONENT AT REPRODUCTIVE STAGE IN RICE

Some phyisological indexes, growth development indexes and yield components were investigated comparatively under complete plant submergence stress at booting and milk stages of rice.It had been shown that net photosynthetic rate of the treated leaves was decreased, chlorophyll content was decreased at booting stage, but little affected at milk stage, electric conductivity increased markedly due to efflux of electrolyte from injured cells, proline content increased obviously.The bleeding sap of root system reduced, but contents of its major amino acids e.g., Ala, Pro, Phe increased.Soluble sugar of leaf sheath dropped.Plant height raised slightly, but the fourth internode elongated significantly.As time of submergence stress was prolonged, the number of green leaves on a stem were lowered, necrotic rate of tillers was increased, tiller rate on high nodes was raised distinctly, duration of growth was delayed.The reduction of grain yield was resulted from decrease of effective tillers per hill, increase of empty grain ratio, decline of thousand grain weight.