Priming Effect of Rice Seeds on Seedling Establishment under Adverse Soil Conditions

An experiment was carried out to find out the priming effects of rice seeds, Oryza sativa L. (cv. Ilpumbyeo) on. the seedling establishment and early emergence under excess soil moisture conditions. Seeds were primed by soaking in -0.6 MPa polyethylene glycol (PEG) solution at $25^{\circ}C$ for 4 days. The primed seeds were sown in soils with various soil moistures (60, 80, 100, 120, and 140% field capacity) at 17 and $25^{\circ}C$, respectively. Germination and emergence rates, plumule height, and radicle length of primed seeds were higher than those of untreated seeds at any soil moisture and temperature examined. The time from planting to 50% germination ($T_{50}$) of primed seeds was less than that of untreated seeds by 0.9～3.7 days. Germination rate, emergence rate, plumule height, and radicle length were highest at the soil moisture of 80% field capacity among the soil moistures. Priming effects of rice seeds on germination and emergence rates were more prominent under the unfavorable soil moistures (60, 100, 120, and 140% field capacity) than those under the optimum soil moisture condition (80% field capacity). However, priming effects on seedling growth were greater at near optimum soil moisture compared with too lower or higher soil moistures. Therefore, these findings suggest that priming of rice seeds may be a useful way for better seedling establishment under the adverse soil conditions.