Seed germination and seedling emergence responding to different osmotic potentials and burial depths of 242 Leptochloa chinensis populations

Abstract

Leptochloa chinensis is a troublesome rice weed in many countries, and knowledge of its seed germination ecology varied in different reports. To reveal the range and general characteristics of L. chinensis seed germination under different drought stresses, and seedling emergence under different burial depths, we conducted a serial of germination experiments with 242 L. chinensis populations collected along ranges spanning 4° latitudes and 4° longitudes from rice fields in eastern China. We found that 1000‐seed weight ranged from 0.056 to 0.129 g, with an average of 0.088 g; the OR50 (the osmotic potentials at which the germination percentage reaches 50%) was −0.47 to −0.07 MPa, with an average of −0.28 MPa; and BR50 (the burial depth at which the emergence percentage reaches 50%) ranged from 0.07 to 0.26 cm, with an average of 0.18 cm. At −0.5 MPa, the mean germination percentage of 242 populations was 4.1%. Seed germination percentages under 0.5 and 1.5 cm quartz sand layer were both >75%, while no seedling emerged up to the surface of quartz sand. Populations collected from rice fields in northern regions leaned to be higher in 1000‐seed weights, and OR50 values. Moreover, populations collected from transplanting rice fields slightly and significantly leaned to be more adapted to drought stresses and soil burial depths. The ability to quickly germinate, together with seed germination sensitive to drought stress and seedling emergence sensitive to soil burial, facilitate L. chinensis to avoid suicide seed germination, occupy niches under suitable environments and escape chemical control practices on rice fields.