Biological characteristics of Leersia japonica (Makino) Honda and its implications for weed management

BACKGROUND Leersia japonica (Makino) Honda is a perennial weed and currently identified as a new dominant weed species in rice fields in many countries, including China. Here, we studied the biological characteristics combined with nonchemical management of L. japonica to develop a proper control strategy of this weed. RESULTS The results showed that 33/28 °C in a 12 h:12 h, light:dark photoperiod were the most suitable growth conditions for seedling regeneration. Salt (NaCl) inhibits the regeneration of seedlings totally at a concentration of 51.3 m m . Seedlings of L. japonica could regenerate in a wide range of pH environments (from 3.50 to 9.50), endowing L. japonica with strong pH adaptability. Osmotic stress also inhibits the regeneration of seedlings totally at −0.13 MPa. A long dehydration time inhibits the regeneration of seedlings; no seedlings could be regenerated for 15 h. With low soil moisture content (33.3% and 50%), the regeneration rate and aboveground fresh weight (FW) were significantly lower than these with high soil moisture content (66.7% and 100%). Stem segments buried in the surface (0 cm) of soil could produce seedlings with the highest regeneration rate (37.5%) and seedling aboveground FW (0.64 g). As the soil depth increased, the regeneration rate and aboveground FW decreased significantly and no seedlings could be regenerated beyond 6.9 cm. CONCLUSION Based on these biological characteristics of L. japonica , creating an environment that is not conducive to regeneration combined with an appropriated tillage system could effectively reduce its occurrence.