Adaptability of Eragrostis japonica to different environmental factors and screening of herbicides for its control

Eragrostis japonica is one of the malignant gramineous weeds in paddy fields. To clarify the main environmental factors affecting the seed germination of E. japonica, the Petri dish and pot methods were conducted to determine the effects of temperature, light, pH, salt stress, osmotic potential, and sowing depth on seed germination. In addition, 27 herbicides were evaluated for the control of E. japonica. The results showed that the seeds could germinate at 20～40 ℃. The temperature of optimum germination was 35 ℃ under constant temperature and 35 ℃/25 ℃ under variable temperature. The seeds of E. japonica were light-sensitive, and it was difficult for seeds to germinate in its absence. When the pH was between 4 and 10, the seed germination rate was above 80.67%. With increasing NaCl concentration, the seed germination rate tended to decrease. When the NaCl concentration reached 160 mmol·L⁻¹, seed germination stopped. Seeds of E. japonica were sensitive to osmotic potential, with the germination rate being inhibited by 50% when the osmotic potential was -0.35 MPa. When the sowing depth reached 8 mm, the seed germination could be completely inhibited. We found that at the recommended dosage, 11 pre-emergence herbicides (oxyfluorfen, oxadiazon, butachlor, clomazone, mesotrione, pretilachlor, anilofos, pendimethalin, butralin, prometryn and pentoxazone) had high activity. Overall, the inhibition rate of the fresh weight was more than 96.28%. The fresh weight inhibition rate of five post-emergence herbicides, viz. metamifop, thiobencarb, propanil, pyraquinate, and pheprodim, on E. japonica ranged between 92.16% and 99.36%. These results provide a reference for the chemical control of E. japonica in paddy fields.