Abstract: 【Objective】 To determine the germination characteristics of Johnsongrass (Sorghum halepense), a worst exotic weed species, 【Method】 the effects of glume, temperature, light, GA3 and soil depth on seed germination were studied. 【Result】 The results showed that the glume of Johnsongrass had mechanical obstructing and chemical inhibiting effects on seed germination, and it was the major cause of seed dormancy. Germination of Johnsongrass seeds was best at 30℃, and also better under the daily temperature change of 25℃/35℃ for 12 h/12 h. Light was preferred for seed germination, the rate was relatively higher under 12 h light or continuous light condition. GA3 could significantly stimulate the germination of Johnsongrass seeds and the optimum concentration was 1.16 mmolּL-1. Seeds placed in 0~4 cm soil layer was ideal for germination of Johnsongrass, but the germination rate decreased markedly with the increase of soil depth. 【Conclusion】 By implementation of corresponding management strategies to regulate and prevent the seed germination, the spreading and infestation of Johnsongrass could be well controlled.

Key words: Sorghum halepense, exotic weeds, seed, dormancy, germination