Abstract: By using the modified relay seeding technique,more than 10 allelopathic rice materials were obtained from 500 rice germplasm,and their allelopathic inhibitory effects on weeds were evaluated under field condition.The results showed that under direct-seeded condition,the allelopathic rice materials Gumei 2,Xiayitiao,Jizaoxian,Ganzaoxian and Shangnuo 1 had more obvious inhibitory effects on Echinochloa crus-galli than non-allelopathic rice materials Xiushui 63 and Chunjiang 11,while the allelopathic rice material Milyang 54 had the best inhibitory effect on field weeds.Under field-transplanting condition,the allelopathic rice materials Gumei 2,Qingkun 1,Xiayitiao and Jizaoxian had significant inhibitory effects on Echinochloa crus-galli over non-allelopathic materials Xiushui 63 and Chunjiang 11.There existed significant differences in some agronomic characters among rice materials.Allelopathic rice materials Xiayitiao and Jizaoxian had higher plant height and stronger tillering activity,but had smaller leaf areas of the 3 upper leaves.

Key words: Rice germplasm, Relay seeding technique, Allelopathy, Field evaluation, Agronomic characteristics