Abstract: Promoting sustainable development of improved grassland is an essential way to solve the feed shortage of livestock in ecton areas of Northern China. Irrigation is the key strategy for developing sown grassland. To evaluate the effects of full irrigation vs irrigation during the key growing stage on above-ground and under-ground growth of Elymus sibiricus, field experiments were conducted during 2001-2003 on Bashang plateau in Hebei Province. The results indicated that irrigation observably improved the above-ground biomass and plant height, and the irrigating time played a more important role than irrigating amount as indicated by the results of the irrigation trial during the key growing stage. And it was showed that irrigation also increased root weight density, root length density and the under-ground biomass, although the effect of irrigation treatments on under-ground biomass was not significant.

Key words: Irrigation, Elymus sibiricus, Sown grassland, Growth