Abstract:By setting up a controlled-experiment with soil water content and fertilizer,the seedling were analyzed to investigated the effects of environment on the trade-off and lignification and to understand the reasons and mechanism of the seedling and the seed regeneration.The results showed that:(1)Populus euphratica seedling’s growth of trade-off was mainly reflected in biomass distribution strategy.However,the main root length to height ratio was not significantly different.(2)Under continuous water treatment,drought stress increased root to shoot ratio.The root to shoot ratio of the 15% water content level increased by about 75% and 93% of those under 20% and 30% water content levels.But drought stress decreased biomass,for example,the biomass of 10% water content level decreased by about 53.4%,89.2%,78.6% than other levels.With intermittent water treatment,drought stress also increased root to shoot ratio.The root to shoot ratio of the 15% water content level increased by about 34% and 38% of those under 20% and 30% water content levels.In addition,drought resistance can also impact lignification with both water treatments.(3)Applied nitrogen and phosphorus could improve root to shoot ratio and lignification significantly,but excessive nitrogen decreased biomass.The sensitivity of P.euphratica seedlings to water and fertilizer conditions and the growth weighed ability are key factors to create seeds and maintain population.Therefore,the soil water and fertilizer conditions play an important role for the seed germination and seedling growth of P.euphratica.