Study On Differences In N Use Efficiency And The Mechanism In New Clones Of Populus Seedlings Under Different N Treatments

Populus in northern China are important green and economic tree species.However,lands in northern China are widespread drought and barren,seriously restricting the survival and growth of populus.Some new clones of Populus have been cultivated in crossbreeding way.On this basis,in a greenhouse that under controlled environmental conditions,we studied nitrogen absorption and utilization of the new clones and their sensitivity to nitrogen,and then explore the reasons of differences in nitrogen use efficiency among clones,to select the new clones of Populus with high efficient use of nitrogen.Finally reveals the mechanism of differences in nitrogen use efficiency among clones.The results showed that at CK or low nitrogen treatments,02-34-334,03-04-111 and 03-04-170 can be able to accumulate a higher biomass,and have higher net photosynthetic rate and water use efficiency,they can adapt to barren soil,strong illumination and dry climate in northern China.The reasons of seedlings can grow normally in the barren lands,are because roots can be able to absorb NO₃^- and NH₄⁺ from soil quickly,especially NH₄⁺.For instance,02-34-334 can absorb NH₄⁺ faster under CK treatment,and be able to accumulate more nitrogen in the stems and leaves than other clones.