Response of Architecture and Functions of Roots in Three Kinds of Sweet Gums Under Drought Stress

With the three kind of two-year-old Liquidambar seedlings: Liquidambar formosana, Liquidambar acalycina and Liquidambar styraciflua as study object, studying the influence of natural drought on conformation and functional characteristics of Liquidambar seedling root system, by using a randomized complete block experiment. The results showed that except the carbon content, the difference of all indexes in all treatments(including seed and drought treatment) was significant(P 0.01) under the drought stress, the relative growth rates of specific root length, specific surface area and root bifurcate of the Liquidambar acalycina were the highest, which reached to 56%, 30% and-4% respectively; which of Liquidambar styraciflua were the lowest, reached to 9%,-3% and-19% respectively. While the relative growth rates of Liquidambar styraciflua root density and roots average diameter were the highest, which reached to 40% and-10% respectively, which of Liquidambar acalycina were the lowest, reached to-27% and-16% respectively. The relative growth rate of the Liquidambar styraciflua root system nitrogen content was the highest, which reached to 127%, which of Liquidambar formosana was the lowest, reached to 41%. The relative growth rate of Liquidambar formosana C/N was the highest, which reached to-26%, which of Liquidambar styraciflua was the lowest, reached to-56%. The results also indicated that the rootlet at 0d0.5mm had a significant contribution in seedling stage, especially Liquidambar styraciflua. The drought resistance strength of three kinds of root system was in the order: Liquidambar formosana Liquidambar styraciflua Liquidambar acalycina.