| In this study, P. deltoids×P. simonii was taken as the main study object. Through experiments in the fields of growth rythem of seeding stage, drought stress, photosynthetic characteristics and anti-pest activity, the differences in seedlings were discussed, which preliminarily provides some theories for high, quality high yield and efficient breeding. A sum-up of the main conclusions is given below:(1) The variation coefficients of seedling height and floor diameter were 14.86% and 19.44%, respectively, while the broad-sense heritabilities each were 0.533 and 0.486.(2) The growth of seeding stage presents a "slow-fast-slow" trend. Logistic equation properly simulated the curve of seeding stage growth. The process of seeding stage growth was divided into four periods: survival period of cuttings, pre growing, fast-growing and slow-growing periods of seedlings.(3) Several guide lines of drought resistance were comprehensively evaluated by fuuzy subordination method. The drought resistance activities of tested poplar were: clones 24# >9# > S > 8# > 29# > 19# > 6# > 2# > T > 1#.(4) All 32 clones were uninfected by acarids. Taking advantage of cluster analysis, clones could be categorized into highly disease-resistance type, mild susceptible, moderate susceptible and highly susceptible types. Clones 12#, 19#, 22#, 24# and 31# showed especially high activities of leaf-rust resistance.(5) The analysis of principal components showed that the growth of P. deltoids×P., simonii were chiefly influenced by comprehensive growth factor, comprehensive effective factors of the duration of seeding stage growth, leaf-rust resistance and photosynthesis. Based on the analysis of principal components together with various factors such as growth and anti-pest activity, clones 2#, 19# and 31# with high growth and high acarid and leaf-rust resistance were ultimately selected.
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