| Loblolly pine (Finns taeda), original tree of American southeast, is a very important fast growth tree used as timbering and materials to make paper. For its fast growth, wide uses, strong adaptability and numerous geography variation, it is introduced to many countries and regions. Its forestation areas have exceeded 1 500 000 hectare since introduced to China in 1930s, loblolly pine can be planted in The Changjiang River drainage areas and its south areas that mason pine grows We began to carry through all-sided genetic test in 1980's, did provenance test and built many seed guards. Now it had become an important tree to build fast growth and fertility forest in subtropics of China.Along the development of Fujian forestry, it had become important to meliorate single structure of pine tree and build forestry ecosystem and forestry industry system. In order to accelerate the effective uses of loblolly pine in Fujian province and develop industry material forest of short period, this dissertation did multi-site test of 25 loblolly pine families from domestic and foreign first seed guards in Fujian, compared to slash pine introduced early and native mason pine, evaluated the growth condition of loblolly pine families, studied genetic variation and occurrence of pine brown-spot needle blight diseases, pine-needle rust and pine-needle cast, did physiological and biochemical index , fast growth and stability analysis, and selected some superior families. The main results and conclusions are presented as follows:1.Loblolly pine grow more quickly than slash pine introduced early and native mason pine. Compared to mason pine, The main effective values of loblolly pine families were all positive. By synthesizing clustering analysis, 25 loblolly pine families were divided into 4 groups: best, better, middle and bad. The actual gains were 83.2%, 63.4%, 48.5% and 33.7% respectively.2.There were abundant genetic variation and significant or very significant differences among families of loblolly pine in height, diameter breast-high, crown and volume. This differences were mainly controlled by genetic factors. The variance component of families range from 5.3%~27.6%, which is lower than individual variance component. The genetic variation coefficients were above 4.5%. The broad sense heritability was estimated to 0.42~0.71 for family, and 0.43?.97 for individual. These results are playing important roles on utilization of genetic variation and planning of selection strategy for loblolly pine.3.Heritability of diseases were estimated to 0.26~0.46. Pine brown-spot needle blight diseases happened dispersedly and slightly. Pine-needle rust was at initial stage, and did not affect growth greatly. There were no significant differences in family level. Pine-needle cast varied significantly among families. The correlation coefficients between pine-needle cast and height, diameter breast-high, crown, volume were -0.420, -0.444, -0.561, -0.360 respectively, most of which reached significant level. There were great significant positive correlation among growth traits. This could be important reference for indirect selection.4.There were significant differences among families in chlorophyll, carotenoid and nutrients quantity of needle. The positive correlation coefficient reached great significant level amongchlorophyll and carotenoid quantity. There were middle positive correlativity among them and growth traits. High chlorophyll quantity and low chlorophyll a/b were important reference criterion of selection of fast growth families. Absorption of nutrients N, P, K accelerated one another. Nutrients quantity and growth traits had weak positive correlativity. Nutrient P affected growth speed more greatly.5.Analysis on genetic stability indicated that there were significant or great significant differences in loblolly pine families, sites, gene and site mutual variance. The environment index of 3 sites all reached significant level. Yangkou site was propitious to growth of diameter at breast-height and volume. Nanyu sit...
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