| This paper focuses on the selection of introduced Eucalyptus species, provenances, families and clones for plantation management in Guizhou Province, China. Germplasm materials with characteristics of fast-growing, cold-resistance and strong adaptability were selected through overall evaluation of the field experiments for extended planting and promotion; Meanwhile, taking into account the general lack of boron in soils of Guizhou, one of the main factors restricting eucalyptus growth, a test of application of boron at different concentrations was carried out to find out the appropriate rate of application of boron by analizing the growth traits and nutrient contents of the leaves of Eucalyptus tree species. In addition, the effects of fertilization at different seasons were studied to find out the proper fertilizatiing seasons for eucalyptus plantations. All these studies provided Guizhou with good planting materials, appropriate rate of fertilizer applications and low risk of planting for the development of Eucalyptus plantations. The results of the studies are summarized below:(1) Eucalypts were first intrduced into Guizhou more than 70 years ago. Among the species introduced in 1960s, only three species, Eucalyptus robusta, E. citriodora and E. exserta, are survived in river basins of Liujiang, Nanpanjiang and Hongshuihe rivers in Southern Guizhou with comparitive rich in heat resources as they are not cold-resistant. E. globulus, a species introduced in 1990s, can survived in Southern and Central Guizhou as it is more cold-resistant.(2) The results of analysis of variance (ANOVA) of yearly grwoth traits and form quality traits conducted for 19 species/provenances with more than 50% survival rate in a species/provenance trial and 13 species/provenances in two species/provenance trials showed that the grwoth traits and form quality traits were significantly different. At the age of 39 months, 8 species/provenances, Eucalyptus dunnii, E. saligna Smith, E. grandis Seedlot No.13023, E. globulus, E. citriodora and three provenance of E. urophylla, were selected through eveluation by using synthetic index method. Analysis of statability of growth performance of trials plantations at two sites reaveled E. saligna was the most unstable,which performed well in fertile soil with high water content, followed by Eucalyptus dunnii, provenance 10144 of E. uroppylla and provenance 13023 of E. grandis which performed well under good environmental conditions. Provenance 17841 of E. urophylla, the provenance most suitable for extensive growing, is less cold-resistant and careful selection of planting sites is needed for extended planting. Provenance 20758 of E. grandis performed well in infertile soils.(3) E. dunnii provenance/family trials was established in Central Guizhou, the survey of tree high growth rhythms showed that the growth curves of 15 provenances tend to be bimodal. E. dunnii started to grow fast in May and reach the peak in early July, while slowdown from late July to early August when the temperature is high and rainfall is low in the trial area; the second peak period of growth occurs in August with increasing rainfall, and then growth becomes slowly due to the decreasing rainfall amd low temperature. Water and heat balance seems to be the basis of maintaining the fast-growing E. dunnii Maiden.The ANOVA of growth traits of 78 families of 15 provenances showed that tree height, DBH and individual volume among provenances and families were significantly different. The heritability of the tested familis is 0.0322-0.3535, a low to medium heritability indicating that the traits are less affected by genetic control but by environmental influence. The heritability of the traits is bigger in famililies than in individuals, this means that larger genetic gain can be obtained while selection is conducted at familiy level. Three provenances are selected according to the standard deviation method, the genetic gains are 3.543-11.983%;9 families or 11.53%, are selected with genetic gainsof 0.446-9.913%.(4) The ANOVA of yearly growth traits of 174 clones in the clonal test I indicated that all the growth traits among clones were significantly different. At the age of 4.5 years, 11 fine clones having the individual volume more than the widely cultivated clone DH32-29 were selected. In clonal test II, 4 clones were selected from the 5 ever-selected clones and 4 ever extensively planted clones with individual volimes heigher than the average of the tested clones, of which 2 have not been widespread, thus providing the local people with more lanting materail.(5) Eleven fine clones directly introduced from south China were planted at two sites at two altitudes. Experimental results showed that superior to that at low altitude. The average tree height, DBH, individual volume and stand volume of trees at high altitude is are 12.51%, 34.47%, 109.04% and 89.13% higher than tose at low altitude, respectively. The best clone is Eg5 clone with an annual syand volume of 45.66 m3 / hm2, which is 11.7% - 87.5 % higher than the other clones. Analysis of statibility reaveled that the regression coefficient (bi) of 5 clones, Eg5, DH32-29, GL-9, DH32-22 and Eg6,which recorded higher stand volumes than the average, is more than 1, showing that better clone genotype and site conditions are resulted in better tree growth performance.(6) Correlation analysis of yearly growth traits of clones in the above three clonal tests at early stage and later stage showed that better growth prediction can be made with use of growth traits at the age of 2.5 years.(7) Results from a study on the effects of application rates of boron on the growth performance of Eucalyptus urophylla x E. grandis showed that the height and DBH of six-month-old young trees in plots applied with boron were significantly higher than those in the control, indicting that applicantion of boron benefits the early growth of Eucalyptus urophylla x E. grandis. The differences in DBH of young trees among plots applied with different rates of boron were not significant, while those in tree height were significant. At the age of 2.5 years, tree height in plots applied with higher rates of boron was higher than that in plots applied with lower rates of boron; and the greatest height growth was recorded in the treatment of L5. Low applicaion rate of boron resulted in high mortility of young tress, and thus provided the survived trees with more growth spaces which may lead to greater rates of growth of DBH and height of individual trees during the late stage of growth. At the age of 4.5 years, the greatest standing volume was recorded in the boron application treatment of L10, follwed by L5. Application of boron at 5-10 g per trees resulted in increasing standing volume by 44.72-64.56% and better stem forms and branching.(8) Fertilization trials of clone DH32-29 at different rates and in different seasons indicated that fertilization in Winter can lead an early fast growing stage, a longer growing period and higher productivity of Eucalyptus trees than fertilization in Summer, even the fertilization rate is low. This may be due to the loss of fertilizers resulted from soil errosion caused by heavy summer rains. The annual individual volume of clones reached the peak when fertilization rate is 300g (F2) without increament with increasing fertilization rate. At the age of 2.5 year, the individual volume of high fertilization treatment F5 (450g) is the least, only slightly higher than the control, indicating that too high rates.of fertilizer application do not promote eucalyptus growth, or contrary inhibit growth potential.
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