Study On The Variation Of Growth Characteristics Of Seedlings Among Families Of Pinus Yunnanensis

Pinus yunnanensis is an endemic and major species in southwest China which plays an irreplaceable role in the maintenance of ecological, economic, and social benefits in the region. Previous research have found lots of fruitful findings in different levels of genetic variation law but lack the theory supporting on growth selection. Meanwhile, a better understanding to the genetic variation laws provides a bridge between the study on Genetic improvement and afforestation by appropriate Provenances and strains. Thus, based on findings of germination, growth and biomass effort and allocation of20families, the paper aims to discuss the germination, growth, growth dynamics and biomass, source of variation, variation and genetic characteristics and attempts to provide the supporting documents to the growth selection of Pinus yunnanensis. The study concluded as follows:(1) The survey of variation:variation varies in different families with respect to8indicators on germination characteristics,4indicators on the growth,7growth parameters on the growth rhythm,9indicators of biomass effort and allocation. Except the germination energy, other indicators showed different degrees of variation among different families; the difference between the germination rate and mean daily germinations (MDG) among families is notable, the difference between the mean time of germination (MTG), the average germination coefficient (CRG), germination index (GI), the difference between the peak value (PV) and germination value (GV) family are very significant. Among one-year families, the difference in respect of crown diameter is significant, that of root length is extremely significant. Among three-year families, the differences in respect of seedling height and ground diameter growth are extremely significant. For the growth parameters on the growth rhythm of one-year seedlings, the difference in6parameters is extremely significant or significant except the T1parameter. The difference among growth parameters on the growth rhythm of two-year seedlings is extremely significant. For one-year diameters, the difference of other parameters is extremely significant or significant except the parameter T2and fast-growing point. For two-year diameter, the difference of parameter T1, T2and the fast-growing point is not significant, but that of other parameters is extremely significant or significant. For the one to two years families, the difference of9indicators of biomass effort and allocation is extremely significant or significant.(2) The source of variations:Except the factor of random error, the variation among families is the dominate factor contributing to the variation of growth traits of20families. The differentiation coefficient of phenotypic traits of8germination indicators are bigger than50%, and the variance components of germination energy is smaller than50%among all8germination indicators. The differentiation coefficient of phenotypic traits of1～3a seedling height are bigger than80%, and the variance components of13.83～29.18%. The differentiation coefficient of phenotypic traits of1～3a diameter growth are bigger than 50%, and the variance components of11.78～27.96%. The differentiation coefficient of phenotypic traits of crown diameter and root length are87.67%and88.69%, the variance components are33.20%and0.49%. A majority of the variance components of7parameters of1～2a seedling height and diameter growth are bigger than20%, and the average of25.78%; the variance components of K of seedling height is the maximum of46.32%during the one-year growth stage; the variance components of K of diameter growth is the maximum of46.32%during the two-year growth stage. The differentiation coefficient of phenotypic traits of9biomass effort and allocation of one-year seedling are among61.57～92.86%, and the average of80.60%, and the variance components of11.78～27.96%. The differentiation coefficient of phenotypic traits of two-year seedling are among57.74～92.86%, and the average of72.09%, and the variance components of12.77～34.03%.(3) The characteristic of variations:Except germination energy, for other indicators, variation among families is the dominant; the degree of variation of germination characteristics of11families (eight indicators average of the CV) is less than the average value. Family No.1showed the worst germination characteristics on differentiation; No.9showed the best. the CV range on seedling height of families of1-3year-old substantially tended to be bigger, starting from8.87%to11.11%then36.74%; indicating that the height growth variation tends to be richer as the growing of the seedlings; the change on the increment of root length CV is greater than that of the crown. for the modular biomass effort and allocation, the variation in the two-year seedling tends to be more severe than that in the one-year seedling; but the family variation contributes more to the one-year seedling in biomass effort and allocation.(4) The Genetic characteristics:Except germination energy, other indicators have0.5more than the genetic force; the germination value (GV) of the families selected manually gets the maximum genetic gain of22.86%. The seedling height and diameter growth of1-3year-old have0.5more than the genetic force, The seedling height growth of the families selected manually gets the higher genetic gain than diameter growth during the difference seedling stage. Family heritability of crown diameter and root length is in the middle level, and the genetic gain gets3.48%and4.32%when the seedlings are selected among the one-year crown diameter and root length the level. For the seedling height growth parameters, the genetic gain gets more when the selection occurs in the second year than that in the first year; for the basal diameter growth parameters, the genetic gains are similar in different years. The genetic force of modular biomass effort is lower than the effort ratio and Shoot to Root Ratio, the effort ratio and shoot to root ratio have0.5more than the genetic force; the ratio of biomass of root material of the families selected manually gets the maximum genetic gain of11.18%at the one-year stage; The shoot to root ratio of the families selected manually gets the maximum genetic gain of14.31%at the two-year stage.