Genetic Variations And Early Selection Of White Elm In Half-sib Families And Among Clones

Eighteen white elm(Ulmus pimila linn.)half-sib families and twenty clones at ten year's age have been studied on the genetic variations of 21 growth, morphological, physiological and biochemical characters. They are height, chest diameter, the height of trunk, branch diameter, branch angle, the total number of branches, the width of tree crown, area, fresh weight and dry weight of single leaf, the ratio of leaf fresh weight to dry weight, the content of chlorophyll a, b and the total content of chlorophyll, N, P and K content in leaves, photosynthesis rate, transpiration rate, stomatic conductance and the concentration of CO2 between cells. Comprehensive analysis has been made for these 21characters in order to reveal the internal inheritible mechanisms and to provide scientific basis for early selection and evaluation.Variance analysis and multiple comparison indicate that differences in all characters of white elm half-sib families and clones are significan at 0.05 level or 0.01 level except for the ratio of fresh weight to dry weight among half-sib families. The variation coefficients of most traits are greater in half-sib families than that in clones except for several branch traits.The average height of clones is nearly two meters higher than that of half-sib families, and the average volume of clones is 1.16 times about that of half-brethren families. The chest diameters of most clones are greater than that of the half-sib families. The average values of most traits of clones are greater than that of half-sib families except for the content of chlorophyll and the concentration of CO2 between cells. The hereditability of all characters of half-sib families lies between 0.459 to 0.718, which is obviously smaller than that of clones. The hereditability ofmost characters of clones is over 0.8 except for dry weight and transpiration rate. The hereditability of chest diameter is the largest both in half-sib families and clones.N, P and K are three necessary nutritive elements of all plants, which are very important to the growth of plants. There are few reports about the correlation between them and volume growth. It has been found that the contents of N and P in leaves are all positively correlated with volume growth.By the correlation analysis, main component analysis and cluster analysis of the tested parameters with volume growth, the characters showing significant correlationship with the volume are as followings : height, chest diameter, the height of trunk, the total number of branches, the width of tree crown, the contents of N, P in leaves and photosynthesis rate. It is suggested that these characters could be consideredd as early selection and evaluation indexes of white elm.