A Study On Early Selection Of Superior Families And Plus Indivaduls Of Pinus Yunnanensis

Pinus yunnanensis is one of main forest vegetation types with pivotal function in economic development and ecology construction in Yunnan Province. However, the process of genetic improvement is postponed by long-term"larger-selection cutting"resulted in genetic deterioration and descendant individual division, and slow growth serious disease (especially cataplexy) in seedling period. In order to change this situation, many works are accomplished in sexual improvement, such as provincial selection and the construction of seed garden, growth incremeant and form quality of filial generation are obviously improved, and the rich genetic material is provided for asexual improvement. But the same problem with other coniferous trees existences in P. yunnanensis, such as long time for seed garden construction, slow efficiency and low seed yield. Much studies show that early selection has an important function for shortening breeding cycle and enhancing genetic gain in per unit time, and it has the certain effectivity and feasibility. Determining the age of early selection is a key problem for enhancing selection reliablity and seedling selection is the efficient path for shortening the breeding cycle. Based on the material of analytic trees of P. yunnanensis, the suitable age and the best age of early selection are determined by juenile-mature correlation analysis of height growtrh increment and the early choice efficiency of different rotational age. And on the bases of variance analysis and the multiple comparisons of inter-family and intro-family with 1 year seedling of 54 pedigree and 1~3 years seedling in mixed pedigree, the suitable standard for plus seedling sselection proposed. And the plus family and the plus seedling are selected by single index of growth character and comprehensive indexes of growth character and the disease-resistant ability, and the material for cutting orchard is provided. The main results are as follows:(1) The correlation coefficient of height growth increment between year and year tends to be stable as the increasing of tree-age. The correlation coefficient of height growth increment between 1~7a and orther age's presents great significant level, significant level and un-significant level, that of 8~11a displays great significant level, significant level. And after 12a, the correlation coefficient of height growth increment between year and year become great signifcant.(2) The efficiency of early selection among different rotation increases as the increasing of population age, the efficiency increases and then decreases as the increasing of population age in a same rotation. Moreover, the efficiency of the different rotation is more than 1. This results show that the efficiency of early selection is higher than that of adult selection.(3) Taking the age of highest selection efficiency for the best age of early selection and taking the age of more than 95% highest efficiency for the suitable age of early selection, the best selection age is 2a and the suitable selection age is 2~4a when the rotation is lower than 20a, the best age is 3a and the suitable age is 2~5a when the rotation higher than 20a.(4) Individual growth increment of height, basal diameter and disease resistance ability among families and within a family show a great significant difference, this rule indicates that the heredity difference is decided by the parents'genetic characteristics. The results also show height increment difference is more important than that of basal diameter, and height and basal diameter increment present a significant positive correlation ( r=0.587, P<0.01). This rule indicates that the early selection should be taking height increment for mian factor and taking basal diameter increment for auxiliary.(5) 21 families are selected by height growth increment, 19 families are selected by the growth increment of basal diameter, 22 families are selected by disease-resistant ability. And 21 families are selected by the combined indexes of height growth increment, basal diameter growth increment and the ability of disease resistance, and the selection rate is 38.9%.(6) On the bases of fine families, 226 plus-seedling is selected with the aim of faster growth, stem straight and the apical dominance, and with the standard of average height adding standard deviation, and the selection rate is 16.2%. Meanwhile, 3520 super seedling is selected in the mix pedigree with 1a, 2a, 3a seedling.