Study On Genetic Variation And Selection Of Alnus Cremastogyne

Provenance trials of Alnus cremastogyne were planted at 6 sites located at the middle and lower reaches of Yangtse River with 15 provenance at each test. Provenance and family variation of growth, adaptation and genetic stability were analyzed. Wood density , fiber length and dry trunk weight were analyzed on the basis of 462 wood samples from three sites of the plantations with 5 provenances at age 6. The provenance variation of phenotypic diversity for fruit and seed was discussed. Provenance and family variation of nitrogen fixation ability during seedling stage of alder were also discussed. The major results were as follows.1.There was significant difference among provenances in height (B, diameter of breast height (DBH)and volume(V), and the interaction between provenance and environment was also very significant. The genetic stabilityand adaptability of provenances have been evaluated using Eberhart's traitregression parameters (b_i and s_di²), Wrick's ecovalue parameter (W_i), additivemain effects and multiplicative interaction analysis (AMMI). The estimates of AMMI were greatly concordant with the estimates of ecovalue. On the basis of age-age correlation analysis , the correlation between 6 years and 14 years (r=0. 7580) in heights was statistically significant, and it showed that early selection for heights was reliable. The provenance heritabilities and standard errors of H, DBH and V were 0. 8738 ±0. 0482 ,0. 7961 ±0. 0718 and 0.7929± 0. 0727, respectively.2. The means of wood density for provenance was 0. 3823 g/cm³, fiber length was 1.2479mm and dry trunk weight was 6.1511kg. There were significantdifferences among provenances in wood density and fiber length. The interaction between provenance and site in wood density was not statistically significant, but the interaction between provenance and site in fiber length was significant. There was significant difference among provenances and families in dry trunk weight, meanwhile, The interaction between provenance and site, family and site in dry trunk weight were statistically significant. Genetic parameter analysis showed that provenance heritability and family heritability of wood density, fiber length, dry trunk weight were 0.5648-0.6618, 0.2857-0.6535, 0.2553-0.7895, 0.2905-0.4528, 0.2741-0.7524, 0.1677-0.8307, respectively, and showed that wood traits of alder were genetically controlled in moderate to strong degree, so it was feasible to improve the wood quality of Alnus cremastogyne. The mathematical models for property parameters on growth-ring wood density and fiber length in the radial direction were set up. The analysis of age-age correlation showed the juvenile-mature correlation was significant. The age of early selection for Alnus cremastogyne in wood quality was determinated at about age 6. It was also suggested that the early selection of wood density should be carried out during 10-11 years. Wood density and fiber length were not significantly interrelated with each other. The coefficient of correlation between wood quality and growth characteristics was not high, so independent selection of wood or growth can be used. Dry trunk weight was the most suitable index to show production efficiency of alder pulp wood plantation. The direct path coefficient of volume was highest (0.79) to Dry trunk weight. The next was height (0.40) and wood density (0.26). Tree height, DBH and crown range had effects on dry trunk weight indirectly.3. Except the number of nodule, there was significant or very significant differences for index of nitrogen fixation ability among provenances andsingle trees within provenances during the seedling stage of the alder. The heritabilities of the number of nodule , amount of nodulation, nitrogenase activity and amount of nitrogen fixation were 0. 176(hO. 9172>0. 1199 and 0. 1896, respectively, and it showed the amount of nodulation was genetically Controlled in stiong degree. The relationship between grovJi traits and index of nitrogen fixation ability was closely positive correlation, and the correlation coefficient varied from 0.3999-0. 6302.4. There was significant difference among provenances and trees within provenances in fruit width , fruit length/ fruit width and fruit lengthX fruit width. Significant difference for thousand seed weight was also existed among provenances. The repeatabilities of the peduncle length, fruit length, fruit width, fruit length/ fruit width, the peduncle length/fruit length, fruit lengthXfruit width and thousand seed weight were 0. 3278> 0. 3404> 0.9411, 0. 898U 0. 2637? 0. 8984 and 0. 8071, respectively. The diversity for peduncle length and peduncle length/fruit length in Luding provenances was richest. The diversity for fruit length, fruit width, fruit length/ fruit width, fruit lengthXfruit width in Jiange and Gongxian provenances was richer.5. The relationship between growth and latitude ^ altitude > EGA (ecological gradient axis) was significant negative correlation. The fiber length and dry trunk weight was not related to the longitude and latitude, however, the wood density was clearly positive related to the latitude. It showed that there was a increasing tread in wood density of provenances from the west to the east of the range. The correlation between the index of nitrogen fixation and EGA was significant.6. According to EGA and average value for traits (growth, wood quality, nitrogen fixation ability and morphology of pseudo-strobile) of provenances,the distribution area of long-peduncled alder could be divided into 3 zones,(l)District of Northwest Sichuan, (2) District of Central Sichuan , (3) District of South Sichuan. The Best five provenances, which are Yanjing of Jintang , huaikou of Jintang, muchuan, Qionglai and Yanting, have been selected on the basis of combined index of growth and wood properties. Luding and Jintang were better provenances which have been selected according to comprehensive index of growth and nitrogen fixation ability. Based on the main effective values and stability parameters, this paper suggested the suitable plantation regions for the provenances and fine provenances for plantation regions.