桤木种源/家系苗期固氮能力的变异及选择

Genetic Variation and Selection of Nitrogen Fixation Ability of Alnus cremastogyne Provenance and Family during the Seedling Stage

对 1年生桤木种源 /家系苗期的根瘤固氮能力进行了研究 ,结果表明桤木苗期的根瘤鲜质量、固氮活性、固氮量种源间和种源内家系间都存在显著或极显著差异。根瘤个数种源间差异不显著 ,种源内家系间差异极显著。根瘤个数、根瘤鲜质量、固氮活性和固氮量的种源遗传力分别为 0 .176 0、0 .9172、0 .1199、0 .1896。揭示出根瘤鲜质量为高度遗传 ,而其它 3个性状属于弱度遗传。根瘤个数、根瘤鲜质量、固氮活性、固氮量 4者相互之间均为极显著正相关 ,揭示了在固氮能力的 4个性状中 ,仅需根据固氮鲜质量这一性状 ,就可评判出综合固氮能力的高低 ,简化了固氮性状选育的内容和过程。苗高、根瘤鲜质量、固氮活性和固氮量与EGA的正相关均达到显著水平 ,呈以经度为主的梯度变异。综合考虑固氮效应及苗木生长量评价的生态环境效应的选择指数 ,认为适宜于生态环境林的优良种源是四川泸定、金堂和邛崃 ,根瘤鲜质量、固氮酶活性、固氮量的遗传增益分别为 5 .14 % ,1.5 6 %和 8.15 %。

Provenance and family variations of nitrogen fixation ability during the seedling stage of Alnus cremastogrne were discussed. The random complete block design was adopted in the test. The result showed that except the number of nodule, there were significant or very significant differences in indexes of nitrogen fixation ability among provenances and single 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 0, 0.917 2, 0.119 9 and 0.189 6, respectively, and it showed that the amount of nodulation was genetically controlled in strong degree. The relationships between growth traits and indexes of nitrogen fixation ability were closely positive correlation, and the correlation coefficient varied from 0.399 9～0.630 2. The correlations between the indexes of nitrogen fixation and EGA were significant. Provenances from Luding and Jintang are better, which have been selected according to the comprehensive index of growth and nitrogen fixation ability, and the genetic gains of amount of nodulation, nitrogenase activity and amount of nitrogen fixation were 5.14%, 1.56% and 8.15%.