麻楝生长和光合作用参数种源变异分析

Analysis of Genetic Variation of Photosynthetic Parameters in Different Provenances of Chukrasia tabularis

为系统揭示麻楝种源间生长及光合作用的变异程度和变异规律．以7个国家22个地理种源麻楝2．5年生造林幼树为材料，利用LI一6400光合作用仪于秋季初期对麻楝的光台特征进行测定与分析。结果表明：麻楝的光饱和点为1000μmol／（m2·s）；在同一生境条件麻楝种源间生长差异显著；在生长速率方面，泰国TH2的高生长速率和直径生长速率均显著大于其他种源；平均净光合速率为15．55μmol／（m2·s），变幅为7．5-24．1μmol／（m2·s），CN1最大，VN3最小；平均气孔导度为0．25H2O／（m2．s），变幅为0．13～0.36H2O／（m2．s）．TH2最大．VN3最小；胞间CO2浓度的平均值为228．72μmol／mol，变幅为177．2～294．9μmol／mol，VN3胞间CO2浓度最高．CN1最低；蒸腾速率的平均值为5．25molH2O／（m2．s），变幅为2．1～8．6molH2O／（m2·s），MM1蒸腾速率显著大于其他种源，而VN3蒸腾速率最弱；TH4WUE最高达到6．96μmol/mol，LK1最小仅为2．11μmol/mol。根据不同种源麻楝生长和光合参数的主成分聚类分析，可将22个麻楝种源分为3个集群．其中第1集群长势较好。

Variation in growth and photosynthesis was assessed in 2.5-year-old C. tabularis seedlings from 22 provenances from 7 countries（China, Laos, Malaysia, Myanmar, Sri Lanka, Thailand, Vietnam）. The results showed that the light saturation point was 1 000 μmol/（ ms ·s）. There were significantly differences in growth and photosynthetic indicators of C. tabularis under the same growth environment. According to the principal components analysis and cluster analysis, the 22 provenances were divided into 3 clusters. The first cluster consisted of three fast-growing Chinese provenances（CN1, CN2 and CN）; the net photosynthetic rate and transpiration rate were higher. The second cluster included 10 provenances from Laos（LA3）, Malaysia（MY）, Myanmar（MM3）, Thailand （TH8, TH1, TH2, TH3, TH5, TH6） and Vietnam（VN2）. The third cluster Laos（LAl, LA2）, Myanmar（MMl, MM4）, Sri Lanka（LK1, LK2, LK3）, Thailand（TH4）, and Vietnam（VN3） was characterized by slow growth, and low net photosynthetic rate and transpiration rates.