干旱胁迫对不同种源香椿苗木光合特性的影响

Effects of drought stress on photosynthetic characteristics in Toona sinensis seedlings from different provenances

以南京、广元、洞口、随州、西峡、安康6个种源香椿苗木为材料进行盆栽试验,研究干旱胁迫对香椿光合作用的影响。结果表明:干旱胁迫下6种源香椿叶片的净光合速率(Pn)、气孔导度(Gs)皆有不同幅度的下降,胞间CO2浓度(Ci)的变化规律不一致。随着胁迫的持续进行,Pn下降幅度减小,抗性较弱的洞口种源的下降幅度最大,复水后恢复能力也较弱;不同种源Gs的变化与Pn类似;在两种胁迫水平下,南京、广元、西峡和安康4种源Gs和Ci随着胁迫的加重而降低,其光合能力主要受气孔因素限制;而洞口和随州2种源在胁迫末期Gs继续降低但Ci却升高,光合能力的下降同时受气孔限制和非气孔限制因素的影响,恢复供水其功能也不能很快地恢复。各种源3个主要光合作用参数的动态变化与其抗旱性强弱等级一致。

Effects of drought stress on photosynthesis were studied in potted Toona sinensis seedlings of six provenances, which were from Nanjing, Guangyuan, Dongkou, Suizhou, Xixia and Ankang cities. The results showed that under drought stress, the net photosynthetic rate （Pn） and stomatal conductance （ G0） decreased in leaves of six provenances, while intercellular CO2 concentration （ Ci） showed different trends. With prolonged stress, the decrement of P. fell down. The highest decrement of Pn was observed in Dongkou provenance which had less tolerance to drought stress and recovered less after rewatering. The change of Gs was similar to that of Pn. Under two stress levels, the Gs and Ci decreased with prolonged stress in provenances of Nanjing, Guangyuan, Xixia and Ankang, whose photosynthetic abilities were mainly restricted by stomatal factors. For the provenances of Dongkou and Suizhou, the Gs decreased while the Ci increased during the end period of treatment, whose photosynthetic abilities were mainly restricted by both stomatal and non-stomatal factors ; the plants of these two provenances recovered slowly after rewatering. The dynamic changes of photosynthetic parameters （Pn, Gn and Ci） in six T. sinensis provenances showed the same trend with drought-resistant ability.