高温与加富CO_2耦合条件下温室黄瓜叶片衰老及SOD、POD活性研究

Leaf senescence and SOD and POD activities of cucumber in greenhouse under coupled high temperature and elevated CO_2

【目的】研究高温与加富不同浓度CO_2耦合条件下黄瓜叶片的光合作用及SOD、POD活性等指标的变化,探究高温与加富CO_2耦合条件下叶片衰老机理及净光合速率(Pn)形成的内部生理机制。【方法】以温室嫁接黄瓜为试材,通过设置对照、单纯高温处理、高温加富低浓度(500~900 mol/L)CO_2、高温加富中浓度(900~1 200mol/L)CO_2和高温加富高浓度(1 200~1 600mol/L)CO_25个处理,测定叶片Pn、叶绿素、淀粉、可溶性糖和丙二醛(MDA)含量及SOD、POD活性,比较各处理上述指标的变化,并分析Pn与其他指标的相关性。【结果】随着黄瓜生育进程的推移,不同处理和对照的叶片的Pn、叶绿素、可溶性糖含量及SOD、POD活性均呈先升高后降低的趋势,淀粉和MDA含量均呈先下降后上升的趋势。试验前期(21d之前),3个高温加富CO_2处理中,随着CO_2浓度的升高,黄瓜叶片Pn、叶绿素及可溶性糖含量呈逐渐上升趋势,其中高浓度和中浓度CO_2处理的Pn显著高于对照及单纯高温处理。高温+高浓度CO_2处理的叶片淀粉含量在试验期间始终显著高于其他处理,在试验后期(28d之后)显著上升;单纯高温处理的MDA含量始终高于其他处理。相关分析表明,高温+高浓度CO_2处理的叶片Pn与淀粉及MDA含量均呈显著负相关,单纯高温处理的Pn与MDA含量呈显著负相关。【结论】高温与加富CO_2耦合能够增强黄瓜光合作用,缓解高温伤害;高温加富高浓度(1 200~1 600mol/L)CO_2处理在生育后期会由于淀粉及MDA积累而加速植株老化,故随着生育期的推进,应降低CO_2施用浓度。

【Objective】The photosynthetic rate and superoxideradical（SOD）and peroxidase（POD）activities of cucumber leaves under high temperature and elevated CO_2 were analyzed to investigate the metabolism of leaf senescence and internal physiological mechanism of photosynthesis.【Method】Net photosynthetic rate,contents of chlorophyll,starch,carbohydrate and malonaldehyde（MDA）,and activities of SOD and POD of grafting cucumber leaves were measured and analyzed under 5 different treatments inclu-ding control,high temperature,high temperature and low CO_2（500-900 mol/L）,high temperature and medium CO_2（900-1 200mol/L）,and high temperature and high CO_2（1 200-1 600mol/L）.【Result】Net photosynthetic rate,contents of chlorophyll and carbohydrate and activities of SOD and POD firstly increased followed by decrease,while contents of starch and MDA firstly decreased followed by increase under different treatments.In the early growth stage（first 21d）,photosynthetic rate,and contents of chlorophyll and carbohydrate of cucumber leaf increased significantly with the increase of CO_2 concentration.Starch content of high temperature and high CO_2 treatment was the highest among all the treatments in the whole growing period,and there was a significant increase in the later stage（after 28d）.The content of MDA of high temperature treatment was higher than other treatments all the time.The net photosynthetic rate under high temperature and high CO_2 treatment had a significant positive correlation with contents of starch and MDA,while the net photosynthetic rate of high temperature treatment had a significantly positive correlation with MDA content.【Conclusion】Temperature increase and elevated CO_2 helped to increase photosynthesis and decrease high temperature damage.The accumulation of starch and MDA would accelerate aging in the later growth stage under high temperature and high CO_2（1 200-1 600 mol/L）treatment,so with the growth time extending,the concentration of CO_2 should be reduced.