南亚热带四种不同演化程度禾本科植物夏季光能利用策略差异分析

Analysis on the differences of light utilization strategies of four Poaceae species with different evolution degrees in the south subtropical region of China during summer period

关键词:  光合演化, 光适应, 禾本科植物, 高温, 南亚热带

Key words:  evolution of photosynthesis, photosynthetic adaptation, Poaceae species, hot stress, south subtropical

摘要:

为了探究甘蔗、地毯草、芦苇、佛肚竹这四种禾本科植物的光能利用策略,该文以大田或原生境植株为材料,于炎夏伏天最热时节活体监测其叶绿素荧光和光合气体交换特性,并分析其色素含量。结果表明:(1)C₄甘蔗和C₄地毯草具有高净光合速率(P_n),是消耗利用光能的主要手段,并且高P_n和高水分利用效率(WUE)、高量子效率(Φ_i)耦合在一起;(2)C₃芦苇也具有较高的P_n、WUE和Φ_i,其较高的类胡萝卜素与非光化学淬灭热耗散(NPQ)相结合消耗多余光能;(3)C₃佛肚竹P_n、WUE和Φ_i值均最低,但具有最大的叶黄素库容和较高的叶黄素循环转换效率(DPS),通过叶黄素循环和NPQ的偶联消耗多余光能。此外,四种植物光能利用策略也与其生活型有密切关联。该研究结果对甘蔗、地毯草和佛肚竹培育具有重要的现实参考价值,对芦苇生境生态修复和生态规划有科学指导价值。

Abstract:

In order to explore the light energy utilization strategy of four Poaceae species, including sugarcane, carpet grass, bulrush and buddha bamboo, the plants in the field or original habitat were used as materials. We determined the chlorophyll fluorescence and photosynthetic gas exchange characteristics from fresh seedlings leaves in vivo, and analyzed the pigment contents during the hottest period of the summer. The results were as follows:(1)The C₄ sugarcane and carpet grass had high net photosynthetic rate(P_n)coupled with high water use efficiency(WUE)and high quantum yield efficiency(Φ_i), thus being able to assimilate a large fraction of light energy;(2)The C₃ bulrush had relatively high P_n, WUE and Φ_i, and its high carotenoid pool which coupled high nonphotochemical quenching heat dissipation(NPQ)might help the bulrush to get rid of the excessive light energy;(3)The C₃ buddha bamboo had the lowest P_n, WUE and Φ_i, however, its large carotenoid contents and high xanthophyll de-epoxidation level(DPS), coupled with high NPQ were expected to help the leaves to dissipate the excess light energy. In addition, the light-use strategies of the four species were also affected by their life forms. These findings are expected to help breeding programs for sugarcane, carpet grass and buddha bamboo, and to provide a physiological reference for wetland ecological restoration and planning of bulrush.