油页岩废渣地12种木本植物光合作用的季节变化

SEASONAL CHANGES OF PHOTOSYNTHETIC CHARACTERISTICS IN 12 TREE SPECIES INTRODUCED ONTO OIL SHALE WASTE

研究了引种在油页岩工业废渣地12种木本植物冬、夏季光合作用特征,根据此评价引种植物的光合作用效率,测定的主要参数包括净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)。结果表明:1)冬、夏季各项测定指标差异很大,Pn、Tr、Gs均是夏季高于冬季,而且,夏季平均Pn、Tr和Gs值要比冬季均值分别高60.9%、77.7%和85.7%,但水分利用效率(WUE)却是冬季高于夏季26.8%～77.2%。2)Pn日变化节律冬、夏季有异,夏季较多的种出现“双峰型”,而冬季较多出现“单峰型”。但也有例外,樟树(Cinnamomumcamphora)冬、夏季均出现“单峰”;油榄仁(Terminaliabellirica)、红胶木(Tristaniaconferta)和柚木(Tectonagrandis)冬、夏季均出现“双峰”;海南蒲桃(Syzygiumcumini)则冬季为“双峰”,夏季为“单峰”。3)若某一植物种在冬、夏季都表现出有较高的Pn日均值,相对于另一种植物其中有一季有较高的Pn,说明前者更适应当地环境生长。据此,以冬、夏季Pn日均值的平均值高低排序,评价参试植物在当地自然光照条件下的光合作用效率高低,树种的排序为:大叶相思(Acaciaauriculiformis)、油榄仁、铁刀木(Cassiasiamea)、云南石梓(Gmelinaarborea)、柚木、红胶木、樟树、海南红豆(Ormosiapinnata)、铁冬青(Ilexrotunda)、海南蒲桃、双翼豆(Peltophorumptetocarpum)和海南翅萍婆(Pterygotaalata)。

Background and Aims Phytoremediation is an important method for restoring bare soil or slag; however, the physiological traits of plants used for revegetation are poorly known, even though such traits are important to successful remediation. This study was carried out on oil shale waste in Maoming City, Guangdong Province to screen for tree species with high photosynthetic potential, appraise the ability of these plants to acclimatize to oil shale waste, and provide valuable information for ecological restoration of similar waste sites. Methods Diurnal variation of photosynthesis was measured for 12 tree species in summer and winter, using portable photosynthetic equipment （LI-6400, LI-COR, Inc., USA）. Other parameters such as transpiration, stomatal conductance, relative humidity, etc. were measured simultaneously, and water use efficiency （WUE） was calculated as net photosynthesis divided by transpiration. Key Results There were large seasonal differences in all parameters, with values of net photosynthesis, transpiration, and stomatal conductance higher in summer than winter （60.9 %, 77.7 % and 85.7 %, respectively）, but WUE higher in winter than in summer （26.8% -77.2% ）. Diumal variation of net photosynthesis also exhibited seasonal differences. Many tree species exhibited a bimodal peak in summer and a unimodal peak in winter; however, Cinnamomum camphora was unimodal in both seasons; Terminalia beUirica, Tristania confertam, and Tectona grandis were bimodal in both seasons; and Syzygium cumini was bimodal in winter and unimodal in summer. Trees with higher mean net photosynthetic rate in both winter and in summer should be more useful for phytoremediation than species with high net photosynthetic rate in only one season. Accordingly, net photosynthetic rate, which synthesizes all parameters examined, should be considered the most important parameter to appraise the ability of plants to acclimatize. Conclusions According to mean net photosynthetic rates in both winter and summer, the sequence of photosynthesis effciency of the 12 tree species tested was： Acacia auriculiformis, Terminalia bellirica, Cassia siamea , Gmelina arborea , Tectona grandis , Tristania conferta , Cinnamomum camphora , Ormosia pinnata , llex rotunda, Syzygium cumini, Peltophorum ptetocarpum and Pterygota alata.