摘要
紫茎泽兰是一种外来入侵有害植物,从CO2交换特性角度研究其入侵特性的报道较少.对其生殖器官(花和果)和营养器官(茎杆和根系和不同生长条件下的叶片)气体交换特性进行了测定,并与8种本地种和已报到的世界主要草本和木本植物的光合速率、呼吸速率进行了对比.在结果中观察到,不同叶片的净光合能力和呼吸速率差异较大,同一茎杆不同叶片、不同年龄株丛和同一株丛不同年龄分株上叶片、不同生境内嫩叶、成叶和老叶、不同长度节间上生长叶片以及基生叶和顶生叶光合能力都受到气孔限制和非气孔限制(羧化能力)的影响,但不同叶片所受的限制程度不同.综合来看,最大叶片净光合速率为17.6 μmol·m-2s-1,分布最集中的区域为11～15μmol·m-2s-1,占所有观测值的50%,而叶片暗呼吸速率70%以上的观测结果在1～3μmol·m-2s-1之间,分布最集中的区域在1.5～2.0μmol·m-2s-1,占所有测定值的40%.生殖器官具有较高的代谢机能,其中幼嫩花蕾的呼吸速率高达37μmol·kg-1 DW s-1,其呼吸速率平均比茎杆和根系高出4倍.而且,花蕾、成花和幼果都具有较高的光合能力(毛光合速率分别约为40,16μmol·kg-1 DW s-1和11μmol·kg-1 DW s-1,是对应呼吸速率的110%,68%和74%),对照同一时期(早春:旱季生殖生长季)的叶片光合能力仅为营养生长季节(夏季)的1/3,生殖器官这种光合作用是对叶片光合能力不足的一种补充.茎杆和根系呼吸速率与直径的关系相似,即直径越小,呼吸速率越高.直径小于0.5mm的根系和茎杆的呼吸速率都在11 μmol·kg-1 DW s-1以上.与其他植物比较,在温度和根系大小相当的情况下,紫茎泽兰与其它根系呼吸比较并没有明显区别.与已报道的草本植物和木本植物光合呼吸范围来看,紫茎泽兰叶片光合速率介于草本植物系统的中等偏下,位于木本植物系统的中等偏上,而其呼吸速率和草本植物相当但明显高于木本植物.与本地其他伴生植物比较,紫茎泽兰光合能力与本地常绿阔叶树种、落叶阔叶树种相当,而明显高于常绿针叶树种,但与同一时期的草本植物光合能力相当甚至偏低.其呼吸速率与本地草本和木本植物相差不明显.因此,不同生境下和不同生长状态的紫茎泽兰的光合和呼吸速率都具有较强的可塑性,这种可塑性可能有利于其定居不同的生境,即在适宜生境保持最高的光合能力和呼吸代谢水平,利于快速入侵,而在胁迫生境下以避免消亡为主,待机爆发.但是,仅通过比较紫茎泽兰与其它植物的叶片光合速率和呼吸速率不容易判断这一植物的强入侵能力.
Eupatorium adenophorum is a famous invasive and alien species and few studies have clarified its invasive ability via study on the gas exchanges characteristics. The gas exchange characteristics of reproductive organs （flower and fruit） and vegetative organs （stem, root, and leaf）of E. adenophorurn Spreng. were discussed in this study in comparison with 8 local species and reported herbaceous and woody plant groups around the world. A wide range of photosynthetic and respiration rates was observed in leaves of this weed grown in different habitats and with different growth status. Even in leaves from the same stem, a 6-fold difference in photosynthesis was observed. Difference in stomatal conductance （gs） and carboxylation efficiency （CE） were responsible for most of these differences, but this responsibility was different for different leaves. The net photosynthetic capacity （Pn） of this weed was peak around 17.6μmol · m^-2s^-1, and the peak of distribution of Pn was 11 -15/μmol· m^-2s^-1 accounting for 50% of total data. Most leaf respiration data （〉70%） were within the range of 1-3μmol· m^-2s^-1 , with 40% within the range of 1.5-2.0μmol·m^-2s^-1. Reproductive organs of this weed had a rather high respiration rate, i.e. flower bud could respire up to 37μmol·kg^-1 DW s^-1, which was 4 times higher than those of stem and root respiration. The gross photosynthetic capacity of flower bud, flower and young fruit was up to 40, 16 and 11μmol·kg^-1 DW s^-1（110%, 68% and 74% of their respiration rate）, respectively. Since leaf Pn in the same period of reproductive season was only one third of that in vegetative season of summer （which means that leaf can supply relative limit photosynthates for seed production in this period of time）, this high photosynthetic capacity in reproductive organs （flowers and fruits） contribute to the formation of seeds. The same decreasing tendency of stem and root respiration with diameter size was found. The root and stem respiration was over 11 μmol· kg^-1 DW s^-1 for those with a diameter smaller than 0.5 mm. No remarkable differences were found between root respiration rates of this weed and three reported other species at similar temperature with similar root size. Moreover, respiration of leaves was similar to other species in the same region and the reviewed data of herbaceous species around the world, but higher than the reviewed data of woody plants. Leaf P. of this weed was slightly lower than to some herbaceous species but rather similar to deciduous and evergreen broadleaved trees in the local region. Comparing with plant groups around the world, leaf Pn of this weed was respectively around lower-middle level and upper-middle level in the reported Pn of herbaceous species and woody species. E. adenophorum had a large variability in photosynthesis and respiration when grown in different habitats and at different stages of growth, which might be beneficial for its flourish at suitable sites and survival at stressed sites. However, it is still difficult to find the underlying reason for the strong invasive potential by inter-specific comparison of the P. and respiration rate alone.
出处
《生态学报》
CAS
CSCD
北大核心
2005年第8期1898-1907,共10页
Acta Ecologica Sinica
基金
教育部重点资助项目(No.104191)
国家林业局<中国野生植物保护行动计划>资助项目
林业有害植物专项调查资助项目~~
关键词
紫茎泽兰
光合作用
呼吸作用
营养器官
生殖器官
种间比较
Eupatoriurn adenophorurn
photosynthesis
respiration
vegetative organs
reproductive organs
inter-specific comparison
