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树木光合作用的测定常因植株高大而难以开展,其中离体测定是解决途径之一。但离体测定的方法及其可靠性因树种而异。选取东北东部温带森林中特性各异的7种主要树种:针叶树(红松(Pinus koraiensis)、长白落叶松(Larix olgensis))、散孔材(白桦(Betula platyphylla)、胡桃楸(Juglans mandshurica))和环孔材(水曲柳(Fraxinus mandshurica)、黄榆(Ulmus macro-carpa)、蒙古栎(Quercus mongolica)),首先采用光合速率恢复到光合诱导前稳定值90%的时间(T90)长短和叶片蒸腾速率(E)的大小评估离体叶片水分供应状况及其光合活力,以此确定较优的离体测定方案;同时,观测离体叶片的光合活力稳定时间;最后通过比较原位测定和采用所确定的较优离体方案测定的各树种叶片气体交换参数,论证采用离体测定光合作用的可靠性。结果表明:除蒙古栎外的6个树种的离体叶片均具有较高、较稳定的水分供应和光合活力。离体枝条或复叶插入水中,环剥去除切口处3cm左右的韧皮部和剩余叶片的方法,是这6个温带树种叶片光合能力的较优离体测定方法。6个树种叶片的T90受树木特性的影响而差异显著(p<0.05),其中环孔材树种的T90显著高于散孔材和针叶树种。6个树种离体叶片在1h内均有较高、较稳定的水分供应和光合活力。在此期间离体所测得的绝大多数叶片的气体交换参数与其原位测定值之间的差异不显著。该研究提出了可行的树木叶片光合作用的离体测定方案,适用于蒙古栎以外的其他6个温带树种。
The determination of photosynthesis of trees is often difficult to carry out due to tall plants, of which in vitro determination is one of the solutions. However, in vitro methods and their reliability depend on the species. Seven main species with different characteristics in temperate forests of eastern Northeast China were selected: conifer (Pinus koraiensis, Larix olgensis), Betula platyphylla, Juglans mandshurica And Fraxinus mandshurica (Ulmus macro-carpa) and Quercus mongolica (Phyllostachys meyeri), the photosynthetic rate was first restored to 90% of the time before photosynthesis induction (T90) and The leaf transpiration rate (E) of the size assessment of leaf water supply and photosynthetic activity in vitro leaves, in order to determine the optimal in vitro determination program; the same time, to observe the leaf photosynthetic vitality stability time; and finally by comparing the in situ determination and The gas exchange parameters of the leaves of each species determined by the optimized in vitro program were used to demonstrate the reliability of photosynthesis measured in vitro. The results showed that the leaves of six species except Quercus mongolica had high and stable water supply and photosynthetic activity. In vitro branches or compound leaves were inserted into water, and the method of removing the phloem and the remaining leaves about 3 cm at the incision was the best in vitro determination method for the photosynthetic capacity of the leaves of the six temperate species. The T90 of six species of leaves was significantly different (p <0.05) from the characteristics of trees, and the T90 of ring-shaped species was significantly higher than those of spodoptera and conifer. Six species of isolated leaves in 1h have higher, more stable water supply and photosynthetic activity. There was no significant difference between the gas exchange parameters measured in vitro for the vast majority of leaves in vitro and their in situ measurements. This study proposed a feasible in vitro determination of photosynthesis of tree leaves for 6 temperate species other than Quercus mongolica.