长白落叶松、日本落叶松和兴安落叶松幼苗光合作用特性比较研究

研究长白落叶松(Larix olgensis Herry.)，日本落叶松(Larix kaempferi Carr.) 和兴安落叶松(Larix gmelinii Rupr.)当年生和一年生幼苗的光合作用日变化、季节变化和光响应曲线，结果表明：①三种植物中，长白落叶松、日本落叶松当年生和一年生幼苗和兴安落叶松当年生幼苗光合速率日变化都呈双峰曲线，具有明显的“午休”特征。兴安落叶松一年生幼苗的光合速率日变化呈单峰曲线。②日本落叶松的光饱和点 (LSP) 最高，兴安落叶松光补偿点（LCP）最低。③三种落叶松的一年生幼苗都是在生长中期表现出最大的光合能力。从年龄来看，落叶松当年生幼苗在生长初期和生长中期的光合能力要低于一年生幼苗，但在生长后期高于一年生幼苗。④从种来看，生长初期，当年生和一年生幼苗的最大净光合速率(P_max)均为日本落叶松＞兴安落叶松＞长白落叶松；生长中期，当年生幼苗的P_max规律与生长初期相似，一年生幼苗的P_max为长白落叶松＞日本落叶松＞兴安落叶松；生长后期，当年生幼苗的P_max为长白落叶松＞兴安落叶松＞日本落叶松，一年生幼苗的P_max与生长中期一年生幼苗的规律正好相反。通过分析我们得到结论：三个树种在生长季节相同阶段具有不同的光合特性；每个种不同年龄和生长季节不同阶段也表现出不同的光合特性；三个树种中，长白落叶松幼苗对光抑制引起的光合器官损伤的修复能力最强，日本落叶松次之，兴安落叶松最弱；日本落叶松幼苗较喜光，光合作用能力较强，不易发生光抑制，而兴安落叶松幼苗较耐阴。因此在育苗和造林时应考虑不同树种的光合特性调节最佳的光照条件。

The Studies of the Photosynthetic Characteristics of Larix olgensis Herry.,Larix kaempferi Carr. and Larix gmelinii Rupr. Seedlings

Responses of photosynthetic parameters of current and 1-year-old Larix olgensis Herry., Larix kaempferi Carr. and Larix gmelinii Rupr. seedlings to light intensity,curves of diurnal variation and seasonal variation were studied,the results are as follows: ①Among the three plants,the diurnal variation of photosynthetic rate of current and 1-year-old Larix olgensis Herry. and Larix kaempferi Carr. seedlings and current Larix gmelinii Rupr. seedlings were found as a double-peak curve,which were featured with “Noon rest” but that of 1-year-old Larix gmelinii Rupr. seedlings presented a single peak curve. ②Larix kaempferi Carr. seedlings had the highest light saturation point (LSP) and Larix gmelinii Rupr. seedlings had the lowest light compensation point (LCP). ③All of the 1-year-old Larix seedlings appeared highest photosynthetic capacity in the middle growing stage. From the age,the photosynthetic capacity of current Larix seedlings were lower than that of 1-year-old seedlings in the first and middle growing stages,but higher in the late growing stage. ④From the species,the sequence of maximum net photosynthetic rate (P_max) of current and 1-year-old Larix seedlings was Larix kaempferi Carr.＞Larix gmelinii Rupr.＞Larix olgensis Herry. in the first growing stage; by the middle growing stage,the sequence of P_max of current Larix seedlings was the same to the first growing stage,but 1-year-old Larix seedlings were different as Larix olgensis Herry.＞Larix kaempferi Carr.＞Larix gmelinii Rupr.; turn to the late growing stage,the sequence of P_max of current Larix seedlings was Larix olgensis Herry.＞Larix gmelinii Rupr.＞Larix kaempferi Carr. and that of 1-year-old seedlings was in reverse with those in middle growing stage. We conclude that,there were different photosynthetic characteristics of the three species in the same growing stage; while the different photosynthetic characteristics of same species had also been showed in different ages and growing stages; among the three Larix species,the repair ability to the photoinhibition of Larix olgensis Herry. seedlings were strongest,that of Larix kaempferi Carr. seedlings took second place and Larix gmelinii Rupr. seedlings were weakest. Larix kaempferi Carr. seedlings were more photophilic and had strong photosynthetic capacity, which were not prone to photoinhibition,while Larix gmelinii Rupr. seedlings were more shade-tolerant. Therefore,we should consider the photosynthetic characteristics of different species to obtain optimal illumination conditions in cultivation and forestation.