不同季节小蓬竹光合特性日变化及其与环境因子的关系

Relationship between diurnal changes of photosynthetic characteristics and environmental factors of Drepanostachyum luodianense in different seasons

通过研究不同季节小蓬竹净光合速率日变化及生理生态因子的相互关系,明确不同季节的外界环境下其光合作用的主导生理生态因子。以春季(4月)、夏季(7月)、秋季(9月)、冬季(1月)的小蓬竹为材料,采用Li-6400便携式光合分析仪测定净光合速率和环境因子,并运用相关分析与通径分析方法,对其净光合速率与生理生态因子间的的相互性进行分析。结果表明:(1)4月、7月以及9月净光合速率日变化(Pn)呈双峰曲线,具有明显的光合"午休"过程;1月呈单峰曲线,无光合"午休"过程。(2)不同月份小蓬竹叶片温度(TL)、光合有效辐射(PAR)日变化均呈现先增加后降低趋势,气孔导度(Gs)的日变化与Pn日变化相似,呈现双峰型变化;(3)小蓬竹在春、冬两季内,PAR均是决策变量,TL均是限制变量;夏、秋两季决策变量则是Gs,限制变量为叶片蒸汽压亏缺(Vpd L)和胞间CO2浓度(Ci)。研究表明,4月份小蓬竹Pn下降主要是由于非气孔限制引起,7月份主要是由气孔限制所致,而9月份则由气孔限制与非气孔限制交替进行造成。不同季节影响小蓬竹Pn日变化的主要生理生态因子不尽相同,其中,主要生态因子是PAR、TL和Vpd L,主要生理因子是Gs和Ci。

By studying the diurnal variation of net photosynthetic rate and the relationship between physiological and ecological factors in different seasons, the dominant physiological and ecological factors of photosynthesis in different seasons were determined. Drepanostachyum luodianense was used in spring(April), summer(July), autumn(September) and winter(January), net photosynthetic rate and environmental and physiological factors of Drepanostachyum luodianense were measured by Li-6400 portable photosynthesis system. Mutuality of net photosynthetic rate and environmental and physiological factors were analyzed with correlation analysis and path analysis. The result indicated that:(1) P_n in April, July, September exhibits an asymmetric dual-peak curve, the curve has an obvious midday depression. Conversely, Pn in January appeared as single peak curve, does not appear midday depression.(2) The diurnal variation curves of TL and PAR in different months exhibited a trend of firstly increase and then decrease.(3) In spring and winter, the decision variable was PAR and the limiting variable was TL. The decision variable in summer and autumn was G_s, and the limiting variables were VpdL and C_i. These analyses indicated that the midday depression of Drepanostachyum luodianense in April was mainly regulated by non-stomatal limitation factor, but in July was mainly regulated by stomatal limitation factor, and in September was caused by alternating stomatal and non-stomatal limitation factor. The main reasons affecting Pn of Drepanostachyum luodianense were various, among them, the main ecological factors are PAR, TL and VpdL, the main physiological factors are G_s and C_i.