刺槐光合生理生态特性日变化研究

Studies on Eco-Physiological Characteristics of Photosynthetic of Diurnal Variation of Robinia pseudoacacia

为了解刺槐光合生理生态特性及生长的适宜生态条件,培育出优质高产的林木,采用LI-6400光合测定系统对刺槐的光合生理特性日变化及其与气象因子关系进行了研究。结果表:(1)刺槐的Pn日变化呈"双峰型"曲线,有明显的"午休"现象,第一个峰出现在9:00左右,第二个峰出现在15:00左右,第一个峰值明显高于第二个峰值。(2)Tr在很大程度上决定于气孔的活动状态,Ci因为Gs的降低而减少,刺槐的光合速率控制因子为气孔限制。(3)Pn与Gs成极显著正相关,与Tr成显著性正相关。环境因子主要是影响叶片的Tr、Vpdl和Tl来影响Pn,PAR对Pn的影响较大,但可能不是导致刺槐光合"午休"的直接因素。

In order to understand the eco-physiological characteristics and its suitable ecological condition of Robinia pseudoacacia to develop high-quality and high-yield forest, the studies on diurnal change of photosynthetic characteristics of Robinia pseudoacacia and its environmental factors were conducted by the Li-6400 portable photosynthetic system. The results showed as following： （1） The diurnal change of net photosynthetic rate （Pn） presented a double-peak curve, and showed obvious midday depression, the first peak value occurred at 9：00 and the second one at 15：00, and the value of the first peak was significantly higher than the seconds＇. （2） The transpiration rate （Tr） was mainly determined by the stomatal status, intercellular COz concentration （Ci） decrease with the lowing of stomatal conductance （Gs）. So the controlling factor of photosynthetic rate was stomatal limitation. （3） The Pn and Gs was a very significant positive correlation, and Pn and Tr was a significant positive correlation, the environmental factors affected the Pn mainly by Tr, leaf water deficit （Vpdl） and leaf temperature affected by photosynthetic active radiation （PAR）, However, it wasn＇t （T1）. The variation of Pn was greatly the direct factors which lead to the midday depression.