北五味子光合日变化特性的研究

用LI-6400型光合测定系统,测定了北五味子Schisandra chinensis Baill叶片光合作用的日变化,结果表明,北五味子叶片净光合速率(Pn)呈双峰型变化.清晨随着日出,Pn随光照强度和温度的增加而增加,在11:00达到高峰,随后下降,到15:00时出现第2个高峰,但峰值比第1个的低.5:00—11:00及15:00—19:00的光合变化与光照强度和温度的变化趋势基本一致,11:00—14:00光合作用随光照强度和温度的增加而下降,出现了明显的光合"午休"现象.相关性分析表明,光合午休与中午高光强、高温和低湿有关.气孔导度(Gs)和蒸腾速率(Tr)也为双峰型曲线,Pn与Gs、Tr呈显著正相关,通过对胞间二氧化碳浓度的分析表明,气孔限制在北五味子叶片的"光合午休"中起了一定作用.

Study on the Characteristics of Diurnal Changes of Photosynthesis in Schisandra chinensis Baill

Diurnal changes of net photosynthetic rate and relative factors in leaves of Schisandra chinensis Baill were measured by using LI-6400 portable photosynthesis system.Diurnal changes of net photosynthetic rate showed double-peak styles.The first maximum peak was measured at 11:00,the second-peak was measured at 15:00.Diurnal changes of net photosynthetic rate were consistent to the variation of light intensity at 5:00-11:00 and 11:00-19:00,respectively,and the photosynthesis had a"midday rest"for the dropping at 11:00-14:00.Stomatal conductance and transpiration rate were showed double-peak styles and the net photosynthetic rate were significantly positively correlated with stomatal conductanceand transpiration rate.Based on the tendency of changes in net photosynthetic rate,stomatal conductance and intercellular CO_2 concentration,the midday deperession in the S.chinensis Baill was speculated to be controlled by stomatal factors.