光皮树不同无性系果期光合日变化研究

摘要

In order to explore the diurnal variation of photosynthetic characteristics of Cornus wilsoniana clones,the diurnal variation of photosynthesis of 8 Cornus wilsoniana clones were measured in friuting season and analyzed using an Li-6400 portable photosynthetic analyzer.The results showed as follows:(1) The diurnal variation of net photosynthetic rate (Pn) and stomatal conductance(G,) of all tested clones showed single-peak curve,and the peak of most clones is at 9:00 am.The diurnal variation of transpiration rate (Tr) revealed double-peak curve,except JX13 and GY8040,and the first peak is higher than the second.The diurnal variation of intercellular concentration (Ci) appeared tabular W-type.The diurnal variation of water use efficiency (WUE) showed V-shape curve,and the minimum values is at about 15:00 pm.(2) The daily average values ofPn,Tn Gs,Ci,WUE of 8 Cornus wilsoniana Clones had not significant difference,respectively.The Pn of GY8040,JX3,LC7,JX6 are higher than others,over 10.0 μmol·m-2s-1.(3) In the effect of environment factors,PAR directly influence the photosynthesis physiological characteristics or indirectly by Ta and RH-,Ca showed remarkable positive correlation with Ci· Pn had very significant positive correlation with Gs and Tn The importance of factors effect on Pn was Gs ＞ Tr ＞ PAR ＞ RH ＞ Ta＞WUE＞Ci＞Ca.%为研究光皮树光合特征的日变异规律,采用美国Li-6400便携式光合测定仪,对光皮树8个无性系8月份果期叶片的光合日变化进行了测定和分析,结果表明:(1)参试光皮树无性系净光合速率(Pn)、气孔导度(Gs)日变化均呈单峰曲线,多数无性系最大值出现在9:00左右;蒸腾速率(Tr)日变化除JX13和GY8040外,均呈双峰曲线,第一个峰值高于第二个峰值;胞间CO2浓度(Ci)曰变化曲线为扁平的“W”形;水分利用效率(WUE)日变化为不规则“V”形,谷底在15:00左右.(2)8个光皮树无性系净光合速率、蒸腾速率、气孔导度、胞间CO2浓度、水分利用效率日均值间差异不显著,其中GY8040、JX3、LC7、JX6的净光合速率(Pn)较高,均达到10.0 μmol·m2s-1以上.(3)环境因子中,光照强度(PPAR)直接或通过大气温度(La)、大气湿度(HR)影响植物光合生理,大气CO2浓度(Ca)仅与胞间CO2浓度(Ci)呈显著正相关.净光合速率(Pn)与气孔导度(sG)和蒸腾速率(Tr)呈极显著正相关,各因素对光皮树净光合速率(Pn)影响从大到小依次为气孔导度＞蒸腾速率＞光照强度＞大气湿度＞大气温度＞水分利用效率＞胞间CO2浓度＞大气CO2浓度.