光皮树不同无性系果期光合日变化研究

Research on diurnal variation of photosynthetic characteristics of Cornus wilsoniana clones during friuting season

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CO_2浓度(C_i)日变化曲线为扁平的"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CO_2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(P_n)较高,均达到10.0μmol·m^(-2)s^(-1)以上。(3)环境因子中,光照强度(PPAR)直接或通过大气温度(T_a)、大气湿度(HR)影响植物光合生理,大气CO_2浓度(Ca)仅与胞间CO_2浓度(C_i)呈显著正相关。净光合速率(P_n)与气孔导度(G_s)和蒸腾速率(T_r)呈极显著正相关,各因素对光皮树净光合速率(P_n)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CO_2浓度>大气CO_2浓度。

In order to explore the diurnal variation of photosynthetic characteristics of Comus wilsoniana clones, the diurnal variation of photosynthesis of 8 Comus 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（G1） 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 GYS040, 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 of Pn, Ti, G8, Ci, WUE of 8 Comus 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 Ca. Pn had very significant positive correlation with Gs and T, The importance of factors effect on Pn was Gs 〉 Tr 〉 PAR 〉 RH 〉 Tn 〉 WUE 〉 Ci 〉 Ca.