罗甸小米核桃苗木光合作用特性

Seedling Photosynthetic Characteristics of Juglans regia L.f.luodianense Liu et Xu

利用Li-6400便携式光合作用测定系统测定罗甸小米核桃苗木叶片光合生理生态特性及环境因子日变化。结果表明,一天中,罗甸小米核桃的气孔导度(Gs)为单峰型曲线,最大值出现在12:00左右;蒸腾速率(Tr)及叶片蒸汽压亏缺(VpdL)为双峰型曲线,二者峰值分别出现在12:00及16:00左右;胞间CO2摩尔分数(Ci)为"W"型曲线,早间、傍晚以及午间较高。罗甸小米核桃净光合速率(Pn)日变化曲线为双峰型,第一峰(峰值为9.56μmol.m-2.s-1)出现在12:00左右,第2峰(峰值为6.71μmol.m-2.s-1)出现于15:00左右,具有明显的光合"午休"现象。相关性分析及回归分析表明,罗甸小米核桃Pn与Gs、光合有效辐射(PAR)及Tr显著正相关,与Ci显著负相关。光合"午休"现象原因主要为环境因子变化引起叶肉细胞光合活性降低的非气孔限制因素。Gs与Ci为影响罗甸小米核桃Pn的主要因子,Gs影响最大、Ci次之。

The seedling eco-physiological photosynthetic characteristics of Juglans regia L.f.luodianense Liu et Xu and the environmental factors were measured using Li-6400 portable photosynthesis system.The results were summarized as follows： the diurnal variation of stomatal conductance（Gs） of J.regia L.f.luodianense showed a single peak curve,and reached the maximum at 12 o＇clock.The diurnal variation curves of leaf transpiration（Tr） and leaf vapor pressure deficit（VpdL） of J.regia L.f.luodianense both were twin-peaked,occurring at 12 o＇clock and 16 o＇clock.The diurnal variation pattern of intercellular CO2 concentration（Ci） showed a ＂W＂-type curve,the values were higher in the morning,late in the afternoon and in the midday.The diurnal change of net photosynthetic rate（Pn） of J.regia L.f.luodianense presented a bimodal pattern,the first peak（Pn=9.56 μmol·m-2·s-1） appeared at 12 o＇clock and the second peak（Pn=6.71 μmol·m^-2·s^-1） appeared at 15 o＇clock,and in midday there was an obvious photosynthetic depression.The correlation analysis and regression analysis showed that the diurnal variations of Pn related significantly and positively to that of Gs,PAR and Tr,but related significantly and negatively to that of Ci.The main reasons of midday photosynthetic depression was non-stomatal limitation factors based on that the photosynthetically active of diachyma cells were reduced by the changes of environmental factors.Gs and Ci were the main factors exerting an influence on Pn of J.regia L.f.luodianense,and Gs produced more influence than Ci.