小叶榕气生根气体交换特征及影响因子研究

用LI-6400XT便携式光合仪测定了小叶榕(Ficus microcarpa L. f.)气生根的气体交换特征。结果表明气生根具有呼吸、蒸腾作用和空气吸湿作用。影响气生根呼吸作用的因素为年龄>空气温度>光强>相对湿度；影响蒸腾作用的因素为年龄>相对湿度>空气温度>光照。年龄小的气生根的呼吸和蒸腾作用较强，年龄大的尤其是木质化程度较高的气生根的呼吸作用较小，水分的释放(蒸腾作用)转变为水分的吸收(吸湿作用)。年龄小的气生根的CO2交换率与温度呈线性关系，温度越高，CO2交换率越大，呼吸越强；H2O交换率与相对湿度呈线性关系，相对湿度越大，H2O交换率越小，蒸腾越弱；年龄大的成熟气生根的H2O交换率与空气相对湿度呈线性关系，相对湿度越大，H2O交换率越小，蒸腾越小。

Gas Exchange Characteristics of Aerial Root and Affecting Factors of Ficus microcarpa L. f.

The gas exchange characteristics of aerial roots of Ficus microcarpa L. f. were measured by using LI-6400XT portable photosynthesis system. The results showed that the aerial roots had obvious respiration and transpiration function. The effect factors on respiration were in order of root age > air temperature >light intensity > relative humidity by orthogonal experiment, and root age > relative humidity > air temperature > light intensity for transpiration. The young aerial root had higher respiration and transpiration rates than the old roots, which highly lignified old aerial roots had low respiratory rate, their transpiration turned to absorption of moisture from air. On the basis of single-factor-analysis, the CO2 exchange rate and H2O exchange rate of young aerial root had linear relationship with temperature and relative humidity, respectively. The higher of temperature, the higher of the CO2 exchange rate, the the stronger of the respiration, the higher of relative humidity, the smaller of the H2O exchange rate, the lower of transpiration. The H2O exchange rate of old mature aerial root had linear relationship with air relative humidity, the higher of relative humidity, the smaller of the H2O exchange rate, the lower of transpiration.