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利用Li-6400便携式光合作用测定系统,研究自然条件下不同年龄人工林尾巨桉(2年生、4年生和6年生)叶片光合特性及水分利用效率.结果表明:一年中桉树人工林叶片净光合速率、蒸腾速率和水分利用效率的月动态呈现单峰曲线,以8月份为最高,1月份为最低;从9月到第2年1月逐渐减低,从2月到8月缓慢增加;胞间CO_2浓度的月动态与其相反.不同林龄桉树人工林叶片净光合速率、蒸腾速率和水分利用效率从2013年9月到2014年4月大小顺序为4年>2年>6年,而从2014年5月到8月大小顺序为2年>4年>6年;净光合速率、蒸腾速率和水分利用效率的年平均值大小顺序为2年>4年>6年,2年、4年、6年的年水分利用效率平均值为2.33μmol/mmol、2.28μmol/mmol、2.17μmol/mmol,且净光合速率与胸径增长量呈显著正相关(P<0.05).桉树人工林叶片净光合速率、蒸腾速率和水分利用效率与气孔导度、大气温度、光合有效辐射呈极显著(P<0.01)或显著(P<0.05)正相关,与胞间CO_2浓度呈负相关.随着林龄的增加,净光合速率、蒸腾速率和水分利用效率逐渐降低,因此桉树人工林早期对水分及养分需求大,进行合理地养分管理和定向培育,可实现桉树的可持续经营.
Li-6400 portable photosynthesis system was used to study the leaf photosynthetic characteristics and water use efficiency (Eucalyptus urophylla) of Eucalyptus urophylla under natural conditions at different ages. The results showed that: The monthly dynamic of photosynthetic rate, transpiration rate and water use efficiency showed unimodal curve, which was the highest in August and the lowest in January; it decreased from September to the second year in January and slowly increased from February to August; The monthly dynamic of CO 2 concentration was opposite to that of the control.The net photosynthetic rate, transpiration rate and water use efficiency of Eucalyptus plantations from September 2013 to April 2014 were in the order of 4 years> 2 years> 6 years from From May to August in 2014, the order of magnitude was 2 years> 4 years> 6 years; the annual mean values of net photosynthetic rate, transpiration rate and water use efficiency were in the order of 2 years> 4 years> 6 years, 2 years, 4 years , And the annual average water use efficiency was 2.33μmol / mmol, 2.28μmol / mmol and 2.17μmol / mmol, respectively, and the net photosynthetic rate had a significant positive correlation with the increment of DBH (P <0.05) Rate, transpiration rate and water use efficiency and stomatal conductance, atmospheric temperature, photosynthesis The effective radiation was significantly (P <0.01) or significantly (P <0.05) and negatively correlated with the intercellular CO 2 concentration. With increasing age, net photosynthetic rate, transpiration rate and water use efficiency decreased Eucalyptus plantation early on the water and nutrients demand, the rational management of nutrients and directional cultivation, can achieve the sustainable management of eucalyptus.