杨树无性系光合特征的研究

对新培育的金科系列的4个杨树无性系（3^#、6^#、8^#、9^#）的光合特征及净光合速率、水分利用效率与主要影响因子的关系进行了研究。结果表明：不同月份4个无性系的净光合速率的日进程一般在10:00左右达到峰值，然后逐渐降低；蒸腾速率日进程不尽一致；气孔导度在7:00～9:00出现峰值后，缓慢下降。在6～8月，4个无性系的净光合速率的总平均值(μmol CO₂·m^-2·s^-1)排序为：无性系9^#（8.53）>6^#>（7.21）3^#（6.47）>8^#（4.98）；蒸腾速率的总平均值(mmol H₂O·m^-2·s^-1)排序为：无性系9^#（3.74）>3^#（2.76）>6^#（1.76）>8^#（1.47）；水分利用效率的总平均值(mmol CO₂·mol^-1 H₂O)排序为：无性系8^#（4.77）>6^#（4.35）>3^#（2.99）>9^#（2.40）。4个无性系的净光合速率与水分利用效率的排序并不一致。9^#属于高光合、高蒸腾、低水分利用效率类型，8^#属低光合、低蒸腾、高水分利用效率类型。在6月份6^#无性系的净光合速率和水分利用效率与温度、湿度显著相关，3^#、8^#、9^#无性系与光合有效辐射和气孔导度密切相关。

A comparison of photosynthethetic characteristics in four poplar clones

The photosynthetic characteristics and the relationship of net photosynthetic rate, water use efficiency with the environmental factors and stomatal conductance in four new poplar clones (3^#、6^#、8^#、9^#) were studied. The results showed that the peak value of the diurnal courses of the photosynthetic rate generally appeared around 10:00, and then reduced gradually. The diurnal courses of transpiration rate in different months were different. The peak value of the diurnal courses of stomatal conductance generally appeared at 7:00~9:00. The total mean net photosynthetic rate(μmol CO₂·m^-2·s^-1), transpiration rate (mmol H₂O·m^-2·s^-1) and water use efficiency (mmol CO₂·mol^-1 H₂O) had following order in June, July and August respectively: Clone 9^#（8.53）>6^#（7.21）>3^#（6.47）>8^#（4.98）; Clone 9^#（3.74）>3^#（2.76）>6^#（1.76）>8^#（1.47）; Clone 8^#（4.77）>6^#（4.35）>3^#（2.99）>9^#（2.40）. Clone 9^# had higher net photosynthetic rate and transpiration rate, with lower water use efficiency. On the contrary, clone 8^# had lower net photosynthetic rate and transpiration rate, with higher water use efficiency. Net photosynthetic rate and water use efficiency had a close relationship with the air temperature and relative humidity in 6^#, and had a close relationship with the photosynthetic active radiation and stomatal conductance in 3^#、8^# and 9^#.