两种园林植物断根和剪枝后蒸腾和光合特性的变化研究

Characteristics of transpiration and photosynthesis of two gardening trees after root and branch pruning

选择移栽难易程度差异很大的两种园林树木(小叶榕Ficusmicrocarpa和拟单性木兰parakmeriaomeiensis)进行断根和不同程度的剪枝,模拟移栽,形成不同的成活水平个体,比较不同成活水平下蒸腾、光合等生理机能的差异,以期从生理生态角度了解影响成活的关键因子。结果表明,①小叶榕相对拟单性木兰移栽成活率高,主要是处理后,小叶榕气孔导度能很快降低,导致蒸腾速率降低,耗水量显著减小;而拟单性木兰处理后气孔导度和蒸腾速率都升高,主要依靠剪枝来降低植株蒸腾耗水,降低幅度不大。小叶榕日平均蒸腾速率显著高于拟单性木兰,两者日平均耗水量都随剪枝程度的增加而减少,即重度剪枝最容易成活。②拟单性木兰净光合速率与气孔导度都显著相关,而小叶榕净光合速率与气孔导度的相关性较差。小叶榕日平均光合速率显著高于拟单性木兰,种或处理间日变化趋势也都存在差异。③小叶榕处理后水分利用效率变化趋势不同于对照,但处理之间日变化趋势类似,随处理的增加日平均值降低;拟单性木兰处理以及对照间变化趋势有很大差异,但日平均值相差不大,都显著高于对照。仍需进一步研究内部机理,找到解决成活的更有效措施。

Two gardening trees （Ficus microcarpa and Parakmeria omeiensis）, with distinct survival rates, were chosen to study. Roots and different amount of branches were pruned to represent different survival probabilities. Photosynthesis rate, transpiration rate and stomatal conductance were observed before and after root pruning and compared among trees with different survival probabilities, so as to find crucial factors in survival rate from physiological ecology, The results are as follows： ① Compared with Parakmeria omeiensis, Ficus microcarpa is more sensitive to root pruning, and it can rapidly reduce stomatal conductance and transpiration rate to reduce water consumption, therefore, Ficus microcarpa has higher survival probability. On the contrary, stomatal conductance and transpiration rate of Parakmeria omeiensism increased and the decrease of water consumption mainly depended on branches pruned. The daily average of transpiration rate for Ficus microcarpa is higher than that for Parakmeria omeiensism, and daily mean water consumption of both species decreased while amount of pruned branches increased. ② Photosynthesis rate of Parakmeria omeiensis is remarkably correlated with stomatal conductance while the relationship between photosynthesis rate and stomatal conductance of Ficus microcarpa is not significant. The daily average of photosynthesis rate for Ficus microcarpa is higher than that for Parakmeria omeiensi, and diurnal variations of each species differ among treatments. ③Diurnal variations of WUE for the two gardening trees changed after root pruning, and the daily mean WUE ofFicus microcarpa increased with amount of pruned branches increasing while that of Parakmeria omeiensi is similar among treatments and contrast. We need more researches on the physiological mechanisms of trees so as to find more effective solutions to transplanting.