模拟长江滩地水淹胁迫对3种树种幼苗生理生态特征的影响

通过模拟长江滩地季节性水淹发生的情况,研究水淹胁迫对枫杨、夹竹桃、乌桕3个树种幼苗生长特征、生物量分配、光合响应参数以及叶绿素等的变化特征,揭示了3种树种对长江滩地水淹环境的生理生态学响应。结果表明:除枫杨在重度水淹中全部死亡,其他树种存活率达到100%。短期轻度水淹在一定程度上促进了植物地径的生长,而长期轻度水淹和重度水淹均对地径和株高生长具有显著的抑制作用。水淹胁迫对3种树种幼苗生物量累积抑制作用明显,且重度水淹导致夹竹桃和乌桕树种根冠比较对照显著降低,分别降低41.66%和37.82%。同时,长期轻度水淹和重度水淹导致3种树种幼苗最大净光合速率和叶绿素质量分数显著降低,而轻度水淹退水后又明显上升。光补偿点、表观量子效率以及暗呼吸速率则均未表现出显著变化,但仍可看出暗呼吸速率呈现明显增加的趋势。枫杨和乌桕的光饱和点明显降低,而夹竹桃则无显著变化。综上可知,夹竹桃、乌桕和枫杨均具有较强的耐水淹特性,均适宜季节性水淹江滩生长,但淹水时间不宜过长,且枫杨的淹水深度不宜过深。

Effects of Waterlogging Stress on Ecophysiological Characteristics of Tree Seedlings of Three Species in Flooding Land of Yangtze River

By simulating the seasonal flooding of Yangtze River, we studied the growth characteristics, biomass allocation, light response parameters and chlorophyll change characteristic of Pterocarya stenoptera, Nerium indicum, Sapium sbe iferum un-der different Waterlogging stress, and revealed the physiological ecology response of the three species to flooding land of Yangtze River.The survival rates of seedlings were 100%during a flooding period under the severe waterlogging stress in addition to P.stenoptera seedlings.Short-term mild waterlogging promoted the plant diameter growth, while long-term mild waterlogging and severe waterlogging had a significant inhibitory effect on the diameter and height growth.The seedling bio-mass accumulation of three species were all inhibited obviously under waterlogging stress, and the root-shoot ratio contrast of N.indicum and S.sebiferum reduced by 41.66%and 37.82%under the severe waterlogging stress, respectively.Mean-while, the long-term mild waterlogging and the severe waterlogging stress led to a significant decrease of maximum net pho-tosynthetic rate and chlorophyll mass fraction, which under the mild waterlogging stress were increased after the water rece-ded.The light compensation point, apparent quantum yield and dark respiration rate showed no significant change to water-logging stress, but the dark respiration rate still appeared increasing trend evidently.The light saturation point of P. stenoptera and S.sebiferum were significantly decreased under waterlogging stress, while that of N.indicum showed no sig-nificant change.Therefore, all of these species have strong water resistance properties and are suitable for growth in the seasonally flooded marshland, but the long flooding time is inappropriate, and the flooding depth for P.stenoptera should not be too deep.