不同水淹条件下河岸带优势植物类群的生理与生态响应特征

为探究水淹胁迫下河岸带植物的生理和形态变化特征及其响应机制，以乐安河河岸带采集的优势植物类群狗牙根（Cynodon dactylon）、牛鞭草（Hemarthria altissima）、喜旱莲子草（Alternanthera philoxeroides）和蓼子草（Polygonum hydropiper）为材料，在室内进行土壤盆栽培养，利用钢化玻璃水缸控制水位，设置对照、浸润、半淹、全淹4种不同水淹胁迫条件，测定不同胁迫周期各物种的叶绿素含量、光合指标、荧光参数、荧光成像的变化及形态学变化特征，分析各物种对水淹胁迫的抗逆响应.结果表明:短时间（7 d）水淹胁迫下，浸润组、半淹组和全淹组各植物的w（Chlt）（叶绿素总量）、P_n（净光合速率）、T_r（蒸腾速率）、QY_max（最大量子产率）、株高、叶片数等指标与对照组相比总体呈降低趋势，其中浸润组植物叶片中w（Chlt）、P_n、QY_max等均略高于对照组（CK），而C_i（胞间CO₂浓度）呈上升趋势，NPQ_lss（非光化学淬灭）呈先降后升趋势；长时间（14 d）水淹胁迫下，各植物的上述生理、形态学指标的变化规律与短时间水淹胁迫下基本一致，其中全淹条件下各植物的w（Chlt）、P_n和叶片数在较短期水淹胁迫下大幅下降，各植物3个指标分别显著（P < 0.05）低于对照组，显著差异值分别为:狗牙根100%、100%、100%；牛鞭草62.3%、67.9%、63.8%；喜旱莲子草73.6%、83.2%、89.6%；蓼子草54.5%、100%、100%，狗牙根和蓼子草在全淹条件下接近死亡.研究显示，水淹胁迫对4种植物的生长有不同程度的抑制，同时植物也做出抵消胁迫的抗逆响应. 

Physiological and Ecological Response Characteristics of Dominant Plant Groups in Riparian Zone under Different Flood Conditions

This paper aims to explore the physiological and morphological characteristics and response mechanism of riparian plants under water flooding stress.Dominant plant species, such as Cynodon dactylon, Hemarthria altissima, Alternanthera philoxeroides and Polygonum hydropiper, were collected from the riparian zone of the Le'an River and cultured indoor using soil pot methods.The water level was controlled by a toughened glass tank.Different water flooding stress conditions were set up as follows:control group, infiltration, half flooded and fully flooded.We measured the changes of chlorophyll contents, photosynthetic parameters, fluorescence parameters, fluorescence imaging and morphology at different periods of water stress, and analyzed the above indexes reflected in the level of community and the resilience response mechanism of the plant groups under the water flooding stress.Under the short-term water stress condition, our results showed that the degree of total chlorophyll(Chlt), net photosynthetic rate(P_n), transpiration rate(T_r), intercellular CO₂ concentration(C_i), maximum quantum yield(QY_max), plant height and leaf number of each plant were decreased compared with the control group.However, the average contents of Chlt, P_n and QY_max in the infiltration group were slightly higher than those of the control group.The concentration of intercellular CO₂(C_i) was elevated, while the values of non-photochemical quenching decreased first and then increased.The physiological and morphological indexes of the four plant species under the long-term water stress were comparable to the short-term water stress.The P_n and leaf number in the fully flooded groups were significantly decreased compared to the corresponding short-term water stress groups.The values of w(Chlt), P_n and leaf numbers of C.dactylon, H.altissima, A.Philoxeroides and P.hydropiper were significantly lower than those of the control group(P < 0.05).The significant difference values of the above three parameters for C.dactylon were 100%, 100% and 100%;the values for H.altissima were 67.9%, 63.8% and 62.3%;those for A.philoxeroides were 73.6%, 83.2% and 89.6%;and those for P.hydropiper were 54.5%, 100% and 100%, respectively.All plants of C.dactylon and P.hydropiper died in the fully flooded groups.The research suggests that there are different effects from water stress under the different water levels for the four plants, as well as the resistance of the plants to counteract the effect of water stress.