水位变化及退水恢复对藜蒿生长和生理的影响

Effects of water level change and normal moisture after waterlogging on the growth and physiology of Artemisia selengensis

植物在周期性变化的水位中存活和退水后的恢复状况体现了其对水淹的适应能力。为深入了解鄱阳湖典型湿地植物藜蒿(Artemisia selengensis)对水淹胁迫的耐受能力,研究了藜蒿植株对3种水环境处理下及退水恢复后形态特征、生理指标的响应。实验采用双套盆法,共设置上升、下降和稳定3种处理。上升水位组:设置6个水位,水位均从0 cm开始每日增加高度,处理强度分别为0.1、0.2、0.3、0.4、0.5、0.6 cm·d^(-1),即50 d后水位分别为5、10、15、20、25、30 cm;下降水位组:设置6个水位,水位分别从5、10、15、20、25、30 cm开始每日降低高度,处理强度同上升水位组,即50 d后水位均为0 cm;稳定水位组:设置6个水位,分别为5、10、15、20、25、30 cm,试验期间水位保持恒定。另外,设置水位0 cm(即培养盆中水刚好没过土壤表面)的对照组。水位波动处理时间50 d和退水恢复时间10 d,共60 d。结果表明:(1)3种水位环境类型中,当水位低于15 cm时,株高增幅、叶片数呈逐渐上升趋势;当水位高于15 cm时,株高增幅呈降低趋势、叶片数有所减少,其中上升水位中处理强度为0.1~0.3 cm·d^(-1)的株高、叶片数明显优于对照组。(2)上升水位中,处理强度0.3 cm·d^(-1)为藜蒿水淹耐受范围,当处理强度小于0.3 cm·d^(-1)时,抗氧化酶活性变化与大于0.3 cm·d^(-1)存在明显差异;下降水位由于受到初始水位影响,超氧化物歧化酶和过氧化氢酶活性在10~20 d时活性达到最大;稳定水位中,淹水深度为10、15 cm,抗氧化酶活性均不断增加。超氧化物歧化酶、过氧化氢酶活性随水淹时长推移和胁迫强度的增加不断下降,而过氧化物酶活性不断增大。(3)3种水位环境类型中,超氧阴离子产生速率和丙二醛含量在低强度胁迫中与对照组无显著性差异(P>0.05),且试验前期与抗氧化酶活性变化显著相关;高强度处理组的超氧阴离子产生速率和丙二醛含量随着淹水深度与试验时间增加而增加,且显著高于对照组。(4)退水后,低强度处理组各项指标均能迅速恢复,且与对照组无明显差异(P>0.05);高强度处理组各项指标恢复缓慢或不能完全恢复。因此,藜蒿适合在短时间内、低强度水位变化的环境下作为生态修复和重建的主要植物。

Plant survival in cyclically changing water levels and the recovery after water recession reflect their adaptability to flooding.To better understand the tolerance to flooding stress of Artemisia selengensis,a typical wetland plant in Poyang Lake,we examined the morphological and physiological responses of A.selengensis to three kinds of water environment and after water withdrawal and recovery.The double-pot method was adopted,with three water levels(rising,falling and stabilizing)being set up.In the rising water level group,six water levels were set up,which all initially increased from 0 cm,with an increasing intensity of 0.1,0.2,0.3,0.4,0.5 and 0.6 cm·d^(-1),respectively,with final water levels being 5,10,15,20,25,and 30 cm respectively after 50 days.In the descending water level group,six water levels were set up,the water levels were decreased from 5,10,15,20,25 and 30 cm,with a decreasing intensity of 0.1,0.2,0.3,0.4,0.5 and 0.6 cm·d^(-1)respectively,and all the final water levels were 0 cm after 50 days.In the stable water level group,six water levels were set up,which were 5,10,15,20,25 and 30 cm respectively,and the water levels remained constant.A control group with the water level of 0 cm was set up(the water level in the pot just submerged the soil surface).The treatment time of water level fluctuation was 50 days and the normal moisture after waterlogging time was 10 days,resulting in a total of 60 days.Results showed that:(1)In the three water level environment types,when water level was lower than 15 cm,the increases of plant height and the number of leaves showed a gradual upward trend.However,when the water level was higher than 15 cm,the growth rate of plant height and the number of leaves decreased.In the rising water level group,plant height and the number of leaves with the treatment intensity of 0.1-0.3 cm·d^(-1)were significantly higher than the control group.(2)In the rising water level,the treatment intensity of 0.3 cm·d^(-1)was within the tolerance range of A.selengensis to waterlogging.When the treatment intensity was less than 0.3 cm·d^(-1),the change of antioxidant enzyme activity was obviously different from that of more than 0.3 cm·d^(-1).Affected by the initial water level,the activities of superoxide dismutase and catalase of A.selengensis in the falling water level reached the maximum at 10-20 days.In the stable water level,when the waterlogging depth was 10 and 15 cm,the antioxidant enzyme activity increased continuously.The activities of superoxide dismutase and catalase decreased with increasing waterlogging time and stress intensity,whereas peroxidase activity showed an increasing trend.(3)Among the three types of water level environment,the superoxide anion production rates and malondialdehyde content did not differ from that in the control group under low intensity stress(P>0.05),which were correlated to the antioxidant enzyme activity in the early stage of the experiment.The superoxide anion production rates and malondialdehyde content in high intensity treatment group increased with increasing waterlogging depth and duration,and were significantly higher than those in control group.(4)In normal moisture condition after waterlogging,all indices of low-intensity treatment group recovered quickly and had no significant difference with that of the control group(P>0.05).The indices of high intensity treatment group recovered slowly or not completely.Therefore,A.selengensis is suitable for ecological restoration and reconstruction in the short-term and in a low-intensity-alteration water environment.