高氯酸盐对空心莲子草生长及叶绿素荧光参数的影响

Effects of Perchlorate on Growth and Chlorophyll Fluorescence Parameters of Alternanthera philoxeroides

高氯酸盐是一种新型的持久性污染物,其对植物影响作用的研究国内外鲜见报道.以空心莲子草为实验材料,在水培及可控条件下,探讨不同浓度(1、5、20、100、500 mg/L)ClO4-对空心莲子草生长及生理的影响.结果表明,①不同浓度的ClO4-处理均不同程度地抑制根、茎、叶生物量及单株相对生长量,其中根生物量对照与各浓度处理之间均存在显著差异.处理40d后,各浓度(由低到高)处理的相对生长量分别为对照的61.6%、60.8%、53.1%、20.4%和3.3%;ClO4-处理下根、茎、叶生物量的变异系数大小依次为:叶>根>茎;ClO4-处理使根茎叶三者之间的生物量分配关系发生变化,使茎的生物量分配系数增大,而叶降低,其中100、500 mg/L ClO4-处理组与对照相比差异显著;②不同浓度的ClO4-处理均使空心莲子草幼叶出现明显的伤害症状,顶叶反卷、叶缘变黑、焦枯,受害程度随处理浓度及时间的增加而加重;③ClO4-处理使叶片SPAD值、Fv/Fm、F′v/F′m、ΦPSⅡ、ETR、ETRmax等荧光参数均出现不同程度的下降趋势,SPAD、ΦPSⅡ等荧光参数可以作为反映受ClO4-胁迫影响的内在敏感生理指标.以上结果说明高氯酸盐处理会导致空心莲子草光合系统的损伤及光化学效率的下降,抑制其生长,并使叶片产生明显伤害.空心莲子草各器官对ClO4-的敏感程度以叶和根较高,茎较低.

Perchlorate is a new emerging persistent pollutant, while no studies about its effects on plants have been reported both home and abroad. In order to explore the effects of perchlorate on growth and physiology of aquatic plant, Alternanthera philoxeroides were treated by 1/20 Hoagland nutrient solution with different concentrations （0, 1, 5, 20, 100, 500 mg/L） of ClOg under the controlled conditions. The results showed as follow. （1）Under perehlorate treatment, relative growth yield, dry weight of root, shoot and leaves were inhibited at different degrees, in which root biomass under different treatments showed significant difference to the control. After treatment for 40 d, relative growth yield of different treatments at concentration from 1 mg/L to 500 mg/L were about 61.6%, 60.8%, 53.1%, 20.4% and 3.3% separately of the control. And the order of variation coefficients of biomass in different organ were as follows： leaf 〉 root biomass 〉 stem; the relationship of biomass allocation in different organs of Alternanthera philoxeroides under perchlorate treatment changed, and the proportion of stem biomass increased, while leaf decreased, in which 100 and 500 mg/L ClO4- treatment showed significant difference to the control. （2）Under perchlorate treatment, young leaves of Alternanthera philoxeroides presented injury symptoms（such as parietal roiling reversely, leaf edge getting black and withered etc）, and the damaged degree of Alternanthera philoxeroides increased with the increase of treatment concentration and time. （3）Under perehlorate treatment, the relative chlorophyll content（SPAD value） ,primary maximal PS Ⅱefficiency（ Fv/Fm ）, efficiency of excitation capture by open PS Ⅱ centre （F＇v,/F＇m ）, actual photochemical efficiency of PS Ⅱ （ФpsⅡ ）, electron transport rate （ETR）, maximal electron transport rate（ETRmax ） and other indexes were inhibited at different degrees. SPAD and chlorophyll fluorescence parameters ФpsⅡ etc could be used as sensitive physiological indexes to reflect the effects of perchlorate stress. The results suggest that perehlorate treatment can damage the photosynthetic system and leaf, decrease photochemical efficiency, and inhibit growth of Alternanthera philoxeroides. Leaf and root show a higher sensitivity to perchlorate, while stem with a lower sensitivity.