Abstract
Submerged plants are the pioneer species of eutrophic water remediation, and they are important for maintaining the health of aquatic ecosystem, while light is the main limiting factor for the growth of submerged plants. In this study, we measured the maximal quantum yields of photosystemⅡ(Fv/Fm) and rapid light curves (RLCs) of five dominant submerged macrophytes in situ by using pulse-amplitude modulated fluorometer (Diving-PAM). Results revealed that P. crispus L. and M. verticillatum L. had the highest Fv/Fm value, all species’ Fv/Fm are less than 0.8. In addition, the variation trends of Fv'/Fm' and Fv/Fm were same. All species showed statistically significant differences in α, while P. crispus L. and M. verticillatum L. showed the highest α value in the five species. And the variation trends of rETRm and Ek were basically the same. It indicated that P. crispus L. and M. verticillatum L., both of which had high photosynthetic efficiency, had excellent ability to withstand hard light. Compared five species, P. crispus L. and M. verticillatum L. had resistance capacity to hard light as well as faster photosynthetic rate, and V. natans (Lour.) Hara had higher resistance capacity to low light. Thus, when submerged plants are used for water restoration, V. natans (Lour.) Hara could be regarded as a pioneer species in eutrophication water restoration. P. crispus L. and M. verticillatum L. will have better effects when used in shallow water areas.
Highlights
H. verticillata, M. verticillatum L., P. crispus L. and P. wrightii Morong (all these submerged plants were identified by Flora of China (Wu, 2007)) were selected as the research objects, and their leaf green fluorescence parameters were determined in situ by Diving-PAM
The fluorescence before turning on the saturation pulse was recorded as Ft, and the fluorescence measured after turning on the saturation pulse light was recorded as Fm', we got variable fluorescence (△F):△F=Fm'-Ft,the effective quantum yield (Y) can be calculated: Y=(Fm'-Ft)/Fm'=△F/Fm' Relative electron transport rate was described by the equation (Ralph et al, 1998): rETR=Y×PAR×0.5×0.84 The least square method was used for the fast light curve fitting, and the equation we used is proposed by Platt (Platt et al, 1980). and Ralph (Ralph and Gademann, 2005)
There is no significant difference in Fv/Fm between H. verticillata and P. crispus L. (P
Summary
Received in revised form: 06 Apr 2021. From Volume 49, Issue 1, 2021, Notulae Botanicae Horti Agrobotanici Cluj-Napoca journal uses article numbers in place of the traditional method of continuous pagination through the volume. The journal will continue to appear quarterly, as before, with four annual numbers
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