Effects of water depth gradient on physiological characteristics of Vallisneria natans

Abstract

For the purpose of studying the response of the Vallisneria natans antioxidant enzyme defense system to different water depths, we selected seedlings with well-preserved rhizomes, consistent germination and positive growth as experimental plants and put them into 10 plexiglass barrels at depth gradients. After 60 days of simulation experiments, we tested the malondialdehyde (MDA), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), chlorophyll and soluble protein contents and root activity. The results showed that (1) the contents of Chla, Chlb, Chl (a + b) and Car first increased with water depth and then decreased, reaching maximum values of 0.99, 0.38, 1.37 and 0.20 mg/g, at 110 cm respectively; (2) SOD and POD decreased with increased water depth, with a significant decreasing trend particularly between 30 and 60 days, and MDA showed the same trend as POD. CAT decreased with increased water depth but then showed a two-fold increase trend, probably due to the gradual effects of long-term water stress the antioxidant enzyme system in V. natans leaves. (3) Soluble protein had the same trend as MDA. Root activity implied that the more active the root system is, the more ramets and biomass are produced. In this experiment, the plant grew well at depths of less than 120 cm and showed clear signs of aging or death beyond this depth; the results showed that the antioxidant enzyme defense system engaged a series of antioxidant protection mechanisms to increase plant stress resistance ability and reduce or eliminate the damage of plants, but when the stress increased beyond the tolerance of the plant, the antioxidant defense system was destroyed, which eventually led to the death of the plant.

Keywords:

• Vallisneria natans
• water depth gradient
• antioxidant enzyme

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This research was supported by the Natural Scientific Foundation of China (41361017, 41661102), the Natural Scientific Foundation of Jiangxi Province (20181BAB203021), the Youth Natural Scientific Foundation of China (41603077).

Additional information

Notes on contributors

Yun Cao

Cao Yun received his PhD from Nanjing Normal University in 2007. His research interests are in plant ecology and ecological restoration in wetlands. He is currently working on a research project about the ecological amplitude of beach-typical vegetation in Poyang Lake under a water level gradient.

 

Dan Chen

Chen Dan is a graduate student at Jiangxi Normal University. Her research interest is in submerged vegetation restoration.

 

Xin-Sheng Ji

Ji Xin-Sheng is a graduate student at Jiangxi Normal University. Her research interest is in submerged vegetation restoration. She is currently working on understanding the influence of environmental factors on the growth of submersed macrophytes.

 

Su-Juan Zhang

Zhang Su-Juan received her master's degree from Jiangxi Normal University in 2016. Her research interest is in submerged plants of Poyang Lake. She is currently working on the spatial-temporal changes of the submerged plant V. natans driven by hydrological systems in Poyang Lake.

 

Qi Huang

Huang Qi received his PhD form Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences. His current research explores the ecologically relevant water quality criteria for shallow dish lakes in Poyang Lake wetlands.

 

Wen-Lin Wang

Wang Wen-Lin received his PhD from Nanjing Normal University in 2014. His research interests are in wetland ecology and ecological restoration in wetlands. He is currently working on a research project about the characteristics and regulatory mechanisms in the oxygen-rich of the urban black-odor river sediment microinterface.