Chin J Plant Ecol ›› 2019, Vol. 43 ›› Issue (8): 685-696.DOI: 10.17521/cjpe.2019.0132

• Research Articles • Previous Articles     Next Articles

Morphological and photosynthetic physiological characteristics of Saussurea salsa in response to flooding in salt marshes of Xiao Sugan Lake, Gansu, China

LI Qun,ZHAO Cheng-Zhang(),WANG Ji-Wei,WEN Jun,LI Zi-Qin,MA Jun-Yi   

  1. College of Geography and Environmental Science, Northwest Normal University, Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, Lanzhou 730070, China
  • Received:2019-05-30 Revised:2019-08-09 Online:2019-08-20 Published:2020-01-03
  • Contact: ZHAO Cheng-Zhang ORCID:0000-0002-0127-8405
  • Supported by:
    National Natural Science Foundation of China(41861009);National Natural Science Foundation of China(41461013)

Abstract:

Aims The response of plant leaf functional traits to flooding in salt marshes is not only helpful in exploring the internal correlation between leaf plasticity mechanism and photosynthetic characteristics, but also of vital significance for gaining a better understanding on the stress resistance strategies of plants in salt marsh wetlands. The aim of this study is to investigate the responses of leaf functional traits of Saussurea salsa to flooding with the changes of water-logging durations.
Methods The research site was located in provincial migratory bird nature reserve in Xiao Sugan Lake, Gansu Province, China (39.22°-39.35° N, 94.45°-94.59° E). A sample belt was selected from the edge of the lakeshore to the end of the perennial tidewater line in the low-lying area along the north side of Xiao Sugan River. The duration of water-logging in the salt marsh wetland was measured base on the water level marked by the flood rise and retreat marks in Xiao Sugan Lake over the years. The sample belt was divided into 3 plots according to the water-logging duration: low flooding area (water-logging duration: 30-90 days); medium flooding area (water- logging duration: 90-150 days); and deep flooding area (water-logging duration: 150-210 days). Six subplots (2 m × 2 m) of S. salsa were selected from each of the three plots for a total of 18 subplots. We investigated community characteristics and population traits of S. salsa, soil moisture and soil electrical conductivity (EC). Six plants per subplot were selected for photosynthesis and chlorophyll fluorescence measurements. Foliar samples collected from each of the six S. salsa were taken to the laboratory for measurements of leaf traits (leaf area, thickness, dry mass and chlorophyll content).
Important findings The results showed that S. salsa changed the covariation strategy of S. salsa foliar morphology and photosynthesis with the extension of water-logging duration. In the low flooding area, S. salsa adopted fleshy lobular pattern with small specific leaf area (SLA), high effective quantum yield of photosynthetic system II (PSII) photochemistry in light (Y(II)) and low quantum yield of regulated energy dissipation (Y(NPQ)). However, S. salsa grew in the deep flooding area adopted completely opposite covariation strategy in foliar morphology and photosynthesis compared with those grew in the low flooding area. We observed a significant correlation between SLA and Y(II), photochemical quenching (QP), and Y(NPQ), as well as a significant positive correlation between the quantum yield of non-regulated energy dissipation (Y(NO)) and chlorophyll a content (Ca), chlorophyll b content (Cb) in all of the three plots. Under the influence of the spatio-temporal evolution pattern of still water in the flooded area of Xiao Sugan Lake, S. salsa population achieved the balance of the photosynthetic carbon budget by changing the morphological characteristics of leaves, such as leaf area, leaf thickness and SLA, timely adjusting the photosynthetic characteristics, such as Y(NPQ) and Y(II). Saussurea salsa showed strong tolerance to water and salt heterogeneity, reflecting the leaf plasticity and resistance mechanism of salt marsh wetland plant under extreme environments.

Key words: leaf traits, specific leaf area, actual photochemical efficiency of PSII, Saussurea salsa, Xiao Sugan Lake