Photosynthetic traits of Carex cinerascens in flooded and nonflooded conditions

Abstract

Gas exchange of Carex cinerascens was carried out in Swan Islet Wetland Reserve (29°48′ N, 112°33′ E). The diurnal photosynthetic course of C. cinerascens in the flooded and the nonflooded conditions were analyzed through the radial basis function (RBF) neural network approach to evaluate the influences of environmental variables on the photosynthetic activity. The inhibition of photosynthesis induced by soil flooding can be attributed to the reduced stomatal conductance (g s ), the deficiency of Rubisco regeneration and decreased chlorophyll (Chl) content. As revealed by analysis of artificial neural network (ANN) models, g s was the dominant factor in determining the photosynthesis response. Weighting analysis showed that the effect of water pressure deficit (VPD) > air temperature (T) > CO 2 concentration (C a ) > air humidity (RH) > photosynthetical photon flux density (PPFD) for the nonflooded model, whereas for the flooded model, the factors were ranked in the order VPD > C a > RH > PPFD > T. The different photosynthetic response of C. cinerascens found between the nonflooded and flooded conditions would be useful to evaluate the flood tolerance at plant species level.

Photosynthetic parameters of a sedge-grass marsh as a big-leaf: effect of plant species composition

“…These R d values are consistent with those obtained for C. acuta, G. maxima and C. canescens by Ondok and Gloser 36 . R d values similar to those of our selected plant species are also consistent with values reported for other wetland plant species such as Schoenoplectus hallii: − 1.3 ± 0.6 μmol m −2 s −1 43 , Phragmites australis: − 2.62 ± 0.11 μmol m −2 s −1 and Carex cinerascens − 1.58 ± 0.09 μmol m −2 s −1 44 , 45 . Experimentally measured R d in P. arundinacea was about − 0.35 μmol m −2 s −1 in the control treatment and − 0.66 μmol m −2 s −1 in the submergence treatment 46 .…”

“…In C 3 plants, it is 15 μmol m −2 s −1 on the average 29 44 . Flooding usually increased the I comp , like the effect of canopy gaps 44,45 . Our calculated I comp values are within the range reported for Carex species 52 and are highly variable.…”

“…The I comp of Phragmites australis and Carex cinerascens were about 48.5 and 37.8 μmol m −2 s −1 , respectively 44 . Flooding usually increased the I comp , like the effect of canopy gaps 44 , 45 .…”

“…Wetland plants tolerate fluctuating water levels and can also survive submergence during floods. Photosynthesis of emergent plants under water is inhibited due to reduced stomatal conductance 45 , decreased availability of PPFD 55 , high photorespiration 56 and decrease of chlorophyll content 45 . In our case the flood effect was not significant due to the short duration of the flooding (only 11 days).…”