Different eco-physiological responses between male and female Populus deltoides clones to waterlogging stress

Abstract

Sex-related variations in response to waterlogging stress between male clones ( Populus deltoides CL. ‘Juba’) and female clones ( P. deltoides CL. ‘Danhong’) in a semi-controlled environment were investigated. All tested plants survived after a ten-week waterlogging treatment with 5 cm of water above the soil surface. This suggests that the two clones belonged to waterlogging-tolerant species, so that they can be applied in the construction of riparian protection forests and the restoration of wetlands. Compared with well-watered treatment, waterlogging treatment significantly decreased shoot height, stem diameter, leaf number, mean leaf area, total leaf area, relative water content (RWC), specific leaf area (SLA), total chlorophyll concentration (chlorophyll a + b, TC), carotenoids (Caro), net photosynthetic rate ( A), stomatal conductance ( gs), instantaneous water use efficiency (WUEi), maximum efficiency of PSII ( F v/ F m), maximum effective quantum yield of PSII (Yield), and soluble sugar content and significantly increased levels of superoxide anion radical ( O 2 - ), hydrogen peroxide (H 2O 2), proline, reducing sugar, peroxidase (POD) activity, and superoxide dismutase (SOD) activity. The effects of waterlogging on chlorophyll a/chlorophyll b ratio, TC/Caro ratio, intercellular CO 2 concentration ( Ci), transpiration ( E), photochemical quenching coefficient (qP), and non-photochemical quenching coefficient (qN) were not significant. In well-watered conditions, females had significantly faster growth rate and higher TC, Caro, and A than males. In contrast, males exhibited higher values of RWC and WUEi; less reductions in SLA, TC, Caro, and A; higher levels of POD and SOD activities; higher proline and reducing sugar contents; and lower O 2 - and H 2O 2 levels than females under waterlogging conditions. Findings indicate that males have better cellular defense mechanisms against damage caused by waterlogging stress than females, whereas females were more responsive to waterlogging stress than males.