Gender differences of Humulus scandens seedlings in response to NaCl stress

In this study, we examined sex-specific differences in leaf area, gas exchange parameters, leaf water potential and chlorophyll fluorescence of male and female seedlings of Humulus scandens under NaCl stress (0, 100, 200 and 300 mmol·L-1 NaCl). Under the effects of NaCl, the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), leaf water potential (ψw), catalase (CAT), limiting value of stomata(Ls) and malondialdehyde (MDA) of male and female seedlings increased gradually. The leaf area of single leaves increased first and then decreased. The maximum fluorescence (Fm), the variable fluorescence (Fv), the potential activity of PSⅡ (Fv/Fo) and the non-photochemical quenching coefficient (qN) of the females gradually increased with the increase of NaCl stress. The photochemical quenching coefficient (qP) and chlorophyll content decreased by degrees. Overall, the ETR, Fv, Fv/Fm and Fv/Fo of the males showed an increasing trend, but qN and qP decreased, while chlorophyll content increased first and then decreased. Therefore, the physiological and biochemical characteristics such as single leaf area, chlorophyll content, chlorophyll fluorescence, gas exchange, and CAT and MDA contents in male and female seedlings of H. scandens were affected by NaCl stress. There were significant gender differences in the response of male and female seedlings to NaCl stress. Compared to the males, the females had greater resistance against NaCl stress.