Chlorophyll fluorescence and excitation energy dissipation of pot-grown Phyllostachys rivalis leaves after long-term flooding

To determine the physiological and biochemical responses and adaptive mechanisms of Phyllostachys rivalis to long-term soil flooding, two-year-old potted seedlings of Ph. rivalis were subjected to different flooding depths. The flooding treatment was set with water levels of 5 cm (TreatmentⅠ) and 10 cm (TreatmentⅡ) higher than the soil surface and normal water supply (ck). Then the chlorophyll fluorescence parameters in leaves were determined after continuous flooding for 30, 90, 180, 270, and 360 d. Responses to the continuous flooding stress for light energy absorption and transformation, energy transfer and distribution, reaction center activity, and excitation energy dissipation in leaves of three leaves per seedlings and three seedlings were measured and analyzed. A one-way analysis of variance with duncan's test was conducted at a significant level of 0.05. Results showed that the chlorophyll fluorescence parameters varied with different flooding levels. When flooding for 30 d and 90 d, minimal fluorescence (Fo), maximum fluorescence (Fm), photochemical maximum efficiency of PS Ⅱ (Fv/Fm), photochemical quenching coefficient (qP), and electron transport rate(RET) of Treatment Ⅰ were not significantly different (P > 0.05) compared with ck; however, Treatment Ⅱ when flooding for 90 d compared with ck was significantly increased for Fo while significantly decreased for Fm, Fv/Fm and RET (P 0.05). The amount of absorbed light in photochemistry (P) and excess energy (E) increased first and then decreased (P < 0.05), but the energy of dissipation of the antenna heat dissipation (D) observed were opposite. Taken together, Ph. rivalis could maintain a relatively high RET, qP, and P in the early stages of flooding, and enhance qN to regulate their energy metabolism, dissipate excess light energy via heat dissipation, thereby alleviating the light photoinhibition and photooxidation; however, continuous long-term soil flooding could damage photosystem Ⅱ (PS Ⅱ) even though there was minimal adverse effect on the functional center of PS Ⅱ (P < 0.05). It can be inferred that Ph. rivalis can tolerate a short term flooding which facilitate its possible application in plantation restoration of riparion zone.