We applied under pot-culture conditions and the double-casing pot method to study the characteristics of photosynthetic gas exchange and chlorophyll fluorescence in the leaves of Physocarpus amurensis Maxim （PA） and...We applied under pot-culture conditions and the double-casing pot method to study the characteristics of photosynthetic gas exchange and chlorophyll fluorescence in the leaves of Physocarpus amurensis Maxim （PA） and Physocarpus opulifolius under flooding stress. Our results indicate a significantly higher flooding tolerance of P. opulifolius compared to P. amurensis. Especially in P. amurensis, the limitation of non-stomatal factors played a major role in the advanced stages of flooding stress, observed as a rapid increase of the intercellular C02 con- centration （Ci） and a decrease of the stomatal limitation value （Ls）. The maximal PSII photochemical efficiencies （Fv/Fm） and actual photochemical efficiency （60PSU） in the leaves of P. opulifolius were extent of decrease during the than in P. amurensis. In significantly higher, and the flooding process was smaller addition, the non-chemical quenching （NPQ） in the leaves of P. opulifolius significandy increased from the 10th day under flooding stress, while the variation of NPQ in the leaves of P. amurensis was much smaller. This indicates that the leaves of P. opulifolius had not only higher PSII photochemical activity, but also improved tolerance to flooding stress, which may be caused by its ability to dissipate excess excitation energy by starting NPQ. At the 16th day under flooding stress, the PLABS significantly decreased with greater extent of decrease than Fv/Fm in the leaves of both Physocarpus, but the decreasing extent of PIABS in P. opulifolius was significantly smaller than in P. amurensis. In the 16th day under flooding stress, the fluorescence at J and I point （VJ and V1） in P. amurensis were significantly higher, and the extent of increase in VJ was greater than V1. However, the variations of VJ and V1 in the leaves of P. opulifolius were smaller, suggesting that the damage sites of flooding stress to PSII in the leaves of P. amurensis were mainly located in the electron transport process from QA at the PSII receptor side to QB- Flooding stress reduced the proportion （φEo） of luminous energy absorbed by the PSII reaction center for the electron transport following Q2, while the maximum quantum yield （φDo） of non-photochemical quenching increased. However, the TRo/RC and ETo/RC in the leaves of P. amurensis decreased accompanied by a dramatic increase of energy （DIo/RC） from the dissipation in the reaction center. This further indicated that the function of the PSII reaction center in the leaves of P. amurensis was significantly lower than in P. opulifolius.展开更多
基金supported by the National Natural Science Foundation of China(No.31500323)
文摘We applied under pot-culture conditions and the double-casing pot method to study the characteristics of photosynthetic gas exchange and chlorophyll fluorescence in the leaves of Physocarpus amurensis Maxim （PA） and Physocarpus opulifolius under flooding stress. Our results indicate a significantly higher flooding tolerance of P. opulifolius compared to P. amurensis. Especially in P. amurensis, the limitation of non-stomatal factors played a major role in the advanced stages of flooding stress, observed as a rapid increase of the intercellular C02 con- centration （Ci） and a decrease of the stomatal limitation value （Ls）. The maximal PSII photochemical efficiencies （Fv/Fm） and actual photochemical efficiency （60PSU） in the leaves of P. opulifolius were extent of decrease during the than in P. amurensis. In significantly higher, and the flooding process was smaller addition, the non-chemical quenching （NPQ） in the leaves of P. opulifolius significandy increased from the 10th day under flooding stress, while the variation of NPQ in the leaves of P. amurensis was much smaller. This indicates that the leaves of P. opulifolius had not only higher PSII photochemical activity, but also improved tolerance to flooding stress, which may be caused by its ability to dissipate excess excitation energy by starting NPQ. At the 16th day under flooding stress, the PLABS significantly decreased with greater extent of decrease than Fv/Fm in the leaves of both Physocarpus, but the decreasing extent of PIABS in P. opulifolius was significantly smaller than in P. amurensis. In the 16th day under flooding stress, the fluorescence at J and I point （VJ and V1） in P. amurensis were significantly higher, and the extent of increase in VJ was greater than V1. However, the variations of VJ and V1 in the leaves of P. opulifolius were smaller, suggesting that the damage sites of flooding stress to PSII in the leaves of P. amurensis were mainly located in the electron transport process from QA at the PSII receptor side to QB- Flooding stress reduced the proportion （φEo） of luminous energy absorbed by the PSII reaction center for the electron transport following Q2, while the maximum quantum yield （φDo） of non-photochemical quenching increased. However, the TRo/RC and ETo/RC in the leaves of P. amurensis decreased accompanied by a dramatic increase of energy （DIo/RC） from the dissipation in the reaction center. This further indicated that the function of the PSII reaction center in the leaves of P. amurensis was significantly lower than in P. opulifolius.
