title: Combined effects of girdling and leaf removal on fluorescence characteristic of Alhagi sparsifolia leaf senescence.
abstract: Plant senescence is largely influenced by carbohydrate content. In order to investigate the impact of carbohydrate content on leaf senescence and photosystem II (PSII) during the senescence process, phloem girdling (PG), leaf removal (LR) and a combination of phloem girdling and leaf removal (GR) were performed on Alhagi sparsifolia (Fabaceae) at the end of the growing season. The results showed that during senescence, leaf soluble sugar content, starch content, the energy absorbed by the unit reaction centre (ABS/RC) increased; whereas, leaf photosynthetic rate, photosynthetic pigment content, maximum photochemical efficiency (φPo ) and energy used by the acceptor site in electron transfer (ETo/RC) decreased. The degree of change was PG > GR > CK (control) > LR. The results of the present work implied that phloem girdling (PG) significantly accelerated leaf senescence, and that single leaf removal (LR) slightly delayed leaf senescence; although leaf removal significantly delayed the senescence process on the girdled leaf (GR). Natural or delayed senescence only slightly inhibited the acceptor site of PSII and did not damage the donor site of PSII. On the other hand, induced senescence not only damaged the donor site of PSII (e.g. oxygen-evolving complex), but also significantly inhibited the acceptor site of PSII. In addition, leaf senescence led to an increase in the energy absorbed by the unit reaction centre (ABS/RC), which subsequently resulted in increasing excitation pressure in the reaction centre (DIo/RC), as well as additional saved Car for absorbing residual light energy and quenching reactive oxygen species during senescence.
authors: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China.|Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Cele, Xinjiang, China.|Key Laboratory of Biogeography and Bioresource in Arid Zone, Chinese Academy of Sciences, Urumqi, China.|University of the Chinese Academy of Sciences, Beijing, China.
authors: G
authors: G
authors: Tang
authors: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China.|Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Cele, Xinjiang, China.|Key Laboratory of Biogeography and Bioresource in Arid Zone, Chinese Academy of Sciences, Urumqi, China.
authors: X
authors: X
authors: Li
authors: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China.|Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Cele, Xinjiang, China.|Key Laboratory of Biogeography and Bioresource in Arid Zone, Chinese Academy of Sciences, Urumqi, China.
authors: L
authors: L
authors: Lin
authors: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China.|Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Cele, Xinjiang, China.|Key Laboratory of Biogeography and Bioresource in Arid Zone, Chinese Academy of Sciences, Urumqi, China.|University of the Chinese Academy of Sciences, Beijing, China.
authors: H
authors: H
authors: Guo
authors: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China.|Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Cele, Xinjiang, China.|Key Laboratory of Biogeography and Bioresource in Arid Zone, Chinese Academy of Sciences, Urumqi, China.
authors: L
authors: L
authors: Li
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport; D007887:Fabaceae / Q000502:physiology*; D005453:Fluorescence; D052585:Phloem / Q000502:physiology; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000502:physiology*; D012621:Seasons
chemical_list: D002241:Carbohydrates; D045332:Photosystem II Protein Complex; D002734:Chlorophyll
keywords: Alhagi sparsifolia; carbohydrate content; chlorophyll fluorescence; leaf removal; phloem girdling; senescence