Photosynthetica 2015, 53(4):585-596 | DOI: 10.1007/s11099-015-0148-8

Girdling-induced Alhagi sparsifolia senescence and chlorophyll fluorescence changes

G. L. Tang^1,2,3,4, X. Y. Li^1,2,3,*, L. S. Lin^1,2,3, F. J. Zeng^1,2,3, Z. Y. Gu⁵

¹ State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China

² Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Xinjiang, China

³ Key Laboratory of Biogeography and Bioresource in Arid Zone, Chinese Academy of Sciences, Urumqi, China

⁴ University of the Chinese Academy of Sciences, Beijing, China

⁵ Xinjiang Key Laboratory of Soil and Plant Ecological Processes, College of Grassland and Environmental Sciences, Xinjiang Agricultural University, Urumqi, China

Senescence constitutes the final stage of a plant organ and tissue development and is a subject to gene control and strict regulation. By the late growing season, when Alhagi sparsifolia entered the natural senescence period, a girdling treatment was carried out on the phloem to increase the sugar content in leaves and to investigate carbohydrate-induced leaf senescence. After the semi-girdling and full-girdling treatment, organic matter could not leave leaves due to the destruction of sieve tubes. This led to constantly increasing sugar contents in leaves. Girdling was shown to greatly accelerate the senescence of plants. In girdled leaves, chlorophyll (Chl) a, Chl b, carotenoids (Car), and both ratios of Chl a/b and Chl/Car were significantly reduced. On the donor side of PSII, the oxygen-evolving complex was inhibited under high concentrations of carbohydrates, which was manifested as the emergence of the K phase in fluorescence kinetic curves. On the acceptor side of PSII, the high carbohydrate content also led to the disruption of electron transport and reduced light-use efficiency, which was manifested as a reduction in numerous fluorescence parameters. We believe that the emergence and development of plant senescence was not necessarily induced by the high content of carbohydrates, because even a decrease in the carbohydrate concentration could not stop the senescence process. Although the high content of carbohydrates in plants could induce plant senescence, this kind of senescence was likely a pathological process, including degradations of physiological functions.

Keywords: carbon; nutrient cycling; photosynthetic apparatus; photosynthetic pigment; reactive oxygen; stress

Received: August 20, 2014; Accepted: March 2, 2015; Published: December 1, 2015Show citation