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Updated: 02-01-16 | ||||
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EFFECTS OF PROGRESSIVE SOIL WATER DEFICIT ON GROWTH, AND PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES OF POPULUS EUPHRATICA IN ARID AREA: A CASE STUDY IN CHINA
YUHAI YANG*, YANING CHEN, WEIHONG LI AND CHENGGANG ZHU
State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China *Corresponding author’s e-mail: yangyh@ms.xjb.ac.cn; Phone (fax) numbers: +86 9917823160
Abstract: The aim of this study was to investigate the responses of Populus euphratica seedlings under a short-term soil water deficit. To mimic natural conditions in which drought stress develops gradually, stress was imposed by subjecting plants to a gradual decrease of soil water content for a period of 21 d. We studied growth, physiological and biochemical responses to progressive soil water deficit of potted Populus euphratica seedlings at outdoors. Results showed that, in 6 d of water withholding, the soil moisture content decreased to a slight drought stress level, and it reached a severe drought stress level after 15 d of water withholding in July. In the process of soil water declining from saturated to severe drought levels, the increasing soil water deficit resulted in decreases in the height, stem base diameter, number of lateral branches. Leaf predawn water potential decreased after 15 d of withholding irrigation. After 21 d of withholding irrigation, actual photochemical efficiency of photosystem II (PSII) in light-adapted leaves and photochemical quenching coefficient decreased, respectively; the peroxidase activity, the content of chlorophyll a and chlorophyll b decreased. There were no significant changes in proline, malondialdehyde content, chlorophyll a/b value and superoxide dismutase activity.
Key words: Water, Response, Seedling, Arid.
Abbreviations: AK: available potassium; AN: available nitrogen; AP: available phosphorus; Chl a: chlorophyll a; Chl b: chlorophyll b; CK: well-watered control treatment; D: water deficit treatment; Fm′: maximum fluorescence yield of the light-adapted state; Fo: initial fluorescence yield in the dark; Fo′: initial fluorescence in the light; Fm: maximum fluorescence in the dark; Fs: steady state fluorescence of specific time; gs: leaf stomatal conductance; MDA: malondialdehyde; OM: organic matter; PAR: photosynthetically active radiation; POD: peroxidase; Pro: proline; PSII: photosystem II; ΦPSII: actual photochemical efficiency of PSII in light-adapted leaves; qP: photochemical quenching coefficient; SOD: superoxide dismutase; TK: total potassium; TN: total nitrogen; TP: total phosphorus; ψp: leaf predawn water potential.
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