Chin J Plant Ecol ›› 2023, Vol. 47 ›› Issue (10): 1407-1421.DOI: 10.17521/cjpe.2022.0276

• Research Articles • Previous Articles     Next Articles

Hydraulic traits adjustments and nonstructural carbohydrate dynamics of Haloxylon ammodendron under drought stress

CHEN Tu-Qiang, XU Gui-Qing(), LIU Shen-Si, LI Yan   

  1. State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi 830011, China;National Field Scientific Observation and Research Station of Desert Ecology, Chinese Academy of Sciences, Fukang, Xinjiang 831505, China; and University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2022-07-04 Accepted:2023-03-13 Online:2023-10-20 Published:2023-11-23
  • Contact: * (
  • Supported by:
    National Natural Science Foundation of China(32171874);Xinjiang Uygur Autonomous Region Tianshan Youth Program Project(2020Q025)


Aims Haloxylon ammodendron is the major dominated species in the Gurbantünggüt Desert, which plays a key role in ecosystem services: such as biodiversity conservation and prevention of dryland degradation. Frequent droughts have a significant impact on the survival of H. ammodendron, thus understanding the drought resistant strategies of H. ammodendron is essential for the sustainability and stability of desert ecosystems. Robust hydraulic system and carbon balance are important parts of the drought resistance mechanism, but the hydraulic threshold for survival of H. ammodendron under drought stress are still unquantified.

Methods We set up a control group and a drought treatment group for adult H. ammodendron, and determined the water status of assimilation twigs, the loss rate of xylem hydraulic conductivity in branches, gas exchange characteristics, nonstructural carbohydrate (NSC) contents and morphological characteristics at upper, lower and middle branches of H. ammodendron. We used one-way ANOVA for each trait among different treatments and heights, linear regression for stomatal sensitivity and principal component analysis for drought resistance of H. ammodendron, respectively.

Important findings (1) The predawn and midday water potential of assimilation twig, assimilation twig water content and branch water content of H. ammodendron decreased under drought stress, but did not affected by the increase of height; P50 and P88 (xylem tension causing 50% and 88% loss of maximum hydraulic conductivity) did not change significantly under drought and with increasing height, and the mean value of P50 was -4.12 MPa and P88 was -7.10 MPa for each height and treatment groups, while the hydraulic safety margin was significantly reduced under drought. (2) The stomatal opening of H. ammodendron was not sensitive to drought stress, and thus drought stress and branch height increase did not significantly affect net photosynthetic rate and stomatal conductance in general. (3) The NSC contents of assimilation twigs and branches did not decrease under drought stress or with increasing branch height; the value of NSC contents in the assimilation twigs and branches were 22.11% and 13.10% higher, compared to the control group. (4) The Huber value of H. ammodendron increased by 73.78% in the drought treatment group compared to the control group; the specific leaf area decreased by 14.60% compared to the control group, but there were no significant difference between the two treatment groups. In conclusion, the hydraulic traits of H. ammodendron were significantly affected by drought stress, but not by the increase of branch height, and there was no hydraulic limitation with increasing branch height. Under drought stress, the risk of simultaneous hydraulic failure of the peripheral branches at the crown edge was high, the hydraulic safety margin (difference between midday assimilation twig water potential and P88) was only 40.85% of that of the control group. Due to the low sensitivity of stomata to water stress, the shrub can maintain the capacity of photosynthetic carbon fixation under drought stress, and even slightly increased NSC contents of the assimilation twigs and branches.

Key words: drought stress, drought resistant strategy, hydraulic trait, nonstructural carbohydrate, tree mortality, Haloxylon ammodendron