Morphological and physiological responses of Heteropogon contortus to drought stress in a dry-hot valley

Xue-Mei Wang; Li Zhao; Bang-Guo Yan; Liang-Tao Shi; Gang-Cai Liu; Yu-Xiao He

doi:10.1186/s40529-016-0131-0

Morphological and physiological responses of Heteropogon contortus to drought stress in a dry-hot valley

Bot Stud. 2016 Dec;57(1):17. doi: 10.1186/s40529-016-0131-0. Epub 2016 Aug 8.

Authors

Xue-Mei Wang^{1

2}, Li Zhao³, Bang-Guo Yan^{1

2}, Liang-Tao Shi⁴, Gang-Cai Liu¹, Yu-Xiao He⁵

Affiliations

¹ Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences and Ministry of Water Resources, Chengdu, 610041, China.
² University of Chinese Academy of Sciences, Beijing, 100049, China.
³ College of Environment and Resource Science, Southwest University of Science and Technology, Mianyang, 621010, China.
⁴ Institute of Tropical Eco-agricultural Sciences, Yunnan Academy of Agricultural Sciences, Yuanmou, 651300, Yunnan Province, China.
⁵ Institute of Resources and Environment, He'nan Polytechnic University, Jiaozuo, 454000, He'nan, China. heyuxiao@hpu.edu.cn.

Abstract

Background: Heteropogon contortus is a valuable pasture species that is widely used for vegetation restoration in dry-hot valleys of China. However, to date, its morphological and physiological responses to drought, and the underlying mechanisms are not well understood. This study was aimed to investigate the morphological and physiological changes of H. contortus under drought stress during the dry-hot season. Heteropogon contortus was planted in pots and subjected to four levels of soil water treatments: above 85 % (control), 70-75 % (light stress), 55-60 % (moderate stress) or 35-40 % (severe stress) of field capacity.

Results: Within the total stress period (0-29 days), H. contortus grew rapidly in the light stress, whereas severe stress had a negative impact on growth. Aboveground biomass decreased together with increasing drought stress, whereas root biomass increased. Consequently, the root/shoot ratio of the severe stress treatment increased by 80 % compared to that of the control treatment. The ratio of bound water/free water (BW/FW) was the most sensitive parameter to drought and showed a value under severe stress that was 152.83 % more than that in the control treatment. Although leaf water potential (LWP) and leaf relative water content (RWC) decreased with progressive water stress, H. contortus managed to maintain a relatively high RWC (nearly 70 %) in the severe stress condition. We also detected a significant reduction (below 0.6) in the ratio of variable fluorescence/maximum fluorescence (Fv/Fm) in the severe stress treatment.

Conclusions: Our results show that H. contortus adapts to drought mainly by avoidance mechanisms, and its morphological and physiological characteristics are inhibited under severe stress, but can recover at a certain time after re-watering. These findings might help limited water resources to be fully used for vegetation management in the studied region.

Keywords: Biomass allocation; Chlorophyll fluorescence; Drought stress; Heteropogon contortus; Leaf water potential; Relative water content.