Growth and Physiology of Two Psammophytes to Precipitation Manipulation in Horqin Sandy Land, Eastern China.

Juanli Chen,Yongqing Luo,Rui Zhang,Xueyong Zhao,Yayong Luo,Yaqiu Zhang,Xinping Liu,Zhaoquan He

doi:10.3390/plants8070244

Abstract

The availability of water is the critical factor driving plant growth, physiological responses, population and community succession in arid and semiarid regions, thus a precipitation addition-reduction platform with five experimental treatments, was established to explore the growth and physiology of two psammophytes (also known as psammophiles) to precipitation manipulation in Horqin Sandy Land. Changes in coverage and density were measured, and antioxidant enzymes and osmoregulatory substances in both of the studied species were determined. Investigation results showed that the average vegetation coverage increased with an increasing precipitation, and reached a maximum in July. Under the −60% precipitation treatment, Tribulus terrestris accounted for a large proportion of the area, but Bassia dasyphylla was the dominant species in the +60% treatment. T. terrestris was found to have higher a drought stress resistance than B. dasyphylla. From days 4 to 7 after rainfall, B. dasyphylla under precipitation reduction showed obvious water stress. The malondialdehyde (MDA) content of B. dasyphylla was higher than that of T. terrestris, but that of B. dasyphylla had the lower relative water content (RWC). The MDA content in the precipitation reduction treatments of the two studied species was higher than that in the precipitation addition treatments from days 4 to 10. Peroxidase (POD) and superoxide dismutase (SOD) activity and the soluble proteins and free proline content of T. terrestris were higher than those of B. dasyphylla. The free proline content of T. terrestris and B. dasyphylla increased with increasing drought stress. Our data illustrated that T. terrestris had a higher drought stress resistance than B. dasyphylla, which was correlated with the augmentation of some antioxidant enzymes and osmoregulatory substance. The adaptive mechanism provides solid physiological support for an understanding of psammophyte adaptation to drought stress, and of community succession or species manipulation for desertified land restoration.

Highlights

Water is a key driving factor in arid and semi-arid sand ecosystems
The results show that osmoregulatory substances increase under drought stress, and moderate drought induces an increase in antioxidant enzyme activity, but severe drought damages the antioxidant enzyme system
After plants germinate in May, later precipitation significantly affects the growth of the vegetation, which is presented in vegetation coverage and density

Summary

Introduction

Water is a key driving factor in arid and semi-arid sand ecosystems. Plant growth and physiological processes are closely correlated with water availability. Plants 2019, 8, 244 of water in arid and semi-arid sand areas, and is a main constraint on the formation and development of a psammophyte community [1]. With the intensification of global climate change, rainfall events characterized by long intervals and high single rainfall amounts will increase. It is widely accepted that climate variation has caused changes in vegetation distribution patterns and productivity [2]. Plant physiological features, such as photosynthesis and transpiration, antioxidant enzymes and osmoregulatory substances, are affected by climate variation [3,4]. The responses of the above physiological features influence plant community dynamics, such as degradation, restoration and succession

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