Effect of high desert surface layer temperature stress on Haloxylon ammodendron (C.A. Mey.) Bunge

Haloxylon ammodendron (Chenopodiaceae) is a dominant shrubby or sub-arboreal perennial. During the torrid and arid summer, annual assimilative branches of H. ammodendron are often observed slow growing (even ceasing growth) and gradually turning in color from green to brilliant yellow, even with some drying up and falling off. The pivotal factor causing this phenomenon is still unknown. Here we report that it is the high desert surface layer (0–5 cm) temperature (DSLT) that causes H. ammodendron plants to display this phenomenon. Damage is caused by high DSLT around the stem basal part of H. ammodendron plants, with stress threshold value being 55 °C. Based on the color changes of the annual assimilative branches, damage responses of H. ammodendron could be broadly divided into three degrees of mild, moderate and high damage that visually can be detected. DSLT stress also destroys the redox homeostasis in H. ammodendron plants, bringing about physiological damages. Since high DSLT is one of the inherent factors of desert habitat conditions, our results suggest that it will have importance to investigate the direct effect of high DSLT stress also on other desert plants.