Effects of drought stress on protective enzyme activity and osmotic regulatory substances in desert plant Haloxylon ammodendron seedlings

We investigated the response mechanisms of different indicators during the gradual aggravation of soil drought using pot experiments and determined the changes in the water content, protective enzyme activity, and osmosis-regulating substances in the leaves of desert plant Haloxylon ammodendron seedlings during natural drought after artificial watering. The results demonstrated the following: 1) The relative water content (RWC) of H. ammodendron leaves decreased with an increase in the number of natural drought days, whereas the relative water deficit (RWD) displayed a fluctuating upward trend. 2) Continuous drought significantly damaged the cell membrane of H. ammodendron leaves, and the relative electrical conductivity (REC) of the leaves gradually increased. However, the accumulation of malondialdehyde (MDA) was insignificant. 3) The contents of soluble sugar (SS), soluble protein (SPC), proline (Pro), and activity of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) displayed different responses to persistent drought. The plants were largely dependent on the synergistic effect of POD, SOD, and Pro to resist cellular damage caused by reduced soil moisture content. Altogether, the findings revealed the relationship between drought resistance physiological indicators of H. ammodendron leaves and soil moisture, providing a physiological and ecological basis for species selection in arid desert areas.