Young Tissues with Weak Water Potential Adjustment Capacity of Desert Shrubs are More Sensitive to Drought
As drought tolerance traits, water potential adjustment capacity is generally used to characterize drought tolerance for plants. Under drought, the embolism produced with the decrease in water potential further spread throughout the xylem hydraulic transport network, which leads to hydraulic failure.
Hydraulic failure is one of the main physiological mechanisms of tree mortality by drought. Frequent global change-type droughts triggered widespread withering and death of woody plants in recent years, which had severe effects on patterns and processes of ecosystems.
For the desert species, water is a main driving force and limiting factor for growth and survival. However, the water potential adjustment capacity and water-sensitivity at the tissue level among shrub species remains unclear.
In a study published in Science of the Total Environment, researchers from the Northwest Institute of Eco-Environment and Resources (NIEER) of the Chinese Academy of Sciences (CAS) investigated the water potential adjustment capacity and sensitivity of different tissues in two desert shrubs.
They evaluated water potential adjustment capacity and water-sensitivity of different tissues in Artemisia ordosica and Caragana korshinskii through calculating the water relation parameters from pressure-volume (P-V) curves.
Results indicated that the sensitivity coefficients, -1/β and -1/b, were gradually decreased with increasing degree of lignification in A. ordosica and C. korshinskii, that is, younger tissues with low lignification are more sensitive to water deficit.
Additionally, the results also suggested that younger tissues have stronger turgor adjustment capacity compared to osmotic adjustment capacity, and they are more easily lose water during times of decreased water potential because of higher cell wall elasticity and weaker water storage capacity.
This study provided critical insight into the water physiological mechanism or sensitivity of species to drought.
Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China