Phosphorous Supplementation Alleviates Drought-Induced Physio-Biochemical Damages in Calligonum mongolicum

<i>Calligonum mongolicum</i> is a phreatophyte playing an important role in sand dune fixation, but little is known about its responses to drought and P fertilization. In the present study, we performed a pot experiment to investigate the effects of P fertilization under drought or well-watered conditions on multiple morpho-physio-biochemical attributes of <i>C. mongolicum</i> seedlings. Drought stress leads to a higher production of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), leading to impaired growth and metabolism. However, <i>C. mongolicum</i> exhibited effective drought tolerance strategies, including a higher accumulation of soluble sugars, starch, soluble protein, proline, and significantly higheractivities of peroxidase (POD) and catalase (CAT) enzymes. P fertilization increased the productivity of drought-stressed seedlings by increasing their growth, assimilative shoots relative water content, photosynthetic pigments, osmolytes accumulation, mineral nutrition, N assimilation, and reduced lipid peroxidation. Our findings suggest the presence of soil high P depletion and <i>C. mongolicum</i> high P requirements during the initial growth stage. Thus, P can be utilized as a fertilizer to enhance the growth and productivity of <i>Calligonum</i> vegetation and to reduce the fragility of the hyper-arid desert of Taklamakan in the context of future climate change.