Response of growth characteristics and endogenous hormones of Sophora davidii to low-phosphorus stress

Dynamic changes in growth characteristics and endogenous hormone contents in the leaves and roots of Sophora davidii seedlings under low-phosphorus stress were studied to provide a reference for further study of the internal regulatory mechanism of the response strategy of this species to low-phosphorus stress. Normal phosphorus (0.5 mmol KH 2 PO 4 , NP) and low-phosphorus (0.005 mmol KH 2 PO 4 , LP) levels and different treatment times were applied to study growth characteristics, phosphorus utilization and hormone contents in the leaves and roots of potted Sophora davidii by tissue culture and sand culture. The results first showed that compared with NP, LP significantly decreased the plant height, leaf length, leaf width, leaf area, leaf perimeter and root–shoot ratio by 20.10%, 21.08%, 22.73%, 51.33%, 24.94% and 18.92%, respectively. LP decreased the total root length and root dry weight, and increased the root surface area, average root diameter, root tip number, root volume and dry weight of the aerial part on day 9, but these effects were not significant. Second, compared with NP, LP significantly decreased P contents in the aerial part and roots and P uptake efficiency in the aerial part and roots on day 9 by 23.33%, 53.89%, 14.04% and 58.06%, respectively. LP significantly increased the P utilization efficiency and leaf acid phosphatase (ACP) activity on day 9 by 82.79% and 84.38%, respectively. LP increased root ACP activity on day 9, but the effect was not significant. Third, compared with NP, LP significantly decreased abscisic acid (ABA), cytokinin (CTK) and strigolactone (SL) contents in leaves by 21.52%, 36.65% and 45.86%, respectively, and significantly increased gibberellin (GA) contents in roots by 28.92% on day 9. LP decreased GA contents in leaves and CTK contents in roots and increased indole-3-acetic acid (IAA) contents in leaves and roots and ABA and SL contents in roots on day 9, but these effects were not significant. Correlation analysis indicated that endogenous hormone contents in Sophora davidii leaves and roots under different treatment conditions had certain correlations with growth characteristics. In conclusion, Sophora davidii can improve its P utilization efficiency by changing growth characteristics and endogenous hormones to enhance its adaptive response to low-phosphorus stress.