Effects of Root Cutting on Morphological Characteristics and Endogenous Hormone Levels of Quercus variabilis Seedlings

The objective of this study was to investigate the effects of root cutting stress on the dynamic changes of endogenous hormone content and growth characteristics of Quercus variabilis roots, and to explore the physiological role of endogenous hormones in regulating root-crown interactions in the short term. The morphological characteristics and endogenous hormone contents of normal roots (no root cutting, CK) and cut roots (cut by 1/3 of the length of the main root, RP) were determined by liquid chromatography, which was combined with mass spectrometry at different levels of different developmental stages. The results showed that the root growth indexes and root endogenous hormones in the RP group were superior to those in the CK group. Through comprehensive analysis of endogenous hormones, it was found that the crosstalk of IAA, JA, ABA and SA could activate the root growth defense. After the root cutting treatment, the root growth of Quercus variabilis seedlings could compensate for the inhibition of taproot growth by promoting lateral root growth. The growth and development of compensatory lateral roots contribute to the increase the total root length of plants, thus promoting the absorption of water and nutrients. It is speculated that plant hormones may be the key factors affecting their development, but this is not only related to the content of a single hormone, but more importantly, it is the interaction between various hormones.