Response of Root Growth and Root Border Cell Characteristics of Hemerocallis fulva to NaCl Stress

Taking three Hemerocallis cultivars ('Jingzhouhua', 'Qingchong', 'Changzuizihua') with different salt tolerance as materials, the effects of 0-200 mmol/L NaCl on root morphology and Root Border Cell (RBC) characteristics were investigated using hydroponic and root suspension culture methods and one-way analysis of variance (ANOVA). The results showed that the root morphology indicators and activity of the high-salt-tolerant 'Jingzhouhua' decreased less than those of the medium-salt-tolerant 'Qingchong' and salt-sensitive 'Changzuizihua'. As the salt concentration increased, the number and viability of RBCs in these three cultivars decreased in the order of 'Jingzhouhua' < 'Qingchong' < 'Changzuizihua'. NaCl stress increased the apoptotic rate of RBCs and the thickness of the mucilage layer; 'Jingzhouhua' had the lowest apoptosis rate and the thickest mucilage layer, followed by 'Qingchong' and 'Changzuizihua'. Under NaCl stress, maintaining a high number of RBCs, survival rate, and mucus layer thickness helps stabilize the root function and morphology of 'Jingzhouhua', which is the reason for its strong salt tolerance.