Background: Although nitrogen (N) is a critical nutrient for the growth of Panax ginseng, its excessive application often induces physiological disorders. To establish an effective fertilization strategy, in this study, we investigated how periodic N topdressing affects root hypertrophy and cell wall-related gene expression.Methods and Results: We performed a 26-week pot experiment on 2-year-old ginseng plants treated with various urea concentrations (0, 2.5, 5.0, and 10.0 ㎏/10 a). In addition, we performed a field trial on 3-year-old ginseng plants from July to October (12 weeks) to compare split application frequencies. In the pot experiment, the 10.0 ㎏/10 a N treatment delayed leaf senescence and increased root weight by 28.5% compared to the control. In the field, split application (i.e., six times at 2-week intervals) was more efficient than less frequent application, increasing the yield and root hardness by 23.7% and > 10%. Real-time qPCR analysis performed using samples from the pot experiment revealed that N treatment rapidly upregulated EXPB3 and CESA6 within 24 h, indicating activated cell wall loosening and secondary wall synthesis.Conclusions: Periodic N topdressing promoted secondary growth and improved root quality in P. ginseng by activating cell wall-related genes without causing salt injury. Split application of urea has been suggested as an optimal nutrient management strategy for maximizing ginseng yield and quality.
Kim et al. (Sat,) studied this question.
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