Effect of different nitrogen levels on yield and quality of Pogostemon cablin

To investigate the effect of different nitrogen levels on yield and quality of Pogostemon cablin, a sand culture experiment is used to explore changes of the patchouli nitrogen nutrition, growth traits, yield and volatile oil content and quality under 3, 6, 12, 18 and 24 mmol/L nitrogen levels (N1, N2, N3, N4, N5). The results show that the patchouli growth traits parameters, nitrogen nutrition, plant fresh and dry weight, volatile oil content are improved with the increase of the nitrogen level, however, the stem and leaf oil contents are decreased. In patchouli stem volatile oil, 12 ingredients in N1 and N2 are significantly higher than those in N4 and N5. The contents of -patchoulene, -guaiene, nerolidol, -guaiene, trans-caryophyllene, patchouli alcohol and pogostone are the highest in the N1 treatment, while the contents of seychellene, -patchoulene, -guaiene, -elemene and iso-caryophyllene are the highest in the N2 treatment. In the leaf oil, except for -patchoulene, the contents of other bioactive compounds of N1 and N2 are significantly higher than those of N4 and N5. The contents of -patchoulene, -guaiene, -guaiene, -cubebene, iso-caryophyllene, -guaiene, trans-caryophyllene, patchouli alcohol and pogostone are the highest in the N1 treatment, while the contents of seychellene, -patchoulene and -elemene are the highest in the N2 treatment. The 12 ingredients of the patchouli stems and leaf volatile oil have no significant differences between N1 and N2 or N4 and N5. In general, the increase of the nitrogen level is conducive to increasing the volatile oil content, but reducing the oil content.