Aims Ammonium (NH4+) and nitrate (NO3−) are one of the most important factors in controlled environments that influence plant physiological and phytochemical characteristics. The present study was performed to evaluate the effect of nitrogen forms on phytochemical characteristics in different culture systems, and also to evaluate the effect of nitrogen treatments on the expression of important genes involved in the glycyrrhizic acid (GA) biosynthetic pathway in licorice (Glycyrrhiza glabra L.). Methods In the first experiment, the 10-cm-tall seedlings were transferred to the desired cultivation systems, including (aeroponic, nutrient film technique (NFT), and inert and soil substrate) to evaluate secondary metabolites of licorice under the influence of different nitrogen forms (NO3−, NH4NO3, and NH4+). In the second experiment, three months after root formation of seedlings, various nutritional treatments (nitrogen deficiency, NO3−, NH4NO3, and NH4+) were applied. Samples from the roots and leaves were collected on days 2, 16, and 28 after the nutritional treatment and were transferred to the laboratory for RNA extraction. Results The addition of ammonium significantly increased GA levels, with percentage increases of 66.66%, 49.36%, 50%, and 8.33% observed in aeroponic, NFT, substrate, and soil systems when compared with nitrate treatment. Additionally, liquiritin levels also showed notable increases of 15.79%, 22.37%, 5.68%, and 61.54% in the same systems, respectively. Both GA and liquiritin were present at higher levels in soilless culture systems compared with soil cultivation. Liquiritigenin was not detected in plants fed with ammonium in aeroponic, NFT, and neutral substrate cultivation conditions; however, it was detected in plants fed with ammonium nitrate and the highest amounts were found in nitrate-treated plants. Conclusions The present findings offer a deeper understanding of the physiological and molecular changes of secondary metabolites in licorice when subjected to various nitrogen sources. Finally, it was concluded that hydroponic systems have a suitable potential for high-quality licorice production compared with soil culture systems.

Changes in secondary metabolites and glycyrrhizic acid related gene expression of licorice (Glycyrrhiza glabra L.) exposed to different nitrogen sources under soil and soilless culture systems

期刊论文
发表日期：

2026年5月7日

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Hamid Reza Roosta,
Ahmad Estaji,
Ali Khadivi

摘要

Aims

Ammonium (NH₄⁺) and nitrate (NO₃⁻) are one of the most important factors in controlled environments that influence plant physiological and phytochemical characteristics. The present study was performed to evaluate the effect of nitrogen forms on phytochemical characteristics in different culture systems, and also to evaluate the effect of nitrogen treatments on the expression of important genes involved in the glycyrrhizic acid (GA) biosynthetic pathway in licorice (Glycyrrhiza glabra L.).

Methods

In the first experiment, the 10-cm-tall seedlings were transferred to the desired cultivation systems, including (aeroponic, nutrient film technique (NFT), and inert and soil substrate) to evaluate secondary metabolites of licorice under the influence of different nitrogen forms (NO₃⁻, NH₄NO₃, and NH₄⁺). In the second experiment, three months after root formation of seedlings, various nutritional treatments (nitrogen deficiency, NO₃⁻, NH₄NO₃, and NH₄⁺) were applied. Samples from the roots and leaves were collected on days 2, 16, and 28 after the nutritional treatment and were transferred to the laboratory for RNA extraction.

Results

The addition of ammonium significantly increased GA levels, with percentage increases of 66.66%, 49.36%, 50%, and 8.33% observed in aeroponic, NFT, substrate, and soil systems when compared with nitrate treatment. Additionally, liquiritin levels also showed notable increases of 15.79%, 22.37%, 5.68%, and 61.54% in the same systems, respectively. Both GA and liquiritin were present at higher levels in soilless culture systems compared with soil cultivation. Liquiritigenin was not detected in plants fed with ammonium in aeroponic, NFT, and neutral substrate cultivation conditions; however, it was detected in plants fed with ammonium nitrate and the highest amounts were found in nitrate-treated plants.

Conclusions

The present findings offer a deeper understanding of the physiological and molecular changes of secondary metabolites in licorice when subjected to various nitrogen sources. Finally, it was concluded that hydroponic systems have a suitable potential for high-quality licorice production compared with soil culture systems.