Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 May 16;12(5):444.
doi: 10.3390/metabo12050444.

Differential Metabolic Responses of Lettuce Grown in Soil, Substrate and Hydroponic Cultivation Systems under NH4+/NO3- Application

Affiliations

Differential Metabolic Responses of Lettuce Grown in Soil, Substrate and Hydroponic Cultivation Systems under NH4+/NO3- Application

Muhammad Khalid Hameed et al. Metabolites. .

Abstract

Nitrogen (N) is an essential element for plant growth and development. The application of a balanced and optimal amount of N is required for sustainable plant yield. For this, different N sources and forms are used, that including ammonium (NH4+) and nitrate (NO3-). These are the main sources for N uptake by plants where NH4+/NO3- ratios have a significant effect on the biomass, quality and metabolites composition of lettuce grown in soil, substrate and hydroponic cultivation systems. A limited supply of N resulted in the reduction in the biomass, quality and overall yield of lettuce. Additionally, different types of metabolites were produced with varying concentrations of N sources and can be used as metabolic markers to improve the N use efficiency. To investigate the differential metabolic activity, we planted lettuce with different NH4+/NO3- ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and a control (no additional N applied) in soil, substrate and hydroponic cultivation systems. The results revealed that the 25% NH4+/75% NO3- ratio increased the relative chlorophyll contents as well as the biomass of lettuce in all cultivation systems. However, lettuce grown in the hydroponic cultivation system showed the best results. The concentration of essential amino acids including alanine, valine, leucine, lysine, proline and serine increased in soil and hydroponically grown lettuce treated with the 25% NH4+/75% NO3- ratio. The taste and quality-related compounds in lettuce showed maximum relative abundance with the 25% NH4+/75% NO3- ratio, except ascorbate (grown in soil) and lactupicrin (grown in substrate), which showed maximum relative abundance in the 50% NH4+/50% NO3- ratio and control treatments, respectively. Moreover, 1-O-caffeoylglucose, 1,3-dicaffeoylquinic acid, aesculetin and quercetin-3-galactoside were increased by the application of the 100% NH4+/0% NO3- ratio in soil-grown lettuce. The 25% NH4+/75% NO3- ratio was more suitable in the hydroponic cultivation system to obtain increased lettuce biomass. The metabolic profiling of lettuce showed different behaviors when applying different NH4+/NO3- ratios. Therefore, the majority of the parameters were largely influenced by the 25% NH4+/75% NO3- ratio, which resulted in the hyper-accumulation of health-promoting compounds in lettuce. In conclusion, the optimal N applications improve the quality of lettuce grown in soil, substrate and hydroponic cultivation systems which ultimately boost the nutritional value of lettuce.

Keywords: ammonium; lettuce; metabolites; nitrate; nitrogen.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Effect of various applied NH4+/NO3 ratios on the relative chlorophyll contents of lettuce grown in soil, substrate and hydroponic cultivation systems. Note- The means (n = 4) ± standard errors are shown in the data. Different letters (a–f) show significant difference (p = 0.01) among applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) in lettuce grown in soil, substrate and hydroponic cultivation systems.
Figure 2
Figure 2
Effect of various applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) in different intervals of time on shoot fresh biomass of lettuce grown in soil, substrate and hydroponic cultivation systems. Note-The means (n = 4) ± standard errors are shown in the data.
Figure 3
Figure 3
Effect of various applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) on taste and quality-related compounds in lettuce grown in soil, substrate and hydroponic cultivation systems. Note- The means (n = 4) ± standard errors are shown in the data. Different letters (a–c) show significant difference (p = 0.01) among applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control in lettuce grown in soil, substrate and hydroponic cultivation systems.
Figure 4
Figure 4
Effect of various applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) on sugar compounds in lettuce grown in soil, substrate and hydroponic cultivation systems. Note- The means (n = 4) ± standard errors are shown in the data. Different letters (a–d) show significant difference (p = 0.01) among applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control in lettuce grown in soil, substrate and hydroponic cultivation systems.
Figure 5
Figure 5
Effect of various applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) on different amino acid contents of lettuce grown in soil, substrate and hydroponic cultivation systems. Note- The means (n = 4) ± standard errors are shown in the data. Different letters (a–d) show significant difference (p = 0.02) among applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control in lettuce grown in soil, substrate and hydroponic cultivation systems.
Figure 6
Figure 6
Effect of various applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) on different polyphenolic compounds in lettuce grown in soil, substrate and hydroponic cultivation systems. Note- The means (n = 4) ± standard errors are shown in the data. Different letters (a–f) show significant difference (p = 0.001) among applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control in lettuce grown in soil, substrate and hydroponic cultivation systems.
Figure 7
Figure 7
PCA and PLS-DA analysis of the metabolomic profile of lettuce with different applied NH4+/ NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) in soil, substrate and hydroponic cultivation systems by GC-MS analysis. Note- (AC) represents PCA analysis and (DF) represents PLS-DA analysis of metabolomic profiling of lettuce in soil, substrate and hydroponic cultivation systems by GC-MS analysis. Green color represents NH4+/NO3 (100/0%), blue color represents NH4+/NO3 (75/25%), red color represents NH4+/NO3 (50/50%), yellow color represents NH4+/NO3 (25/75%), sky-blue color represents NH4+/NO3 (0/100%) and purple color represents control.
Figure 8
Figure 8
PCA and PLS-DA analysis of the metabolomic profile of lettuce with different applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) in soil, substrate and hydroponic cultivation systems by UPLC VION IMS QTOF-MS/MS analysis. Note- (AC) represents PCA analysis and (DF) represents PLS-DA analysis of metabolomic profiling of lettuce in soil, substrate and hydroponic cultivation system by UPLC VION IMS QTOF-MS/MS analysis. Green color represents NH4+/NO3 (100/0%), blue color represents NH4+/NO3 (75/25%), red color represents NH4+/NO3 (50/50%), yellow color represents NH4+/NO3 (25/75%), sky-blue color represents NH4+/NO3 (0/100%) and purple color represents control.
Figure 9
Figure 9
PLS-DA analysis of whole metabolomic profiling of lettuce through GC-MS and UPLC VION IMS QTOF-MS/MS analysis by combining means of all different applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) in soil, substrate and hydroponic cultivation systems. Note- (A) PLS-DA analysis using GC-MS in which green color represents hydroponically grown lettuce, red color represents soil-grown lettuce and yellow color represents substrate-grown lettuce; (B) PLS-DA analysis using UPLC VION IMS QTOF-MS/MS in which blue color represents hydroponically grown lettuce, red color represents soil-grown lettuce and yellow color represents substrate-grown lettuce.
Figure 10
Figure 10
Venn diagrams of lettuce metabolites in soil, substrate and hydroponic cultivation systems using GC-MS and UPLC VION IMS QTOF-MS/MS analysis. Note- (A) Similar and different metabolites in metabolomic profiling of lettuce in soil, substrate and hydroponic cultivation systems using GC-MS analysis; (B) similar and different metabolites in metabolomic profiles of lettuce in soil, substrate and hydroponic cultivation systems using UPLC VION IMS QTOF-MS/MS analysis.
Figure 11
Figure 11
Heat map of different metabolites in soil-, substrate- and hydroponically grown lettuce. Note- Left-side (A) shows up- and down-regulation of metabolites in metabolomic profiles of lettuce in soil, substrate and hydroponic cultivation systems by combining means of all different applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:75 and 0:100%) and control (no additional N applied) in hydroponic, soil, and substrate cultivation systems. Right-side (B) shows variation in up- and down-regulation of metabolites in metabolomic profiles of lettuce by various applied NH4+/NO3 ratios (100:0, 75:25, 50:50, 25:7 and, 0:100%) and control (no additional N applied) in hydroponic, soil, and substrate cultivation systems. Red color represents soil-grown lettuce metabolites, green color represents substrate-grown lettuce metabolites and blue color represents hydroponically grown lettuce metabolites.

References

    1. Lin Y.-L., Tsay Y.-F. Influence of differing nitrate and nitrogen availability on flowering control in Arabidopsis. J. Exp. Bot. 2017;68:2603–2609. doi: 10.1093/jxb/erx053. - DOI - PubMed
    1. Zhang X., Zou T., Lassaletta L., Mueller N.D., Tubiello F.N., Lisk M.D., Lu C., Conant R.T., Dorich C.D., Gerber J., et al. Quantification of global and national nitrogen budgets for crop production. Nat. Food. 2021;2:529–540. doi: 10.1038/s43016-021-00318-5. - DOI - PubMed
    1. Li D., Liu J., Zong J., Guo H., Li J., Wang J., Wang H., Li L., Chen J. Integration of the metabolome and transcriptome reveals the mechanism of resistance to low nitrogen supply in wild bermudagrass (Cynodon dactylon (L.) Pers.) roots. BMC Plant Biol. 2021;21:480. doi: 10.1186/s12870-021-03259-0. - DOI - PMC - PubMed
    1. Zhou T., Hua Y., Yue C., Huang J., Zhang Z. Physiologic, metabolomic, and genomic investigations reveal distinct glutamine and mannose metabolism responses to ammonium toxicity in allotetraploid rapeseed genotypes. Plant Sci. 2021;310:110963. doi: 10.1016/j.plantsci.2021.110963. - DOI - PubMed
    1. Chowdhury N.B., Schroeder W.L., Sarkar D., Amiour N., Quilleré I., Hirel B., Maranas C.D., Saha R. Dissecting the metabolic reprogramming of maize root under nitrogen-deficient stress conditions. J. Exp. Bot. 2021;73:275–291. doi: 10.1093/jxb/erab435. - DOI - PubMed

LinkOut - more resources