Solid-state NMR Spectroscopic Analysis of Sweet Cherry Leaves under Different Cultivation Patterns

Abstract

Solid-state 1H-NMR and 13C-NMR spectroscopy were used to investigate the chemical components of sweet cherry tree leaves under rain-shelter cultivation (RS) and open-field cultivation (CK). The 1H-NMR spectral chemical shifts of RS and CK showed differences in height and integral value. The δ 1–3, δ 3–4, δ 4–6, and δ 6–10 regions were attributed to the hydrogen signals of aliphatic compounds, unsaturated carbohydrate compounds, and aromatic compounds, respectively. Among the four regions, the percentage of signal strength and the integral value of hydrogen signals of RS and CK were 34.25% and 28.34%, 11.64% and 12.26%, 26.71% and 31.06%, 27.4% and 28.34%, respectively. The 13C-NMR results showed that the CK sample had slightly stronger spectral lines and contained slightly more carbon atoms than the RS sample. Sweet cherry leaves contain aromatic and carboxyl carbons, mainly from carboxylic acids, esters, and amides. The alkyl carbons exhibited the lowest ratio, whereas the alkyl and alkoxy carbons were mainly derived from carbohydrates (cellulose, polysaccharides).