Identification of Active Components in Humic Acids Affecting Tomato Germination

摘要

Humic acids can promote the germination of many vegetable seeds,but the key active components remain unclear.This study utilized nutrient content,cross polarization magic angle spin ¹³C solid magnetic resonance (CPMAS–¹³C–NMR) and ultra-high performance liquid chromatography-mass spectrometry （UHPLC–MS） to characterize the chemical components of humic acids.Tomato seed germination index （GI） was determined with the goal of screening the key active components of humic acids.Humic acids had a significantly higher nutrient content,except for the total nitrogen （TN） and the total phosphorus （TP） contents.Humic acids had a higher content of O–CH₃/NCH,aromatic C–O and carbonyl C compared to weathered coal,with significantly lower anomeric C,aromatic C and O–alkyl C/alkyl C.There were 611 different compounds identified among the test materials using UHPLC–MS.Humic acids also had a significantly higher GI （158.0% and 153.1%） than weathered coal （85.5%）.The organic matter （OM）,TP and available potassium （AK） contents in humic acids were significantly positively correlated with GI,and available phosphorus （AP） was significantly negatively correlated.Among the carbon components,O–CH₃/NCH,aromatic C–O and O–alkyl C/alkyl C were significantly positively correlated with GI,while anomeric C was significantly negatively correlated.Furthermore,among the top 10 positive and five negative correlation compounds,lipids and lipid-like molecules[armexifolin,boviquinone 4,3-methyladipic acid,lxocarpalactone A,monic acid,DG(20:1（11Z）/18:4（6Z,9Z,12Z,15Z）/0:0),and brassinolide]and organic acids and derivatives （N-acetylglutamic acid,8-hydroxy-5,6-octadienoic acid,acetyl-L-tyrosine,and hydroxyprolyl-methionine） in humic acids might be crucial active components for improving tomato seed germination.The results provided direct evidence for the identification of bioactive molecules of humic acids,and a scientific basis for the precise utilization of bioactive molecular components of humic acids in sustainable agricultural development.

关键词

humic acid / cross polarization magic angle spin ¹³C solid magnetic resonance(CPMAS–¹³C–NMR) / ultra-high performance liquid chromatography-mass spectrometry（UHPLC–MS） / germination index（GI） / active component