Agronomic characteristics, objective quantitative, metabolome and transcriptome analysis reveal the influence of fertilization treatments on fresh leaf characteristics and finished tea quality

Fertilization is important for tea garden management and tea flavor improvement; however, the effects of different ratios of organic and chemical fertilizer on fresh tea leaf quality and finished tea flavor remain unclear. Therefore, four fertilization treatments were used to elucidate the underlying mechanisms. Fertilization treatments increased tea yield, and organic fertilizer increased bud density. Organic fertilizer reduced bitter rutin and γ-aminobutyric acid content and phenol-to-ammonia ratio, and increased theanine, glutamic acid, quercetin-3-O-glucoside, kaempferol-3-O-rutinoside, and (-)-epicatechin-3-O-gallate content, resulting in umami taste and bright green color of green tea. Nine key differential volatiles were screened, and organic fertilizer markedly increased the levels of floral and fruity volatiles, including indole, decanal, linalool, geraniol, and cis-jasmone, resulting in lasting orchid aroma. Transcriptome analysis showed that organic fertilizer upregulated genes related to phenylalanine conversion and fatty acid metabolism, resulting in excellent tea quality. The results provide robust support for precise quality improvement in tea production.