Through multi-factor field experiments on the clonal tea variety Shaancha 1, researchers found that applying 180 kg N ha⁻¹ together with 40% shading for seven days improved plant growth by boosting antioxidant capacity, stabilizing photosynthesis, and optimizing the accumulation of key quality components.
Modern tea production relies heavily on nitrogen fertilizers to support vigorous growth and enrich amino acids, polyphenols, and other metabolites essential for tea quality. However, long-term over-application—often exceeding 450 kg N ha⁻¹ in Chinese tea plantations—has led to soil acidification, reduced nitrogen-use efficiency, and contributed to widespread environmental pollution. Meanwhile, intense summer light frequently induces heat and photo-oxidative stress in tea plants, compromising leaf quality and reducing yield. Shading, an established agronomic practice, can alleviate light stress, adjust microclimates, and modulate carbon–nitrogen metabolism. Due to these challenges, integrating nitrogen-reduction strategies with shading management requires systematic study to develop effective and sustainable tea-growing guidelines.
A study (DOI: 10.48130/bpr-0025-0022) published in Beverage Plant Research on 30 September 2025 by Chunmei Gong's team, Northwest A&F University, offers a practical, eco-friendly alternative to traditional high-nitrogen fertilization regimes and provides actionable strategies for reducing agricultural emissions while preserving premium tea quality.
To evaluate how nitrogen fertilization interacts with shading to influence tea plant performance, this study conducted a systematic set of field experiments combining four nitrogen levels with varying shading durations and intensities, followed by comprehensive statistical analyses of growth traits, chlorophyll characteristics, photosynthetic physiology, antioxidant responses, and key quality components. The growth assessment showed that applying N1–N3 fertilization significantly enlarged the leaf area of new shoots, particularly under N3, while short-term low-intensity shading (T1, S1) further enhanced leaf expansion and internode elongation; in contrast, high-intensity shading (S2) inhibited new shoot emergence, especially at low nitrogen levels. Morphological observations revealed that shading deepened leaf greenness, and chlorophyll measurements confirmed that all shading treatments markedly increased chlorophyll a and b without altering their ratio, indicating that greener leaf color was driven by total chlorophyll accumulation. Photosynthetic measurements using the GFS-3000 system demonstrated that N2 and N3 lowered leaf temperature and, when combined with mild shading (T1S1), maintained a photosynthetic rate comparable to full light; however, prolonged or high-intensity shading sharply reduced PAR and suppressed photosynthesis. Antioxidant analyses showed that nitrogen fertilization elevated SOD and POD activities as well as soluble protein and sugar contents, while shading increased SOD and CAT but reduced POD, MDA, and soluble sugars, reflecting an adaptive enhancement of stress mitigation under combined treatments. Quality component analyses revealed that nitrogen fertilization increased tea polyphenols, amino acids, dry matter, and water extract, whereas shading favored free amino acids and caffeine but reduced polyphenols and flavonoids under strong shade. Integrating all indicators, the combination of 180 kg N ha⁻¹ with short-term, low-intensity shading (T1S1) yielded the most balanced improvements in growth, photosynthetic performance, antioxidant capacity, and tea quality.
The findings highlight a practical cultivation strategy for producers aiming to reduce fertilizer inputs without compromising tea yield or sensory quality. Implementing short-term shading alongside moderate nitrogen application improves antioxidant capacity, stabilizes photosynthesis under summer light stress, and enhances the biochemical composition of fresh leaves. This integrated management model can reduce fertilizer costs, lower environmental emissions, and support national and international efforts promoting green, low-input agriculture. For tea enterprises, the optimized combination not only sustains production but also enhances raw-leaf quality, particularly during summer seasons when quality typically declines—offering greater market competitiveness and long-term ecological benefits.
