【目的】竹林扩张会造成茶园生态系统环境发生变化,形成明显的环境异质性,对茶树生长和茶叶品质产生不容忽视的影响。揭示竹林扩张对茶树生长及茶叶品质的潜在影响,为竹林扩张茶园的科学管理提供参考依据。【方法】以浙江龙游连续成片的茶(Camellia sinensis)-苦竹(Pleioblastus amarus)扩张林分为研究对象,设置3种样地,分别为茶竹混交林界面区、混交林中心区和茶树纯林区,测定茶树生长特性、茶叶色素、茶多酚、咖啡碱、游离氨基酸以及矿质营养元素含量等指标,通过多元统计方法、正交偏最小二乘法-判别分析和变量投影重要性法分析茶园苦竹扩张后茶树生长特性和茶叶品质的差异。【结果】①苦竹扩张对茶树的生长量和分叉数有明显影响,对平均高度存在显著影响(P<0.05)。②茶园中苦竹不断扩张,对茶叶色素含量无明显影响,但对混交林界面区茶叶叶绿素a/b有显著影响(P<0.05),但色素含量的差异对茶叶品质无显著影响。③受苦竹扩张影响,混交林界面区茶叶茶多酚和咖啡碱含量显著低于中心区和茶树纯林区(P<0.05),而酚氨比变化不明显,三者对茶叶品质均有重要贡献。④沿苦竹扩张茶园方向,茶叶中14种游离氨基酸组分含量呈增多的变化趋势,但混交林界面区和中心区甲硫氨酸和半胱氨酸含量显著高于茶树纯林区(P<0.05),丝氨酸含量在混交林中心区最高,但变化不明显,三者对茶叶品质具有重要贡献;⑤苦竹扩张茶园方向,茶叶中钙、锰、镁、铁和铜元素含量显著减少(P<0.05),在混交林界面区明显积累,而锌元素含量变化相反,这些矿质营养元素含量的变化对茶叶品质的差异性贡献大。【结论】苦竹扩张会引起茶树生长策略的改变,同时对茶叶的有效成分和矿质营养元素含量产生影响,进而对茶叶的品质产生影响,这种变化不利于提升茶叶的品质。

【Objective】The expansion of bamboo forests leads to environmental heterogeneity within the tea plantation ecosystem, exerting a significant impact on the growth of tea plants and the quality of tea leaves. Unveiling the potential effects of bamboo forest expansion on the growth of tea plants and the quality of tea leaves is paramount for the scientific management of tea plantations undergoing bamboo expansion.【Method】The study focused on the continuous patches of bitter bamboo (Pleioblastus amarus) and tea (Camellia sinensis) tree expansion forests in Longyou County, Zhejiang Province. Three types of plots were established, namely, the tea-bamboo mixed forest interface zone, the mixed forest center zone, and the pure tea plantation zone. Various parameters, including growth characteristics, tea pigments, tea polyphenols, caffeine, free amino acids, and mineral nutrients in tea leaves, were measured. The differences in the growth characteristics of tea trees and tea leaf quality after the expansion of P. amarus into tea plantation were analyzed using multivariate statistical methods, orthogonal partial least squares-discriminant analysis, and variable projection importance methods.【Result】(1) The expansion of P. amarus significantly influences the growth and branching number of tea plants, with a notable impact on the average height (P< 0.05). (2) With the expansion of P. amarus into tea plantations, there was no significant impact on the pigment content of tea leaves. However, there was a significant effect on the chlorophyll a/b of tea leaves in the mixed forest interface zone (P<0.05). The impact of pigments did not significantly contribute to tea leaf quality. (3) Influenced by the expansion of P. amarus, the contents of tea polyphenols and caffeine in the interface zone were significantly lower than those in the mixed forest center and pure tea plantation zones (P<0.05). The change in ratio of phenol to ammonia was not obvious, and all three parameters contribute significantly to tea leaf quality. (4) With the expansion of P. amarus into tea plantations, there was an increasing trend in the content of the 14 free amino acid components in tea leaves. However, in the mixed forest interface and center zones, the contents of methionine and cysteine were significantly higher than in the pure tea plantation zone (P<0.05). The content of serine was highest in the mixed forest center zone, but the change was not obvious. All three amino acids contributed significantly to tea leaf quality. (5) With the expansion of P. amarus into tea plantations, there was a significant decrease (P<0.05) in the content of calcium, manganese, magnesium, iron, and copper elements in tea leaves. These elements were noticeably accumulated in the mixed forest interface zone, while the zinc content exhibited an opposite trend. The variations in these mineral nutritional elements contribute significantly to the differences in tea leaf quality.【Conclusion】The expansion of P. amarus induced changes in the growth strategy of tea trees, altered the composition of effective components and mineral nutrient elements in tea leaves, thereby influencing tea quality and hindering its improvement.