不同氮素形态、pH对茶树元素吸收及有机酸含量影响

以茶树龙井43为材料,利用营养液水培试验研究了不同氮素形态、pH对茶树体内阴阳离子和有机酸的影响,初步明确茶树养分吸收与氮素形态及pH的关系。结果表明,与NO_3^--N处理相比,NH_4^+-N处理提高-的含量以及根中N、SO_4^2-含量,但是NH_4^+-N处理降低了茶树对Ca、Mg、B、Mn、Zn的吸收,也减少了成熟叶中SO_4^2-、根中H_2PO_4^-的累积量。与其他处理相比,NO_3^--N处理提高了成熟叶中苹果酸、草酸、柠檬酸浓度。茶树对养分的吸收、积累也与介质pH有关,尤其是pH与氮素互作时。在NO_3^--N处理下,pH 6.0显著提高了茶树对B、Mn、Zn的吸收和根中K、Ca、Mg浓度。茶树中有机酸含量受pH影响较大,与pH 4.0和pH 5.0相比,pH 6.0提高了茶树成熟叶中苹果酸、柠檬酸、草酸浓度以及根中草酸浓度。茶树对养分的吸收、积累与自身体内有机酸浓度有较好的相关性,茶树中全氮含量与柠檬酸、草酸浓度具有显著负相关性,而阳离子Zn²⁺、Ca²⁺、Mg²⁺、Mn²⁺含量与柠檬酸、草酸浓度具有显著正相关性。

Effects of Nitrogen Form and Root-zone pH on Nutrient Uptake and Concentrations of Organic Anions in Tea Plants (Camellia sinensis)

In this study, effects of different nitrogen forms and root-zone pH on nutrient uptake and concentrations of organic anions were preliminarily confirmed in hydroponically cultured Camellia sinensis cv. Longjing 43 seedlings. The results show that tea plants supplied with NH₄⁺-N had higher concentrations of N, Fe and Cl^- in the mature leaves and N, SO₄^2- in the roots than those receiving nitrate (NO₃^--N). In contrast, tea plants receiving NH₄⁺-N had lower concentrations of Ca, Mg, B, Mn, Zn in the whole plant, SO₄^2- in the mature leaves and H₂PO₄^- in the roots than those were cultured with NO₃^--N. Tea plants treated with NO₃^--N had higher concentrations of malate, oxalate, citrate in the mature leaves than those grown with NH₄⁺-N or NH₄⁺-N+NO₃^--N. Root-zone pH significantly affected nutrient contents in tea plants, especially when it interacted with nitrogen forms. The contents of K, Ca, Mg in roots and B, Mn, Zn in whole plant at pH 6.0 were higher than those at pH 4.0. Simultaneously the concentrations of malate, oxalate,citrate in the mature leaves and oxalate in the roots were generally increased at pH 6.0. Otherwise, the content of total N had a significantly negative correlation with the concentrations of Ca, Mg, citrate, oxalate. Moreover, the concentrations of Zn²⁺, Ca²⁺, Mg²⁺, Mn²⁺ were positively correlated with citrate and oxalate.