不同氮素供应水平对菘蓝生长及药材质量的影响

为探究低氮营养对菘蓝生长及药材质量的影响,采用盆栽试验,研究不同氮素水平0(N0)、2.5(N1)、5.0(N2)、10.0(N3)、15.0 mmol·L^-1(CK)下菘蓝生物量积累、光合参数、根与叶中可溶性糖、游离氨基酸、硝态氮含量以及主要活性成分含量的响应。结果表明,不同供氮水平下菘蓝生长与药材质量的响应存在差异。随着氮素浓度的增加,叶与根的干重均逐渐增加,根冠比则先增加后减小,且在N1处理下达到最大值。叶中可溶性糖含量随着氮素浓度的增加呈先减少后增加的趋势,N0处理下达到最大值,根中可溶性糖含量的变化趋势与叶中存在差异,在2.5~15.0 mmol·L^-1氮水平下,根中可溶性糖含量呈先增加后减少的趋势,在N2处理下达到最大值。随着氮素浓度的增加,根与叶中游离氨基酸的含量均呈先增加后减少的趋势,且在N3处理下达到最大值,根和叶中硝态氮含量则呈先减少后增加的趋势,N3处理下硝态氮含量显著低于其他处理。净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)随着氮素浓度的增加均表现出先增加后减少的趋势,在N3处理下达到最大值,胞间二氧化碳浓度(Ci)呈逐渐降低的趋势。随着氮素浓度的增加,叶中靛蓝含量随之逐渐增加,靛玉红含量则表现出先减少后增加的趋势,N3处理下为最小值,总黄酮含量则呈逐渐减少的趋势。根中(R,S)-告依春含量随着氮浓度的增加呈先增加后减少的趋势,在N3处理下最高,表明适当的氮素供应有利于靛蓝与(R,S)-告依春的积累,而低氮条件有利于提高靛玉红与总黄酮含量。根中(R,S)-告依春单株产量在N3处理下最高,表明可以适当降低施氮量以获得活性成分含量较高的板蓝根。本研究结果为菘蓝规范化栽培中合理施氮提供了理论参考。

Effect of Different Nitrogen Supply Levels on the Growth of Isatis indigotica Fort. and Quality of Medicinal Materials

A pot experiment was carried out to explore the effect of different nitrogen levels on the growth of I. indigotica and quality of medicinal materials. The response of the biomass accumulation, the photosynthetic parameters, the contents of soluble sugar, free amino acid, nitrate nitrogen and main active components of I. indigotica under 0(N0), 2.5 (N1), 5.0 (N2), 10.0 (N3), 15.0 mmol·L^-1(CK) nitrogen levels were investigated. The results showed that dry weights of leaves and roots increased with the increase of nitrogen concentration, and the root-shoot ratios increased initially and then decreased. The content of soluble sugar in leaves showed a trend of decreasing initially and then increasing with the increase of nitrogen concentration. The soluble sugar content in roots showed the different trend as that in leaves. In the nitrogen concentration range of 2.5~15.0 mmol·L^-1, the soluble sugar content in roots increased initially and then decreased. The contents of free amino acid in roots and leaves increased initially and then decreased with increasing of nitrogen concentration. The free amino acid content under N3 treatment was the highest. The nitrate nitrogen contents in roots and leaves showed a trend of decreasing initially and then increasing. The nitrate nitrogen content under N3 treatment was significantly lower than that of the other treatments. The net photosynthetic rate(Pn), transpiration rate(Tr) and stomatal conductance(Gs) of leaves increased initially then decreased with the increase of nitrogen concentration, and the intercellular CO₂ concentration(Ci) decreased. The content of indigo in leaves gradually increased with the increase of nitrogen concentration, and the content of indirubin showed a trend of decreasing initially and then increasing. The content of total flavonoid in leaves showed a tendency of declining with the increase of nitrogen concentration. The content of (R,S)-epigoitrin in roots increased initially and then decreased with the increase of nitrogen concentration, and the content was highest under N3 treatment. The results indicated appropriate nitrogen supply is conducive to the accumulation of indigo and (R,S)-epigoitrin, while low nitrogen condition is favorable for increasing the contents of indirubin and total flavonoid. The (R,S)-epigoitrin yield in per plant was the highest under N3 treatment, indicating that suitably reduced nitrogen application could obtain Radix Isatidis with higher contents of active components. The study provides a theoretical reference for the reasonable application of nitrogen in the standardized cultivation of I. indigotica Fort.