生产中氮肥施用及其对中药材产量和质量的影响

Current situation of nitrogen application and its effects on yield and quality of Chinese materia medica

氮肥是药用植物栽培中施用频率最高的化肥,对药用植物产量具有突出贡献。由于普遍认为氮肥的使用可提升中药材产量,中药材栽培中存在较严重的偏施、过量施氮的现象。该文首先总结了自1998年起我国配方施肥研究中对不同中药材的建议施氮浓度,发现不同中药材品种在不同产地对氮的需求情况呈现较大差别(0~1 035.55 kg·hm^(-2)),这既与中药材品种有关,也与不同产地的土壤肥力程度有关。其次,归纳了施氮对中药材产量的影响,并分析了适量施氮能够提高中药材产量,但过量施氮可能导致产量降低的原因,认为这主要与施氮后中药材营养物质含量、水分利用率、光合作用能力等的变化有关。最后,阐明了施氮对中药材质量的调控作用及机制,通常适量施氮会增加中药材中的含氮次生代谢物,降低非含氮次生代谢物含量,施氮对不同次生代谢物的影响主要与其合成途径有关,同时还可能受植物营养状态的影响。综上,虽然适量施氮能促进中药材产量及某些次生代谢物含量的提升,但施氮还可能降低某些非含氮次生代谢物含量,减低中药材质量,同时过量施氮也无法进一步增加中药材的产量。因此,应在前人研究基础上合理规划施氮浓度,配方施肥,该文旨在为中药材种植中氮肥的合理施用提供思路和参考。

Nitrogen fertilizer has been the long-lasting crucial component in cultivation of Chinese materia medica(CMM) and crops for its profound effects on enhancing the productivity. In consideration of its role in better production, intensive and excessive application of N fertilizer is often found in CMM cultivation. Therefore, firstly, this review summarized various concentrations of N application with regards to different CMM and districts from the literatures published in the last two decades. The recommended concentration of nitrogen application of forty seven CMM species were covered in this review. We found that the optimum rates of nitrogen fertili-zer for different medicinal plants species were varied in the range between 0-1 035.55 kg·hm^(-2). Most of the optimum rates of nitrogen fertilizer for CMM in published researches fell between 100-199 kg·hm-2. The optimum rate of nitrogen fertilizer is not only related to amount of nitrogen required for different medicinal plants but also to soil fertilities of different fields. In addition, we outlined the diffe-rent effects of proper and excessive nitrogen deposition on yield of CMM. Proper nitrogen deposition benefits the yield of CMM, howe-ver, excessive nitrogen use accounts for a decrease in CMM yield. We elucidated that nutritional content, water use efficiencies, and photosynthesis capacity were major influencing factors. Researches showed that proper nitrogen fertilizer could promote the water use efficiencies of plants and boost photosynthesis. Consequently, the yield of CMM can be enhanced after nitrogen deposition. However, negative effects of nitrogen fertilizer were also found on plant including producing toxic substances to the soil and causing severe pest damages. Lastly we analyzed the impact of N fertilizer application on secondary metabolites which accounts for a large part of active pharmaceutical ingredients of CMM. It usually caused an increase in nitrogen-containing secondary metabolites content and a decrease in non-nitrogen-containing secondary metabolites content respectively. The potential underlying mechanisms are the different synthetic pathways of these metabolites and the plant nutritional status. Synthesis of non-nitrogen-containing secondary metabolites like phenols can be inhibited after nitrogen application because of the competition of the same precursor substances between metabolites synthesis and plant growth. To sum up, impacts and mechanisms of nitrogen fertilizer on yield and quality enhancement of CMM were discussed in this review. Negative effects of excessive nitrogen application on CMM should be paid special attention in CMM cultivation and prescription fertilization based on the field soil quality is strongly recommended. Overall, this review aims to provides insights on improving the proper application of N fertilizer in the cultivation of CMM.