Effect of fertilizer and harvesting stage on growth and bioactive compounds content of Rheum tanguticum

Rhubarb is a popular food in Europe due to the purgative action. Cultivation is the key way to ensure sustainable development and utilization of this herbal plant. In this paper, standardized cultivation of Rheum tanguticum (a kind of rhubarb) was explored through a three-year field experiment which investigated the effect of phosphorus (P) and potassium (K) fertilizer on growth indexes, sennoside content of R. tanguticum at different harvesting stages. Results showed that P and K fertilizer significantly increased root length, root diameter and root fresh weight, the maximum root fresh weight was 894.22 g/plant. Sennoside content of three-year-old R. tanguticum applied K fertilizer was over 5.87% at each harvesting stage in the third growth cycle and it increased along with growing year. Sennoside content has no obviously increment at the same harvesting stage, it also has no positive correlation with different harvesting stages and the wilting stage > green stage > growth stage in the same year. This study demonstrated that P and K fertilizer had accelerated effect on growth of R. tanguticum at the same harvesting stage, but had no obvious influence on the sennoside content. This will provide experimental data and guidance for the standardized cultivation of R. tanguticum.