title: Optimal fertilizer application for Panax notoginseng and effect of soil water on root rot disease and saponin contents.
abstract: BACKGROUND
  Blind and excessive application of fertilizers was found during the cultivation of Panax notoginseng in fields, as well as increase in root rot disease incidence.
  
  
  METHODS
  Both "3414" application and orthogonal test designs were performed at Shilin county, Yunnan province, China, for NPK (nitrogen, phosphorus, and potassium) and mineral fertilizers, respectively. The data were used to construct the one-, two-, and three-factor quadratic regression models. The effect of fertilizer deficiency on root yield loss was also analyzed to confirm the result predicted by these models. A pot culture experiment was performed to observe the incidence rate of root rot disease and to obtain the best range in which the highest yield of root and saponins could be realized.
  
  
  RESULTS
  The best application strategy for NPK fertilizer was 0 kg/667 m(2), 17.01 kg/667 m(2), and 56.87 kg/667 m(2), respectively, which can produce the highest root yield of 1,861.90 g (dried root of 100 plants). For mineral fertilizers, calcium and magnesium fertilizers had a significant and positive effect on root yield and the content of four active saponins, respectively. The severity of root rot disease increased with the increase in soil moisture. The best range of soil moisture varied from 0.56 FC (field capacity of water) to 0.59 FC, when the highest yield of root and saponins could be realized as well as the lower incidence rate of root disease.
  
  
  CONCLUSIONS
  These results indicate that the amount of nitrogen fertilizer used in these fields is excessive and that of potassium fertilizer is deficient. Higher soil moisture is an important factor that increases the severity of the root rot disease.
authors: Shaanxi Research Center of TCM Fingerprint and NP Library, College of Life Sciences, Northwest A&F University, Yangling, China.
authors: Pengguo
authors: P
authors: Xia
authors: Shaanxi Research Center of TCM Fingerprint and NP Library, College of Life Sciences, Northwest A&F University, Yangling, China; Department of Biology, University of British Columbia Okanagan, Kelowna, Canada.
authors: Hongbo
authors: H
authors: Guo
authors: Tianjin Tasly Modern TCM Resources Co. Ltd., Tianjin, China.
authors: Hongguang
authors: H
authors: Zhao
authors: Shaanxi Research Center of TCM Fingerprint and NP Library, College of Life Sciences, Northwest A&F University, Yangling, China.
authors: Jie
authors: J
authors: Jiao
authors: Department of Biology, University of British Columbia Okanagan, Kelowna, Canada.
authors: Michael K
authors: MK
authors: Deyholos
authors: Tianjin Tasly Modern TCM Resources Co. Ltd., Tianjin, China.
authors: Xijun
authors: X
authors: Yan
authors: Tianjin Tasly Modern TCM Resources Co. Ltd., Tianjin, China.
authors: Yan
authors: Y
authors: Liu
authors: Shaanxi Research Center of TCM Fingerprint and NP Library, College of Life Sciences, Northwest A&F University, Yangling, China; College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, China.
authors: Zongsuo
authors: Z
authors: Liang
keywords: Panax notoginseng; fertilizer; fitting model; root rot disease; soil moisture