Background : The continuous cropping of Cnidium officinale is a serious problem for the cultivation practices, which is an unelucidated subject. This study is concerned mainly with rhizosphere microbiome and meteological factors on the cause of physiological damage in the continuous cropping of Cnidium officinale.
Methods and Results : Microbial population and community dynamics was evaluated with metagenomic DNA by IonTorrent PGM. Results of HPLC profiling revealed that metabolic components of symbiotic interaction with Cnidium officinale was not detected in cultivated soils. Proteobacteria groups such as nitrogen fixing bacteria, Pseudomonas and Burkholderia of rhizosphere soil in continuous cropped fields mainly decreased compared to the first cropped soil. Principle component analysis of bacterial community showed a significantly differentiated vector between first cropping field and continuous cropped fields. Although growth characteristics including height, leaf length, leaf diameter amd stem diameter etc., was not different with continuous cultivation year until mid-July, physiological damage was dramatically started from late July. Yield of Rhizoma in continuous cropped fields significantly decreased compared to first cropped field. Evapotranspiration of Cnidium officinale with lysimeter for summer season was evaluated. It showed high relationship between solar radiation and evapotranspiration with R2 = 0.7778 and 41% of solar radiation converted into evapotranspiration during 16 days. This result imply that evapotranspiration is mainly controlled by radiation energy in clear days. Water and heat cycle through evapotranspiration is suppose to be one of the important factors related with physiological disorder of Cnidium officinale.
Conclusion : This result imply that physiological damage resulted from continuous cropping is involved in decrease of Proteobacteria at rhizosphere soils under stressed conditions.