Effects of maize rotation on the physicochemical properties and microbial communities of American ginseng cultivated soil

Abstract

The production of American ginseng (Panax quinquefolius L.) is severely limited by the replant disorders in China. Crop rotation with maize might reduce the replant problems, but little information is available on the effect of maize rotation on soil cultivated with ginseng. In this study, we analyzed nutrients, phenolic acids, and microbial communities in soils from the fields with continuous maize, mono-culture ginseng, and 1-, 3-, and 5-year maize rotation after ginseng. Pot experiments were also conducted to evaluate the performance of replanting ginseng in these soils. The results showed that Mn, Cu, and 5 phenolic acids in ginseng-cultivated soil were significantly decreased by maize rotation. A 5-year maize rotation significantly increased the relative abundance of beneficial soil bacteria, such as Arthrobacter, rather than decreasing the abundances of potential pathogenic genera. Clustering analysis revealed that the physicochemical properties and microbial communities of 3- and 5-year maize rotation soil were more similar to CM than to G soil. The biomass of replanted ginseng root was improved, and root disease was reduced over 3 years of maize rotation. Overall, the results showed that at least a 3-year maize rotation is needed to overcome the replant failure of American ginseng.

Figure 1

Selected physicochemical properties in soil samples and dendrogram from hierarchical cluster analysis using between-groups linkage method and the squared Euclidean distance. AN = alkali-hydrolysable nitrogen, AP = available phosphorus, AK = available potassium, TN = total nitrogen; TP = total phosphorous, SOM = soil organic matter. Error bars denote the standard deviation of the mean (n = 3) and data designated with the same letter are not significantly different (P < 0.05), according to Fisher’s least significant difference method. G = four-year cultivation of American ginseng, M = one-year cultivation of maize, CM = cultivated maize.

Figure 2

Concentrations (Mean ± SD, n = 3) of the seven phenolic acids (a,b) and their ratios (c) in soil samples and dendrogram from hierarchical cluster analysis using the between-group linkage method and squared Euclidean distance (d). Error bars denote the standard deviation of the mean (n = 3), and data designated with the same letter are not significantly (P < 0.05) different, according to Fisher’s least significant difference method.

Figure 3

Fungal (a) and bacterial (b) major genus compositions and hierarchical cluster analysis in the soil samples.

Figure 4

Fungal (a) and bacterial (b) diversity in the soil samples. The same letter above bars represents no significant difference (P < 0.05) according to Fisher’s least significant difference method.

Figure 5

Seedling survival rate (a), root growth (b,c), and root disease severity (d) of American ginseng cultivated in different soils and non-metric multi-dimensional scaling (MDS) plot based on the data Log(X + 1) transformation and Bray-Curtis similarities (e). Error bars denote the standard deviation of the mean (n = 3), and data designated with the same letter are not significantly (P < 0.05) different, according to Fisher’s least significant difference method.