Diversified Soil Types Differentially Regulated the Peanut (Arachis hydropoaea L.) Growth and Rhizosphere Bacterial Community Structure

Abstract

Peanut (Arachis hydropoaea L.) demonstrates a prominent adaptability to diverse soil types. However, the specific effects of soil types on peanut growth and bacterial communities remain elusive. This study conducted a thorough examination of the agronomic traits, the corresponding physicochemical properties, and bacterial structure of rhizosphere soil in acidic (AT), neutral (NT), and saline-alkali (ST) soils, elucidating the internal relationship between soil type and peanut yield. Our results showed that different soil types exhibited significant differences in peanut yield, with ST demonstrating the lowest yield per plant, showing an 85.05% reduction compared to NT. Furthermore, available phosphorus content, urease, and invertase activities were substantially reduced in both ST and AT, particularly in ST by 95.35%, 38.57%, and 62.54%, respectively. Meanwhile, metagenomic sequencing unveiled a notable decline in Bradyrhizobium and Streptomyces in these soils, which is crucial for soil improvement. Further metabolic pathway analysis revealed that the reduction in pathways related to soil remediation, fertility improvement, and stress response in AT and ST may lead to slower peanut growth. In conclusion, peanuts cultivated in acidic and saline-alkali soils can increase yield via implementing soil management practices such as improving soil quality and refining micro-environments. Our study provides practical applications for enhancing peanut yield in low- to medium-yield fields.

Keywords: acidic soil; metagenome; peanut (Arachis hydropoaea L.); rhizosphere bacterial community; saline–alkali soil; soil type.

Figure 1

Effects of different soil types on peanut agronomic traits (a–f): main stem height (a), lateral branch length (b), number of branches (c), number of leaves (d), root dry weight (e), and shoot dry weight (f) of peanuts cultivated in different soil types. Different lowercase letters indicate significant difference at p < 0.05 among the treatments.

Figure 2

The yield components of peanuts cultivated in different soil types (a–f): yield per plant (a), number of pods per plant (b), dry weight of pods per plant (c), 100 pods weight (d), 100 seeds weight (e), and kernel rate (f) of peanuts cultivated in different soil types. Different lowercase letters indicate significant difference at p < 0.05 among the treatments.

Figure 3

Peanut rhizosphere soil physicochemical properties in different soil types (a–d): the pH (a), content of alkali-hydrolyzable nitrogen (b), available phosphorus (c), and available potassium (d) in peanut rhizosphere soil of different soil types. Different lowercase letters indicate significant difference at p < 0.05 among the treatments.

Figure 4

Soil enzyme activities in peanut rhizosphere soil under different soil types (a–d): catalase activity (a), phosphatase activity (b), urease activity (c), and invertase activity (d) in peanut rhizosphere soil of different soil types. Different lowercase letters indicate significant difference at p < 0.05 among the treatments.

Figure 5

Beta diversity and Venn diagram analysis of peanut rhizosphere bacterial community structure in different soil types. (a) PCoA analysis of peanut rhizosphere bacterial community structure in different soil types. (b) ANOSIM analysis of peanut rhizosphere bacterial community structure in different soil types. (c) Venn diagram analysis of peanut rhizosphere bacterial community structure at the phylum level in peanut rhizosphere soil in different soil types. (d) Venn diagram analysis of peanut rhizosphere bacterial community structure at the genus level in peanut rhizosphere soil in different soil types.

Figure 6

Bacterial community structure of three rhizosphere soil types at the phylum and genus levels. (a) Percent of taxa at the phylum level in diverse rhizosphere soils. The relative abundance of each taxon was calculated by averaging the abundances of three duplicates in each soil group. (b) Kruskal–Walls H test bar plot of richness at the phylum level. (c) Percent of taxa at the genus level in diverse rhizosphere soils. (d) Kruskal–Walls H test bar plot of richness at the genus level.

Figure 7

Correlation between peanut rhizosphere bacterial communities and environmental factors in different soil types. (a) Correlation between peanut rhizosphere bacterial communities at the phylum level and environmental factors in different soil types. (b) Correlation between peanut rhizosphere bacterial communities at the genus level and environmental factors in different soil types. The red arrow represents environmental factors, while the green arrow points to different bacterial phyla in (a) or genera in (b).

Figure 8

KEGG pathway enrichment of differential metabolites in peanut rhizosphere soil of different soil types. (a) Heatmap of KEGG metabolic pathways in peanut rhizosphere soil of different soil types. (b–i) Bar chart of enrichment analysis for biosynthesis of cofactors (b); degradation of aromatic compounds (c); fatty acid metabolism (d); carbon metabolism (e); biosynthesis of amino acids (f); purine metabolism (g); glycine, serine, and threonine metabolism (h); and glycolysis/gluconeogenesis (i). The * symbol and different lowercase letters indicate significant difference at p < 0.05 compared to NT.