An insight to rhizosphere bacterial community composition and structure of consecutive winter-initiated sugarcane ratoon crop in Southern China

Abstract

Background: Ratooning in sugarcane is a crucial strategy for ensuring the long-term sustainability of the sugarcane industry. Knowledge gap relating to the interaction between rhizosphere microbiome and ratooning crop, particularly the impact of different sugarcane cultivars on the rhizosphere microbiome in consecutive ratooning, requires additional research. The response of two different sugarcane cultivars, viz ZZ-1 and ZZ-13, were evaluated in consecutive ratooning towards the rhizosphere microbial community and cane morphological characters.

Results: Significant changes in the rhizosphere microbiome were observed in the second ratooning over the years. Several important genera were observed in high abundance during the second ratooning, including Burkholderia, Sphingomonas, Bradyzhizobium, and Acidothermus. Cultivar ZZ-13 caused more alterations in the rhizosphere microbiome than ZZ-1, resulting in a more favorable rhizosphere environment for sugarcane growth. The genotypes also varied in terms of nutrients and enzyme activity over the years. There were significant differences between the genotypes and year for number of stalks and yield was significant for genotypes, years and genotype × year.

Conclusion: This finding will help to understand thorough interactions between rhizosphere microorganisms and ratoon sugarcane and lay the foundation for promoting and maximizing yield as far as possible. In the future, this work can serve as guidance in sugarcane husbandry, mainly in Guangxi, China.

Keywords: Ratoon crop; Rhizosphere; Soil enzymes; Sugarcane; Yield.

Fig. 1

Rhizosphere enzyme activity of consecutive ratoon sugarcane. S-UE, soil urease; S-ACP, soil acid phosphatase; S-SC, soil sucrase; S-CAT, soil catalase. Box plots indicate value for each variety across years. The lowercase letter indicates the differences based on the LSD test (p < 0.05). Legends inside each subfigure indicate a significant level at genotypes, year, and genotype*year effect

Fig. 2

Pearson correlation analysis for different parameters among consecutive ratooning. A color gradient denoting Pearson correlation coefficient displayed pairwise comparisons of environmental factors and morphological characters

Fig. 3

Alpha diversity indices for consecutive ratooning sugarcane. Different lowercase letters indicate the difference based on the LSD test (p ≤ 0.05). The legend on the top indicated the varieties. A-D chao1, Shannon, Simpson, and Ace index mean values from replicated samples for each variety across 2 years

Fig. 4

Relative abundance of major bacterial phyla in the rhizosphere of ZZ-1 and ZZ-13 in consecutive ratooning sugarcane

Fig. 5

A taxonomic abundance of rhizosphere samples in 2019; B Taxonomic abundance of rhizosphere samples in 2020. Heat tree analysis illustrating the taxonomic differences between the 2 years. The color gradient and the size of the node, edge, and label are based on samples and their OTU count

Fig. 6

Beta diversity analysis. Principal coordinates analysis of the rhizosphere soil among 2 years using the Bray-Curtis algorithm. Different colors and ellipses indicate the year

Fig. 7

Hierarchal cluster analysis. A cluster analysis of rhizosphere samples during 2019 in the studied genotypes; B cluster analysis of rhizosphere samples during 2020

Fig. 8

A Monthly mean rainfall and temperature data during the 2 years, B Humidity and sunshine data during the 2 years