Effects of Biochar Amendment on Tomato Bacterial Wilt Resistance and Soil Microbial Amount and Activity

Abstract

Bacterial wilt is a serious soilborne disease of Solanaceae crops which is caused byRalstonia solanacearum. The important role of biochar in enhancing disease resistance in plants has been verified; however, the underlying mechanism remains not fully understood. In this study, two different biochars, made from peanut shell (BC1) and wheat straw (BC2), were added toRalstonia solanacearum-infected soil to explore the interrelation among biochar, tomato bacterial wilt, and soil microbial properties. The results showed that both BC1 and BC2 treatments significantly reduced the disease index of bacterial wilt by 28.6% and 65.7%, respectively. The populations ofR. solanacearumin soil were also significantly decreased by biochar application.Ralstonia solanacearuminfection significantly reduced the densities of soil bacteria and actinomycetes and increased the ratio of soil fungi/bacteria in the soil. By contrast, BC1 and BC2 addition to pathogen-infected soil significantly increased the densities of soil bacteria and actinomycetes but decreased the density of fungi and the ratios of soil fungi/bacteria and fungi/actinomycetes. Biochar treatments also increased soil neutral phosphatase and urease activity. Furthermore, higher metabolic capabilities of microorganisms by biochar application were found at 96 and 144 h in Biolog EcoPlates. These results suggest that both peanut and wheat biochar amendments were effective in inhibiting tomato bacterial wilt caused byR. solanacearum. The results suggest a relationship between the disease resistance of the plants and the changes in soil microbial population densities and activity.

Biochar Suppresses Bacterial Wilt of Tomato by Improving Soil Chemical Properties and Shifting Soil Microbial Community

“…Biochar can enhance the resistance of plants against different diseases [17,18,46]. In the present study, wheat biochar amendment significantly reduced the disease severity of bacterial wilt caused by R. solanacearum, thereby confirming our previous findings that biochar can be used as an amendment to control bacterial wilt [32]. The mechanisms of biochar-mediated plant resistance against plant diseases may stem from several mechanisms, such as detoxifying the chemical agents, stimulating the nutrient uptake of plants, improving soil properties, influencing soil microbial communities, and inducing plant resistance [15,24,26].…”

“…Biochar application may also change the soil community structure and subsequently result in the antagonism, competition, or parasitism of microorganisms and pathogens in the soil to reduce the amount of pathogenic bacteria [26]. Our previous study explored that wheat and groundnut biochar-mediated bacterial wilt resistance were associated with the increase in soil bacteria and actinomycete densities and the reduction in soil fungi/bacteria and fungi/actinomycetes ratios [32]. Alpha diversity analysis of microbial communities revealed no significant differences in bacteria richness and diversity among different treatments (Table 3), which is consistent with the findings of Rutigliano et al [57] and Luo et al [58].…”

“…Crop residues are one of the major source materials for producing biochar by pyrolysis. Our previous study revealed that wheat and peanut biochar has a significant role in enhancing tomato resistance against bacterial wilt, and wheat biochar showed better effects [32]. In this study, we further investigated the effects of wheat biochar application on soil chemical properties and enzymatic activity.…”

Biochar-Mediated Control of Phytophthora Blight of Pepper Is Closely Related to the Improvement of the Rhizosphere Fungal Community

“…There are many studies showing the influence of feedstock, pyrolysis temperature, and application dose of biochar on their disease control effects ( Jaiswal et al, 2014 , 2015 ; Lu et al, 2016 ; Wang et al, 2017 ; Chen et al, 2020 ), but not one focused on the biochar application time. The application of biochar just before planting may maximize the control effect because of the short-term effect of biochar on soil biological properties ( Farrell et al, 2013 ; Jiang et al, 2016 ).…”

Diversity of bacterial strains in biochar-enhanced Amazon soil and their potential for growth promotion and biological disease control in tomato

“…Through increases in bacterial abundance and changes in microbial community structure, biochar soil-enrichment can exert a significant role on disease suppression and plant growth promotion, either through direct antagonism or indirectly via induction of systemic resistance in the plant (Jaiswal et al 2018). Biochar amendments in soil can reduce the severity of bacterial wilt caused by Ralstonia solanacearum on tomato (Lu et al 2016), induce resistance to the pathogens Botrytis cinerea and Leveillula taurica in both pepper and tomato, and the pest Polyphagotarsonemus latus in pepper (Elad et al 2010), and improve considerably the growth of tomato plants, as they become more resistant to Fusarium oxysporum and Ralstonia solani (Khalifa and Thabet 2015).…”