Effects of biological soil disinfestation and water regime on suppressing Artemisia selengensis root rot pathogens

Abstract

Purpose Biological soil disinfestation (BSD) is an effective non-chemical method to control soil-borne disease by incorporating organic amendments into soil under flooding conditions. For suppressing Artemisia selengensis root rot pathogens (Fusarium oxysporum f. sp. cubense (FOC), Phytophthora spp., and Pythium spp.), the effects of BSD treatment using maize straw as organic material and water regime were investigated by greenhouse experiments. Materials and methods Pathogens infested soil was filled in greenhouse pots and incorporated with maize straw at rates of 0.2 %, 0.5 %, and 2 % (w/w) under flooded or water-saturated (100 % water-holding capacity) conditions at 25-35°C for 25 days. Results and discussion The population of A. selengensis root rot pathogens was effectively reduced after BSD treatments with all three maize straw application rates, and the largest reduction was reached up about 90 % at 2 % application rate.No obvious difference in suppressing effect was observed between flooded and water-saturated soil conditions with the same application rate of maize straw. BSD induced bacterial community structure shift and biodiversity enhancement. Two toxic organic acids producers, Clostridium and Bacillus spp., were found as predominant populations in both flooding alone and BSD treatments, while four types of organic acids, acetate, propionate, butyrate, and isovelerate were only detected in BSD treatments. Besides, increasing soil pH and organic matter with concomitantly decreasing nitrate occurred in BSD-treated soils. Conclusions Maize straw is an effective BSD organic material, which might also provide a potential and environmentfriendly disposal strategy of crop residues. Saturating soil to reach 100 % WHC was a good alternative to soil flooding in BSD. Bacterial community shifts, organic acids accumulation, and soil properties changes indicated multiple ways that might be involved in suppressing A. selengensis root rot pathogens during BSD treatment.

Effect of Different Substrates on Soil Microbial Community Structure and the Mechanisms of Reductive Soil Disinfestation

“…However, after RSD treatments, the relative abundances of organic acid producers increased, particularly in the AL groups, potentially because many Firmicutes are anaerobic bacteria and the low C/N ratio is more conducive to the formation of an anaerobic environment (Liu et al, 2016). In addition, the higher addition of substrate was related to higher relative abundance of organic acid producers, similar to the results of a study by Wen (2015). Once pathogens are inhibited, toxic organic acids are degraded during the drying process of the soil due to destruction of the anaerobic environment, thereby preventing toxicity during crop cultivation.…”

“…There were two possible reasons for this result. First, Flavisolibacter is an aerobic bacterium (Kim et al, 2018); greater substrate addition would result in more favorable formation of an anaerobic environment (Wen et al, 2015), and therefore, a high addition amount was not conducive to the growth of Flavisolibacter. Second, during the early stage of cultivation, residual oxygen in the soil and dissolved oxygen in the water could provide conditions for the survival of Flavisolibacter; Flavisolibacter increased rapidly in the presence of a sufficient carbon source.…”

“…The application of different organic materials in RSD treatment may result in different effects. Wen et al (2015) found that application of maize straw in RSD treatment can effectively inhibit Artemisia selengensis root rot pathogens and the inhibition efficiency can reach 90% when the application rate is 2%. The combined application of molasses and composted poultry litter has been shown to have strong effects on inhibiting fungi and nematodes (Rosskopf et al, 2014).…”

“…Examining the effects of substrate input amount on pathogens may facilitate optimization of the application rate of organic matter (Wen et al, 2015). Although previous studies have shown that greater input of organic material increases pathogen inhibition (Blok et al, 2000), the amount of organic material added needs to be controlled based on the growth of crops in the soil.…”

Insights into the Regulation of Rhizosphere Bacterial Communities by Application of Bio-organic Fertilizer in Pseudostellaria heterophylla Monoculture Regime

“…Moreover, we found that consecutive monoculture of P. heterophylla led to a significant increase in the relative abundance of F. oxysporum but a decrease in the potential beneficial bacteria including Burkholderia and Clostridium (Mowlick et al, 2012; Ho et al, 2015; Wen et al, 2016). Our previous studies by culture-dependent and culture-independent analysis demonstrated that F. oxysporum and other Fusarium spp.…”