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

Abstract

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. 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. 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. Maize straw is an effective BSD organic material, which might also provide a potential and environment-friendly 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.