Abstract:

Reductive soil disinfestation (RSD) is an efficient, safe, and environment-friendly method for soil sterilization. Soil protozoa play a crucial role in promoting soil nutrient cycling and plant growth. Although many studies have focused on the effects of a strong reduction in soil sterilization on bacterial and fungal communities, little attention has been paid to protozoan communities. In this study, tomato soils with long-term continuous cropping were subjected to four different RSD treatments: control, treatment with added corn stalk, treatment with added bagasse, and treatment with both corn stalk and bagasse. The RSD process involved adding organic materials according to the specified treatments, isolating the air through flooding and film mulching, and maintaining the temperature at 35 ℃ for 21 d. Soil samples were collected on the 1st, 3rd, 7th, and 21st days of natural air drying, and the 21st-day samples were selected for high-throughput 18S rRNA amplicon sequencing. The results revealed that different RSD treatments led to fluctuations in the soil total carbon and available phosphorus content during natural air drying. After RSD treatment, Cercozoa, Cilipohora, and Amoebozoa were the dominant protozoan groups, with relative abundances ranging from 19.2% to 25.9%, 13.8% to 26.9%, and 12.0% to 28.8%, respectively. RSD treatment increased the relative abundance of predatory and parasitic protozoan communities while decreasing the relative abundance of autotrophic protozoa. However, it did not significantly improve the overall diversity of the soil protozoan communities. Soil available phosphorus and ammonium nitrogen contents have emerged as key environmental factors influencing soil protozoan communities. Notably, the available soil phosphorus content was significantly correlated with the relative abundance of predator, autotrophic, and parasitic protozoan functional communities. This study underscores the significant impact of RSD treatment on the composition and function of protozoan communities in the soil.

Key words: reductive soil disinfestation, soil protist community, diversity, community function composition, high-throughput sequencing

摘要：

强还原土壤灭菌（Reductive soil disinfestation，RSD）是一种高效、安全以及环保的土壤灭菌方法。土壤原生生物是土壤微生物的重要组成部分，对土壤养分循环和植物生长起到一定的促进作用。目前关于强还原土壤灭菌对微生物群落影响的研究报道较多，但大都集中于细菌和真菌群落，较少关注原生生物群落。以长期连作番茄土壤为研究对象，设置4种不同RSD处理（对照组、添加玉米秸秆、添加甘蔗渣和添加玉米秸秆+甘蔗渣），RSD步骤为：按照上述4种不同处理添加有机物料，采用淹水和覆膜的方式隔绝空气，并在35 ℃条件下处理21 d，处理结束后在自然风干的第1、3、7和21天取样，选取第21天的土样进行高通量测序。通过高通量18S rRNA基因扩增子测序技术分析RSD处理后土壤原生生物群落组成和功能群落的变化，利用冗余分析明确影响原生生物群落的关键环境因子。结果表明，在自然风干期间不同RSD处理增加了土壤全碳含量，土壤速效磷含量呈先下降后上升再下降的变化趋势。RSD处理后丝足虫门（Cercozoa）、纤毛门（Cilipohora）以及变形虫门（Amoebozoa）为优势类群，其相对丰度分别为19.2%－25.9%、13.8%－26.9%和12.0%－28.8%。RSD处理提高了捕食型和寄生型原生生物群落的相对丰度，降低了自养型原生生物的相对丰度，并没有改善土壤原生生物群落多样性。土壤速效磷含量和土壤铵态氮含量是影响土壤原生生物群落的关键环境因子，其中土壤速效磷含量与捕食型、自养型和寄生型原生生物功能群落的相对丰度呈现显著相关性。该研究证明了RSD处理对土壤原生生物群落组成和群落功能组成有显著的影响。

关键词: 强还原土壤灭菌, 土壤原生生物群落, 多样性, 群落功能组成, 高通量测序