Abstract:

With the continuous cropping of vegetables in protected areas, the root-knot nematodes in the soil have proliferated extensively, causing root-knot nematode disease widely, which has seriously endangered the vegetables production in protected areas. Biological control is the best measure to control root knot nematode disease because it does not endanger soil health. At present, there are few reports about the effects of earthworm in situ composting and biochar on cucumber root-knot nematodes and rhizosphere microorganisms. To explore the mechanism of the combined effect of earthworm in-situ composting and biochar on root-knot nematodes and soil microorganisms, this study targeted continuous cropping soil of cucumber as the research object, and the greenhouse soil planted with cucumber for three consecutive years as the tested soil. The cucumber variety was ‘Del 99’, and four treatments were designed as control (CK); V (earthworm in-situ treatment); B (biochar 3 t·hm^-2); VB (earthworm in-situ+biochar 3 t·hm^-2). The results showed that earthworm in situ+biochar treatment had significant effects on biological control of the number of cucumber root knots throughout the period. Among them, the population decline rates at the full fruit stage and the seedling stage were 66.51% and 80.42%, respectively. The plant incidence rate was only 13.33%, and the control efficiency was 78.57%. In addition, the control efficiency of earthworm compost and biochar on root-knot nematodes were 71.42% and -35.71%, respectively. The application of biochar alone could not control cucumber root-knot nematodes, but earthworm compost+biochar treatment had a significant effect on root-knot nematodes. High-throughput sequencing results showed that the Ace, Simpson and Shannon indices of earthworm in situ+biochar for cucumber rhizosphere bacteria were significantly higher (44.84%, 45.63% and 15.01%, respectively) than those of CK treatment (P<0.05). As for cucumber rhizosphere fungi, each treatment increased the richness and diversity of soil fungal communities compared with the control. Correlation analysis showed that Actinobacteriota and Patescibacteria bacteria were significantly and negatively correlated with the number of cucumber root nodules (P<0.05). Kernia and unclassified-f-Microascaceae fungi were significantly and negatively correlated with the number of cucumber root knots (P<0.05).

Key words: earthworm, cucumber, biochar, root knot nematode, biological control, microbial colonies

摘要：

随着保护地蔬菜连年连茬种植，土壤中的根结线虫大量繁殖，根结线虫病的发生普遍，已经严重危害保护地蔬菜的安全生产。生物防治因其不危害土壤安全被认为是防治根结线虫病的最优措施。目前关于蚯蚓原位堆肥和生物炭联合作用下对黄瓜根结线虫及根际微生物的影响鲜有报道。为探明蚯蚓原位堆肥和生物炭联合作用下对根结线虫和土壤微生物的影响机制，本试验以黄瓜连作土壤为研究对象，以连续3年种植黄瓜的设施土壤为供试土壤，供试黄瓜品种为“德尔99”，试验设计4个处理，分别为对照（CK）；V（蚯蚓原位处理）；B（生物炭3 t·hm^-2）；VB（蚯蚓原位+生物炭3 t·hm^-2）。结果表明：蚯蚓原位+生物炭处理在整个时期对黄瓜根结数量有显著的防治作用，其中在盛果期和拉秧期虫口减退率分别达66.51%、80.42%，植株发病率仅13.33%，防治效果达78.57%。另外，蚯蚓原位堆肥处理、生物炭处理对根结线虫的防治效果分别为71.42%、-35.71%，可见单独施用生物炭并不能防治黄瓜根结线虫，但是蚯蚓原位+生物炭处理对根结线虫防治效果显著。采用高通量测序技术结果表明，对于黄瓜连作土壤根际细菌而言，蚯蚓原位+生物炭与对照相比，VB处理的Ace指数、Simpson指数、Shannon指数均显著高于CK处理，分别高44.84%、45.63%和15.01%（P<0.05）。对于黄瓜连作土壤根际真菌而言，与对照相比，各处理也增加了土壤真菌群落的丰富性和多样性。相关性分析结果表明，细菌中放线菌门（Actinobacteriota）、髌骨菌门（Patescibacteria）与黄瓜根结数量呈显著负相关（P<0.05）；真菌中丝壳属（Kernia）、未分类的小囊菌属（unclassified-f-Microascaceae）黄瓜根结数量呈显著负相关（P<0.05）。

关键词: 蚯蚓, 黄瓜, 生物炭, 根结线虫, 生物防治, 微生物菌落