Fusarium wilt (FW) caused by Fusarium oxysporum f. sp. niveum (FON) is a soil-borne disease that seriously limits watermelon production. In the present study, Trichoderma asperellum (T. asperellum) M45a was shown to be an effective biocontrol agent against FW. In a pot experiment, the application of 10⁵ cfu/g of T. asperellum M45a granules had an improved control effect on FW during the blooming period (up to 67.44%) in soils subjected to five years of continuous cropping with watermelon, while the average length of watermelon vines was also significantly improved (P < 0.05). Additionally, the acid phosphatase (ACP), cellulase (CL), catalase (CAT), and sucrase (SC) activities in the M45a-inoculation group were significantly higher than those in the control (CK) group, and transformation of the soil nutrients (total N, NO3-N, and available P) was significantly increased. Moreover, T. asperellum M45a inoculation reduced fungal diversity, increased bacterial diversity and especially enhanced the relative abundance of plant growth-promoting rhizobacteria (PGPR), such as Trichoderma, Sphingomonas, Pseudomonas, Actinomadura, and Rhodanobacter. Through functional prediction, the relative abundance of ectomycorrhiza, endophytes, animal pathotrophs, and saprotrophs in the fungal community was determined to be significantly lower than that observed in the M45a-treated soil. Correlation analysis revealed that Sphingomonas, Pseudomonas, and Trichoderma had the most differences in terms of microorganism abundance, and these differences were positively correlated with ACP, CL, CAT, and SC. These findings provide guidance for the use of fungicides to achieve microecological control of FW in continuously cropped watermelon plots.

尖孢镰刀菌引起的枯萎病f。sp。Niveum（FON）是一种土壤传播疾病，严重限制了西瓜的产量。在本研究中，曲霉木霉（T. asperellum）M45a被证明是一种有效的抗FW生物防治剂。在盆栽实验中，应用10 ⁵  cfu / g的曲霉在西瓜连续种植五年的土壤中，M45a颗粒在开花期对FW的控制效果有所改善（最高67.44％），而西瓜藤的平均长度也得到了显着改善（P <0.05）。此外，M45a接种组的酸性磷酸酶（ACP），纤维素酶（CL），过氧化氢酶（CAT）和蔗糖酶（SC）活性显着高于对照组（CK）和土壤养分转化（总氮，NO3-N和有效磷）显着增加。此外，曲霉菌M45a的接种会减少真菌多样性，增加细菌多样性，尤其是增强植物促生根瘤菌（PGPR）的相对丰度，例如木霉菌，鞘氨醇单胞菌，假单胞菌属，放线，并Rhodanobacter。通过功能预测，可以确定真菌群落中表皮菌根，内生菌，动物病菌和腐生菌的相对丰度明显低于在M45a处理的土壤中观察到的相对丰度。相关分析表明，鞘氨醇单胞菌，假单胞菌和木霉菌在微生物丰度方面差异最大，且这些差异与ACP，CL，CAT和SC正相关。这些发现为在连续种植的西瓜田中使用杀真菌剂实现FW的微生态控制提供了指导。