Effects of Trichoderma harzianum on Growth and Rhizosphere Microbial Community of Continuous Cropping Lagenaria siceraria

This study analyzed the effects of <i>Trichoderma harzianum</i> on the growth of continuous cropping <i>Lagenaria siceraria</i> and the physical and chemical properties of rhizosphere soil and microbial community structure, using Illumina Miseq (PE300) high-throughput sequencing technology along with physiological and biochemical detection. The results indicated that after applying <i>T. harzianum</i>, the growth of <i>L. siceraria</i> was significantly promoted, with increases in plant height, fresh weight, and dry weight of 21.42%, 24.5%, and 4.5%, respectively. The pH of the rhizosphere soil decreased from 7.78 to 7.51, while the electrical conductivity, the available phosphorus, the available potassium, and the total nitrogen were markedly higher compared to the control group and increased by 13.95%, 22.54%, 21.37%, and 16.41%, respectively. The activities of catalase and sucrase in the rhizosphere increased by 18.33% and 61.47%, and the content of soil organic carbon (SOC) increased by 27.39%, which indicated that <i>T. harzianum</i> could enhance soil enzyme activity and promotes the transformation of organic matter. The relative abundance of beneficial bacteria such as <i>Pseudomonas</i> increased, while the relative abundance of harmful fungi such as <i>Fusarium</i> and <i>Podosphaera</i> decreased significantly.