普通青霉D12和罗伊氏乳杆菌发酵产物促进平邑甜茶幼苗生长和连作土壤生物环境改善

  【目的】  研究普通青霉D12和罗伊氏乳杆菌及其混合发酵产物对苹果幼苗生长及土壤环境的影响，为缓解苹果连作障碍提供绿色生防措施。  【方法】  以32年苹果园土和平邑甜茶幼苗为试材进行盆栽试验。普通青霉D12 (R1)和罗伊氏乳杆菌(R2)活化后制成活菌数分别≥2×109 CFU/mL和 ≥3×109 CFU/mL 的发酵产物。盆栽试验设置了4个处理:不加菌对照 (CK)、普通青霉D12发酵产物处理(R1)、罗伊氏乳杆菌发酵产物处理 (R2)及以上两种发酵产物1∶1混合处理(R3)。施用发酵产物后38、69和100天，测定了植株生物量、根系呼吸速率、土壤酶活性和土壤微生物等指标。  【结果】  3个发酵产物处理均促进了平邑甜茶幼苗的生长，促进效果表现为R3>R1>R2>CK。施用发酵产物后第100天，R3处理幼苗的株高、地径、鲜重、干重、根系呼吸速率与对照相比分别增加了7.7%、17.4%、50.82%、37.5%、17.04%。3个发酵产物处理不同程度地增加了土壤酶活性， R3处理第100天，土壤中脲酶、磷酸酶、蔗糖酶活性与对照相比分别增加了66.67%、34.24%、25.49%。3个发酵产物处理促进了平邑甜茶幼苗根系抗氧化酶活性，促进效果以R3处理最好，在其处理的第100天，幼苗的SOD、POD和CAT活性与对照相比分别增加了29.19%、92.62%和39.59%。PCoA分析和聚类分析结果表明，施用发酵产物后连作土壤真菌群落变化较大，且单一发酵产物处理(R1和R2)与混合发酵产物处理(R3)对连作土壤真菌群落结构的影响是不同的。施用发酵产物后，土壤中可培养细菌数量增加，可培养真菌数量降低，发酵产物混合处理(R3)土壤中的腐质霉属 (Humicola)、被孢霉属 (Mortierella)的相对丰度分别增加了73.61%、137.72%，镰孢菌属 (Fusarium)、链格孢属 (Alternaria)的相对丰度分别降低了52.48%、73.35%。相关性分析结果表明平邑甜茶生物量、根系呼吸速率和根酶活性与土壤脲酶活性存在极显著正相关，地径与真菌数量、镰孢菌属、链格孢属和枝孢菌属存在极显著负相关。  【结论】  施用普通青霉和罗伊氏乳杆菌发酵产物能够促进平邑甜茶幼苗生长，提高根系呼吸速率及SOD、POD和CAT活性，提高土壤酶活性，并改善连作土壤微生物群落结构，可作为防控苹果连作障碍的绿色有效措施。

Application of fermentation products of Penicillium commune D12 and Lactobacillus reuteri to stimulate the growth of Malus hupehensis Rehd. seedling and improve soil biological environment in a continuous cropping

  【Objectives】  In this paper, we studied the effects of two bacteria strains on the growth of apple seedlings and the soil biological environment, aiming to provide a green biological control measure to alleviate apple replant disease.   【Methods】  A pot experiment was conducted using soil collected from a 32-year apple orchard. We rejuvenated and processed Malus hupehensis Rehd., Penicillium commune D12 (R1), and Lactobacillus reuteri (R2) into fermentation products with an active bacteria population of ≥2×109 CFU/mL and ≥3×109 CFU/mL, respectively. The four treatments were no strain control (CK), applying R1, R2, and their mixture in a 1:1 (R3) ratio. Soil samples were collected on the 38, 69, and 100 days after application to determine enzyme activities. The samples collected at 100 days post-application were used to determine bacteria and fungi. Simultaneously, apple seedling growth, root respiration rate, and preserved enzyme activities were measured.   【Results】  The growth of Malus hupehensis Rehd. seedlings were promoted under the three fermentation products treatments. The seedlings biomass was in the order R3 >R1 >R2 >CK. At 100 days, the plant height, ground diameter, fresh weight, dry weight, and root respiration rate of R3 were 7.7%, 17.4%, 50.82%, 37.5%, and 17.04% higher than CK, respectively. The fermentation products increased the activities of soil enzymes to different degrees. Compared with CK, R3 increased the activities of soil urease, phosphatase, and invertase by 66.67%, 34.24%, and 25.49%, respectively. The fermentation products promoted the antioxidant enzyme activity in the roots of Malus hupehensis Rehd. seedlings. R3 increased the activities of SOD, POD, and CAT, by 29.19%, 92.62%, and 39.59% on the 100th day, respectively. PCoA analysis and cluster analysis showed that the application of fermentation products impacted the replanted soil fungal community. The effects of single fermentation product treatment (R1 and R2) and mixed fermentation products treatment (R3) on the replanted soil fungal community differed. Applying the fermentation products increased the number of cultivable bacteria and decreased the number of cultivable fungi in soil. The relative abundance of Humicola and Mortierella in R3 soil increased by 73.61% and 137.72%, while Fusarium and Alternaria decreased by 52.48% and 73.35%, respectively. The biomass, root respiration rate, and root enzyme activity of Malus hupehensis Rehd. seedlings were significantly positively correlated with soil urease activity. Further, the ground diameter had a significant negative correlation with the number of fungi, Fusarium, Alternaria, and Cladosporium.  【Conclusions】  The application of Penicillium commune D12 and Lactobacillus reuteri fermentation products could promote the growth of Malus hupehensis Rehd. seedlings, increase root respiration rate, SOD, POD and CAT activities, and soil enzyme activities. It improves the replanted soil microbial community structure and makes the soil environment conducive to plant growth. Therefore, the fermentation products could be an effective measure to prevent and control the apple replant disease.