Kiwifruit soft rot is a disease caused by fungal pathogens such as Botryosphaeria dothidea, which considerably restricts the development of kiwifruit industry. To provide novel management strategies against kiwifruit soft rot disease, potential biocontrol actinomycete strains were isolated from kiwifruit rhizosphere soil. A total of 21 actinomycete strains were obtained and strain SC-3 exhibited the highest biocontrol activity against B. dothidea. Based on the morphological, biochemical and molecular characteristics strain SC-3 was identified as Streptomyces albidoflavus. The SC-3 and its aseptic filtrate (AF) exhibited excellent antifungal activities against 11 tested pathogenic fungi. AF displayed antifungal effects through suppressing mycelial growth, spore germination, and the pathogenicity of B. dothidea. Electron microscopy analysis revealed that AF could cause significant alterations on ultrastructure of B. dothidea. Moreover, AF severely damaged cell membrane integrity, resulting in the leakage of cellular components in B. dothidea. Metabolomic analyses of SC-3 AF revealed the presence of several important antifungal compounds in the AF such as antimycin, and candicidin. Correspondingly, the whole genome analyses of SC-3 identified gene clusters responsible for the biosynthesis of these compounds. Overall, SC-3 is a potential biological control agent against B. dothidea and other fungal phytopathogens.

Perennial planting of kiwifruit can easily lead to soil quality deterioration. To mitigate the negative effects of long-term kiwi cultivation on the soil, spring wheat straw is used to return to the field. The results showed that the longer the duration of straw returning to the field, the more pronounced the effect on soil quality improvement. The contents of SOM, AP, TN, and Alkaline-N were significantly higher in the Y10 plot (10-year-old kiwifruit plot) than in the Y1 plot (1-year-old kiwifruit plot) and the Y6 plot (6-year-old kiwifruit plot). The contents of these nutrients are 189.16%, 110.91%, 98.65% and 41.03% higher than Y1, respectively. Straw returning increased soil nutrients and enzyme activities (S-NP, S-SC and S-CL) and reduced soil acidification. Straw-returning treatment also enriched beneficial microbial groups (Ascomycota, Basidiomycota, Streptophyta, Mucoromycota, etc.) and changed functional groups and cellulolysis related to environmental stress. PLS-PM analysis showed that the years of straw returning to the field affected soil microorganisms' composition and functional adaptability by affecting soil nutrients and enzyme activities. These findings provide a feasible way to solve the problem of soil quality damage caused by long-term planting of kiwifruit.