Effects of Inorganic, Organic and Bio-Organic Fertilizer on Growth, Rhizosphere Soil Microflora and Soil Function Sustainability in Chrysanthemum Monoculture

The production of chrysanthemums is severely hampered by Fusarium wilt, which is exacerbated by monoculture. In this study, the role of inorganic plant nutrition fertilizer (IPN), organic fertilizer (OF) and bio-organic fertilizer (BOF) in avoiding monoculture-related production constraints was evaluated. We conducted a series of greenhouse experiments and studied the growth of chrysanthemum and changes in rhizosphere soil microflora and function. BOF application reduced the incidence of Fusarium wilt by 82.8% and increased the chrysanthemum shoot height and flower ray floret number by 31.4% and 26.1%, respectively. High-throughput Illumina HiSeq2500 sequencing results indicated that BOF and OF treatments increased the values of α-diversity indices of bacteria and fungi. In addition, significant alterations in microbe community structures were found in response to IPN, OF or BOF application. Among the major genera detected after BOF treatments, the levels of Fusarium and Glycomyces decreased while Cladosporium, arbuscular mycorrhizal and endophyte groups increased. In particular, the abundance of Mariniflexile had a positive relationship (R = 0.693, p < 0.05) with the incidence of Fusarium wilt, while Cladosporium showed a significant negative relationship (R = −0.586, p < 0.05). Interestingly, an analysis of microbiomes based on 16S rRNA sequences revealed that the functions of signal transduction, bacterial secretion system, oxidative phosphorylation and the metabolism of carbohydrate, nitrogen and amino acids all increased in both BOF and OF treatments. The results suggested that BOF could be effective for chrysanthemum monoculture soil restoration, potentially by altering the microbial community structures and functions, which affect the physiological and morphological attributes of chrysanthemum in monoculture.