Effects of Bio-organic Fertilizers Combination with Chemical Fertilizer Reduction on the Soil Microbial Flora and Its Correlation of Bacterial Wilt of Flue-cured Tobacco

Purpose The field experiment was carried out to study the effects of bio-organic fertilizer on soil microbial flora and the correlation between it and bacterial wilt of flue-cured tobacco with chemical fertilizer reduction.

Method The BIOLOG ECO micro plate method, dilution plate counting method, correlation analysis and other methods for test purposes were used to analyze and discuss through the field plot experiment for 5 consecutive years.

Results Compared with conventional fertilization (100% fertilizer, CF), fertilizer reduction 10% with biological organic fertilizer (BOF1) and reduction 20% with biological organic fertilizer (BOF2) production of flue-cured tobacco increased by 18.50% and 27.35%, respectively. BOF1 and BOF2 increased the proportion of superior tobacco by 13.05% and 18.14%, respectively. BOF1 and BOF2 increased the number of bacteria by 41.38% and 89.66% respectively, actinomyces increased by 185.06% and 286.21% respectively and total microbes increased 41.27% and 89.73% respectively, than that of CF. Combined with CF, the fungi amount reduced 32.07% and 51.25% respectively, bacterial wilt pathogen reduced by 53.41% and 57.04% respectively. Compared with that of CF, BOF1 and BOF2 decreased the fungi amount by 32.07% and 51.25% respectively, and bacterial wilt pathogen reduced by 53.41% and 57.04%, respectively. But, BOF1 and BOF2 increased the soil microbial evenness index and dominance index significantly than that of CF. Correlation analysis showed that the incidence of bacterial wilt of flue-cured tobacco had a significantly positive correlation with the number of pathogenic bacteria and fungi (P<0.01). But the incidence of bacterial wilt had a significantly negative correlation with total bacteria, actinomyces and microbial diversity index (P<0.01). The yield and quality of flue-cured tobacco were significantly positively correlated with the number of bacteria, actinomycetes, total microbial biomass and diversity index (P<0.01), and significantly negatively correlated with the number of bacterial wilt pathogens (P<0.01).

Conclusion Under the condition of fertilizer reduction for 5 consecutive years, the production value and quality of flue-cured tobacco can be continuously increased by applying bio-organic fertilizer on combination with fertilizer reduction, the soil microflora can be improved and the quantity of pathogenic bacteria can be reduced.