Effects of Biochar and Seaweed Fertilizers on Tobacco Growth, Soil Properties and Bacterial Wilt Occurrence

To investigate the effects of different amounts of biochar and seaweed fertilizers on tobacco growth and resistance to bacterial wilt, field experiment was conducted with complete random design using tobacco NC102 as material in the tobacco bacterial wilt disease-prone areas. On the basis of conventional fertilization, six treatments were set including CK (control), BC1 (9000 kg/ha biochar), BC2 (15 000 kg/ha biochar), BC3 (22 500 kg/ha biochar), SW (2250 kg/ha seaweed fertilizer) and BC2 + SW (15 000 kg/ha biochar+2250 kg/ha seaweed fertilizer).The results showed that single or combined application of seaweed fertilizer and biochar whether promoted the growth of tobacco. Although excessive application of biochar inhibited tobacco growth at rosette stage, it promoted growth at vigorous growing stage. Furthermore, the application of biochar and seaweed fertilizer significantly increased soil pH and soil nutrient content, reduced the incidence of tobacco bacterial wilt and its disease index, increased the yield of flue-cured tobacco and the proportion of middle and superior tobacco leaves, improved the intrinsic quality of tobacco leaves by coordinating the chemical composition. The Pearson correlation coefficient was used to reflect the relationship between the physical and chemical properties of soil and the indicators of tobacco bacterial wilt of different treatments. The results showed that appropriately improving soil pH can be an important strategy to prevent and control tobacco bacterial wilt and improve the quality of flue-cured tobacco in the main acid producing areas.