Roots are important for the nutrition absorption of Flue-cured tobacco. In this study

by changing the amount of biochar in the soil

the effects of biochar on root system development

leaf photosynthetic characteristics

and physiological parameters of the coordinated growth of the aboveground and underground of flue-cured tabacco were investigated. A field experiment was carried out in 2015 and 2016

and there was six treatments

i.e. CK

T1

T2

T3

T4

and T5. Compared with the conventional fertilization

the nitrogen fertilizer application rate of each treatment was decreased by 40%. In the key growth period of flue-cured tobacco

root system growth characteristics and leaf photosynthetic characteristics were determined. The results showed that biochar application at 2 400 kg/hm2 increased root vigor by 177.8%

total root area by 91.35%

the total root tip number by 100.9%

leaf area by 73.29%

chlorophyll relative value by 57.68%

net photosynthetic rate by 77.32%

and leaf area coefficient by 23.48%

respectively. Biochar could effectively promote the growth and development of the root of flue-cured tobacco

optimize root physiological parameters

and improve leaf photosynthetic physiological and leaf development parameters through the improvement of root development

with the improvement effects of biochar ranching a peak in T4.