Influences of Biochar Application Rate on Tobacco Seedling Growth

A pot experiment was carried out to study the influences of biochar on the growth of tobacco seedling and root system.Biochars of different rates were added into soil,and the dry matter accumulation and nitrogen,phosphorus,potassium contents in tobacco seedling and the morphology and vitality of seedling root system at different biochar rates were determined.The results showed that comparing with the control,the dry matter accumulation of tobacco seedlings increased by 28.5% at a biochar application rate of 1%,however it decreased by about 7.1% and tobacco seedling growth was inhibited when the application rate was above 4%.With the increase of biochar application rate,the volume,area of the root system and total length of roots raised.At the application rate of 3%,the total length of roots reached its maximum and increased by 10.5%.At the application rate of 4%,the volume of roots reached its maximum and increased by 238.7%.Under the conditions of this experiment,the biochar application rate of 3% promoted the growth of tobacco seedlings,while over that application rate,the growth of tobacco seedlings would be inhibited.