Effect of humic acid of media on tobacco seedling-growing in float tray system.

Media produced by 28 manufacturers in 10 tobacco producing provinces were selected for detection and seedling experiments to explore the relation between humic acid content and seedlings.The results showed that there was a certain degree of positive correlation between humic acid content and seedling growth.Humic acid content had remarkable effect on tobacco seedling growth,while the rate of emergence and quality of tobacco seedling would be reduced when humic acid content was greater than 60 %.