For better use of wood residues from charcoal industry, poplar vinegar was studied on rape (Brassica napus L.) by pot experiment. Poplar vinegar was sprayed on leaves at seedling stage. Application concentration of wood vinegar was diluted 600, 500, 400, 300, 200, 150, 100, 50 and 10 times with water control. Two sowing dates were set up as March 14 and April 4. The wood vinegar solutions were sprayed on seedlings of 3-leaves and 8-leaves periods respectively at both sowing dates. Results showed that 10 traits were increased by spraying 300-500 times wood vinegar on both periods. The 10 traits included root dry weight, stem dry weight, leaf dry weight, total dry weight, plant height, root neck diameter, maximum leaf length, maximum leaf width, leaf area and specific leaf weight. Among them, the increase reached 3.04%-41.98% on root dry weight, 35.74%-68.27% on stem dry weight,19.80%-55.90% on leaf dry weight, 27.14%-57.02% on plant total dry weight. The leaf area increased by 50.97%-85.53% 400 times compared with control. When the wood vingar was in 10-50times, rapeseed growth was signifi⁃
cantly inhibited. Between the 2 periods, spraying at 3-leaves significantly increased the growth of root, stem and leaves. Conisidering of root shoot ratio, the wood vinegar promoted aboveground growth rather than roots. In conclu⁃sion, the application of 300-500 times diluted wood vinegar at the 3-leaves and 8- leaves periods could significant⁃ly improve plant growth on palnt height, root neck diameter, leaf area, specific leaf weight and biomass of rape. And the application effect was better with 400 times at 3-leaves period.
