Effects of adding wood vinegar to nutrient solution on the growth, photosynthesis, and absorption of mineral elements of hydroponic lettuce

This study was conducted to determine whether using wood vinegar instead of nitric acid to adjust the pH of nutrient solution in hydroponics had any effects on the lettuce. Photosynthesis, mineral elements, water absorption, and the growth of the lettuce were all comparable to those of lettuce in the control group, in which nitric acid was used to adjust the pH. Nitric acid was added to half a unit of Enshi formula to adjust the pH of the control group. The rates of growth, water and mineral element absorption, and photosynthesis were low in lettuce plants grown in nutrient solution with 1ml L-1 wood vinegar. However, the lettuce grown in solutions with 0.25ml L-1 wood vinegar showed no significant differences from the control group. Therefore, wood vinegar concentration of 0.25ml L-1 was found to be sufficient to keep the pH of the nutrient solution within the optimum range for growth.