Objective  Effects of the liquid fertilizer made from Sargassum horneri for vegetable seed germination and seedling growth were evaluated.

  Methods  The liquid fertilizers prepared by either enzymatic digestion or fermentation of S. horneri, a low-quality seaweed commonly found in the coastal areas, in a gradient of concentrations were applied on bok choy (Brassica chinensis), cucumber, and tomato to determine the fertilization effects on the vegetable seed germination and subsequent seedling growth in a pot experiment. Data collected were statistically analyzed by the partial least squares discriminant analysis (PLSDA).

  Results   (1) The 200x and 600x liquid fertilizer dilutions delivered the best effects on the germination of bok choy seeds with a significantly increased germination index by 11.8% over that of blank control and by 1.9% and 1.3% over those of two positive controls. On the germination of cucumber seeds, the 200x dilution had the best effect with a significantly higher index than that of blank control by 33.0% and 21.0% and by 6.7% over those of two positive controls. For the germination of tomato seeds, the 1,000x dilution performed best with a significantly increased index over that of blank control by 13.6% and by 14.4% and 19.3% over those of the two positive controls. (2) The growth indicators of the potted seedlings were significantly correlated. The effects of the liquid fertilizer on the growth of 3 vegetable categories varied, as shown by the principal component analysis (PCA). According to the PLSDA models, the fermented liquid fertilizer at 400x dilution was superior in promoting the growth of bok choy seedlings with all indices significantly higher than those of the positive control, especially, a 144% increase on fresh root weight. And at 600x dilution, the fermented liquid fertilizer had all indices on the tomato seedlings significantly higher than those of control and the highest dry plant weight that was 31% heavier than that of the positive control. In contrast, the enzymatically digested liquid fertilizer at 800x dilution was best for the growth of cucumber seedlings with significantly higher indices on all aspects than the positive control and 28% longer roots than the positive control.

  Conclusion  TheS. horneri liquid fertilizers prepared by either fermentation or enzymatic digestion significantly promoted the seed germination and seedling growth of bok choy, cucumber, and tomato in a pot experiment. The fermented fertilizer was more effective than the enzyme-digested counterpart.