Influence of seed coat treatments on germination and early seedling growth of Lupinus varius L.

The seed coat treatments (mechanical scarification, boiling seeds for 4, 6, 8 and 10 minutes and scarifying in concentrated sulfuric acid for 4, 8, 12, 16, 20 and 24 h) were tested to overcome the seed coat impermeability and improve germination and early seedling growth characteristics of Lupinus varius. Mechanical scarification provided rapid and highest imbibitions, germination percentage and seedling establishment, and also the highest values of early seedling growth characteristics. Embryos of L varius could survive after boiling the seeds for 4, 6, 8 and 10 minutes and final germination percentages were 68.3%, 80.0%, 71.7% and 63.3%, respectively. Boiling treatments also improved some other germination and early seedling growth characteristics compared with untreated seeds, but it was not completely able to overcome the seed coat impermeability in any durations of boiling time. Concentrated sulfuric acid treatments increased imbibitions and germination percentages and improved early seedling growth characteristics as the duration of scarification time increased. However, shoot height and root length and their dry weights decreased, and also abnormal geotropic growth occurred in radicles when seeds were scarified in sulfuric acid for 20 and 24 h. Considering similarities in most. of germination and seedling growth characteristics, scarifying seeds in sulfuric acid for 12 or 16 hours was found as alternative seed coat treatments to mechanical scarification. Results indicate that the seed coat dormancy in L. varius is harder to overcome than those of other Lupinus species and seed coats are not only impermeable but also might be heat resistant.