Breaking Dormancy and Increasing Restoration Success of Native Penstemon Species Using Gibberellic Acid Seed Coatings and U-Shaped Furrows

Many plant species exhibit strong seed dormancy. This attribute benefits the species' long-term survival but can impede restoration when rapid establishment is required. Soaking seeds in gibberellic acid (GA(3)) can overcome dormancy and increase germination but this treatment may not be effective outside the laboratory. An easier and potentially more effective method to apply this hormone is to coat seeds with a GA(3)-impregnated polymer. Seed dormancy can also be mitigated by creating a favorable microsite with increased soil moisture. We compared the emergence and establishment of penstemon seeds coated with GA(3) to those of uncoated seeds planted in shallow drill rows versus deep, U-shaped furrows. Overall, 6 times more Palmer's penstemon (Penstemon palmeri; p < 0.01) and 21 times more thickleaf penstemon (P. pachyphyllus; p < 0.001) established when coated with GA(3), but GA(3) coating did not affect the establishment of firecracker penstemon (P. eatonii; p = 1). Establishment was higher from deep furrows than shallow rows (p < 0.001). These results indicate that GA(3) seed coating and deep, U-shaped furrows may improve the restoration success of some native forbs by breaking dormancy and providing a favorable microsite. Land managers could use these techniques to restore native forbs in dry, disturbed areas.

Automated summary

Many plant species have strong seed dormancy, which can impede restoration efforts. This study found that coating seeds with GA(3)-impregnated polymer can overcome dormancy and increase germination rate. Additionally, creating a favorable microsite with increased soil moisture can also mitigate seed dormancy. The research compared the establishment of coated and uncoated seeds under different planting conditions and found that both GA(3) seed coating and deep, U-shaped furrows can improve the restoration success of some native forbs.