Seed Treatments Enhance American Elderberry Germination

Abstract

Sexual propagation of American elderberry [ Sambucus nigraL. subsp. canadensis(L.) Bolli] can be difficult without specialized handling and storage of seeds after fruit harvest. A study was conducted to evaluate the effect of 3% hydrogen peroxide (H ₂O ₂), GA ₄₊₇(Provide®) at 250 mg·L ^-1, dilute sulfuric acid [1 H ₂SO ₄: 1 tap water (v/v)], and periods of cold stratification (90 and 150 d) on percent shoot emergence and mean days to shoot emergence of ‘Bob Gordon’ and ‘Ozark’ elderberry seeds. Seed soaking treatments included H ₂O ₂for 15 min; GA ₄₊₇for 24 h; H ₂O ₂followed by GA ₄₊₇; H ₂SO ₄for 30 s; and tap water for 15 min before cold stratification at 4°C for 150 d. Two additional treatments included H ₂O ₂or no H ₂O ₂before 60 d at 21 °C followed by 90 d stratification at 4°C. For both cultivars, seed treated with H ₂O ₂, followed by GA ₄₊₇, and cold stratified for 150 d had the highest percent shoot emergence (94%) when compared with other treatments. The same treatment without H ₂O ₂had greater shoot emergence (84%) than seeds that were soaked in tap water and cold stratified for 150 d (72%). Percent shoot emergence for seeds soaked in either treatment of H ₂O ₂, and then maintained at for 60 d at 21 °C before 90 d cold stratification, and those soaked in tap water before 150 d cold stratification were similar. Scarified seeds (i.e., H ₂SO ₄treatment) failed to produce shoots. For both cultivars, seeds treated with GA ₄₊₇had the fewest mean days to shoot emergence (11 to 15 d). In contrast, ‘Bob Gordon’ seeds soaked in tap water and cold stratified for 150 d required fewer days for shoot emergence (21) than ‘Ozark’ (25). Although sexual propagation of elderberry has been considered difficult previously, all treatments used in this study, except for H ₂SO ₄, had over 70% shoot emergence. However, very high germination can be achieved by using a disinfectant on fresh seed followed by a GA ₄₊₇soak for 24 h, and cold stratification before seeding.