Percussion as an alternative scarification for New Mexico locust and black locust seeds

Abstract

Hot water and sulfuric acid soaks are traditional treatments for seeds of many temperate woody legumes, including locusts. However, these scarification techniques often produce inconsistent germination. Percussion scarification, where seeds are repeatedly propelled against a hard surface, was compared with hot water scarification to evaluate treatment efficacy for New Mexico locust (Robinia neomexicana) and black locust (R. pseudoacacia) seeds. In the hot water treatment, seeds were placed in a 98° C water bath, which was immediately removed from the heat source. For percussion scarification, seeds were placed in a soil sample tin and agitated in a paint shaker for 1, 2, 3, 4, 5, or 10 minutes. All treatments, including the control, were followed by 24-hour water soaks. Hot water baths resulted in 56% and 41% germination for New Mexico locust and black locust respectively. For both species, nearly all durations of percussion increased germination over the hot water treatment. Percussion durations of 4, 5, and 10 minutes for New Mexico locust and 3, 4, and 5 minutes for black locust resulted in at least 90% germination. Traditional scarification treatments randomly degrade the entire seed coat, which can lead to tissue damage during water uptake. Percussion scarification specifically weakens the strophiole, the natural source of water entry to the seed in papilionoid legumes. Following percussion, inhibition is controlled through the strophiole and underlying tissue is protected.

Parent Publication

• National proceedings: forest and conservation nursery associations-1999, 2000, and 2001

Citation

Khadduri, Nabil; Harrington, John T.; Rosner, Lee S.; Dreesen, David R. 2002. Percussion as an alternative scarification for New Mexico locust and black locust seeds. In: Dumroese, R. K.; Riley, L. E.; Landis, T. D., technical coordinators. National proceedings: forest and conservation nursery associations-1999, 2000, and 2001. Proceedings RMRS-P-24. Ogden, UT: U.S. Department of Agriculture Forest Service, Rocky Mountain Research Station. p. 309-316