Preliminary study shows germination of Caribbean applecactus (Harrisia fragrans) improved with acid scarification and gibberellic acid

Abstract

To determine germination rate and final germination percentage of the endangered Florida endemic Caribbean applecactus (Harrisia fragrans Small [Cactaceae]), we treated seeds with sulfuric and gibberellic (GA₃) acids and germinated them under constant temperature regimes. Temperature effect was marginal at best, with only 2% of seed germinating in 50 d in 25 °C. Although there was improved germination with sulfuric acid (H₂SO₄) alone, significant increases in both germination rate and germination percentage were realized when seeds were scarified with 18 M H₂SO₄ for 15,30,and 45 s,followed by soaking in 1000 ppm GA₃ for 24 h,with 68% germination in 120 d for the 45 s H₂SO₄ treatment. Emergence first occurred on day 18 for seed treated with 1000 ppm GA₃ but not until day 70 for the 500 ppm treatment. Control seeds failed to emerge during the observation period. These treatments represent a quick method of meeting Species Level Recovery Actions for Harrisia fragrans in the Multi-Species Recovery Plans for South Florida.