SUBSTRATE MOISTURE LEVEL GOVERNS THE GERMINATION OF VERBENA SEED

Verbena (Verbena x hybrida Voss) seed germination varied with the water content of the substrate. Total germination percentages (G) were highest when substrates were 75% to 100% saturated and progressively declined with increased free distilled water (FDW) on the blotter paper substrate. Natural differences in G among cultivars at favorable substrate moisture levels increased when free water was present. Removing the seed hilums did not increase G of 'Romance Scarlet' on a substrate with FDW, but significantly increased the G of 'Showtime Blaze' and 'Red A'. An inverse relationship was found between seed moisture contents and G at high substrate moisture levels. 'Romance Scarlet', 'Showtime Blaze', and 'Red A' had 64%, 73%, and 84% seed moisture contents and G of 72%, 18%, and 10%, respectively. The period of sensitivity to excessive water during germination was day 2 for 'Red A' and days 2 and 3 for 'Showtime Blaze'. The G of 'Romance Scarlet' seed was not reduced when placed on a substrate containing FDW for 1 day. Removal of seed hilums from 'Red A' significantly increased G during day 2 for seeds on a substrate containing FDW.