Dormancy Breaking of Teramnus labialis (L.f.) Spreng Seeds Is Affected by the Extent of Liquid Nitrogen Exposure

Teramnus labialis (L.f.) Spreng shows dormancy as a result of impermeability of the seed coat, which requires scarification treatment before sowing. Liquid nitrogen (LN) as a scarifying treatment has recently been used on this species, with excellent results. However, moisture content and immersion time on LN are factors that may affect seed germination and dormancy break. This report studies (i) the effects of dehydration on T. labialis seed viability and germination and (ii) the appropriate moisture content and extent of LN to make this scarification an effective treatment. Moisture contents of 4%, 6%, 8%, and 10% fresh weight basis (FWB) and extension to LN for 15, 30, 45, and 60 min were performed. Seed viability did not change after seed dehydration up to a moisture content of 4% FWB, whereas the percentage of germination decreased as a result of increasing the percentage of hard seeds. The seed moisture content did not affect germination after immersion in LN, but at least 30 min of exposure was required for dormancy break. The mean germination time, germination index, and time to 50% germination improved with the increasing germination from 33% to 91% and a greater duration of immersion in LN. The dormancy of T. labialis seeds with a moisture content between 4% and 10% FWB was only broken when exposed to LN for 30 to 60 min.