Seed heteromorphism can influence germination and ultimately seedling establishment, particularly in disturbed habitats. This study compared seed and seedling traits across three distinctly colored seed morphs (viz. light-brown, brown, and dark-brown) of the forage legume, Teramnus labialis (L.f.) Spreng. The best quality seeds (i.e., un-parasitized, filled and un-cracked) were brown: 389.3 quality seeds per 1000 units compared with <270/1000 units for the other two morphs. Length, width, volume, and water content were lowest in the light-brown and highest in the dark-brown seeds. Seed thickness and mass were lower in the light-brown seeds. Dark-brown seeds imbibed fastest from 2 h onwards. Germination was comparable across the morphs after 7 days but was lowest in the light-brown (17% at 21 days) and highest in the dark-brown seeds (36% at 21 days) at 14 and 21 days. At 7 days, seedling emergence in the dark-brown seeds (15.0%) was higher than in the other two morphs (4%–6%); this remained so at 14 and 21 days. Seedling growth (number of leaves, stem height and diameter, and root length) was superior in the dark-brown seeds. Seed heteromorphism in T. labialis may allow its persistence in disturbed habitats, and the dark-brown seeds are best suited for seeding in revegetation projects, given their superior germination capacity and seedling vigor.

Introduction— The hard seed is the main cause of dormancy in most of the Leguminoseae species. Seed scarification methods, where physical damage is sought to break hard seed coat without diminishing quality, have been modified over time to make them more effective. The most commonly used seed scari- fication methods include heat, mechanical scarifica - tion, and freeze-thaw. Some methods for freeze-thaw scarification include ultra-low temperature immersion in Liquid Nitrogen (LN, –196°C). Objective— Determine the effectiveness use of Liq- uid Nitrogen (LN) as a scarification method to over- come dormancy in seeds of species of the Legumi- noseae family. Methodology— The physiological quality of all freshly harvested seeds was determined and scari- fied by direct immersion in LN for 30 minutes. Total germination was determined under laboratory condi- tions, as well as the time required for the seeds to reach 50% germination (T50) and the total number of seeds that remained hard at the end of the experi- ment. The percentage of emerged seedlings and their vegetative growth was evaluated for 21 days after sowing. Results— The seeds of all species evaluated showed a high physiological quality at the time of harvest. Scar- ification with LN improved germination, emergence and vegetative growth in the species Desmodium scor- piorus, Teramnus labialis, Neonotonia wigthii and Phueraria phaseoloides. Conclusions— Dormancy was effectively overcome in the seeds of the species D. scorpiorus, T. labialis, N. wigthii and P. phaseoloides. It was possible to increase the percentage and speed of germination and emer- gence, managing to obtain plants with greater veg- etative growth during the first 21 days after sowing.