Effect of Scarification Method and Storage Time On Hard Seed and Germination of Forage Legumes.

Producers in the Central West regions of USA are interested to grow sainfoin, cicer milkvetch, and winter annual medic in addition to alfalfa.  However, hard seeds and low germination make them difficult to establish in the field for many instances.  The objective of this study is to reduce hard seed and improve germination of these forage legumes through seed scarification and storing.  Scarification study was conducted on the seeds of three cultivars (‘Ranger’, ‘Ladak’, and ‘Vernal’) of alfalfa, yellow flower alfalfa, three cultivars each of sainfoin (‘Shoshone’, ‘Eski’, and ‘Remont’) and CMV (‘Monarch’, ‘Oxley’, and ‘Lutana’), and one cultivar (‘Laramie’) of winter annual medic.  Four scarification methods utilized included heat (60°C in an oven), freeze-thaw (temperature alternations between -80°C and 22°C), acid (soaked in concentrated sulfuric acid), and mechanical (rubbed with a sandpaper) scarification.  The experimental design was a RCD with five replications.  The seeds treated with heat and freeze-thaw scarification were stored for eight months at two temperature regimes (22°C and 8°C).  Hard seed of all alfalfa and sainfoin seeds was low (0-9%) while germination was high (88-100%) in untreated control indicating no harmful effect of scarification on seed viability.  Mechanical (20 min) and acid (5 min) scarification decreased hard seed and increased germination of CMV (Monarch: 70 vs. 27% in control to 1 vs. 98%) and medic (Laramie: 23 vs. 77% in control to 1 vs. 99%), respectively.  Storing seeds at 8°C reduced hard seed (Monarch: 81% before storing to 49% after storing) and improved germination (Monarch: 11% before storing to 51% after storing) in CMV seeds.  No effect was observed in medic seeds after storing (hard seed: 26-33%, germination: 67-74%).  Overall, mechanical scarification and storing reduced hard seed and improved germination in CMV, while acid scarification worked best for medic seeds.