Effects of Different Production Systems on Seed Hardiness of Annual Medic (Medicago scuttelata var. Rabinson)

Seed hardiness in annual medics plays an important role in soil seed bank reserve to ensure ley farming system sustainability. To study the level of seed hardiness in annual medic (Medicago scuttelata var.Rabinson) at different fertilizing treatments and growing conditions (irrigated and dry farming system), an experiment was conducted at two research stations (Sararod, Research Institute and Soil Fertility Research Station in Mahidasht). After the physiological maturity of pods in early July, seed germination tests were conducted at 30 days intervals in consecutive months of July, August, September, October, November, December, January and March. Results indicated that seed hardiness decreased after seed maturity and the lowest of seed hardiness was detected in September. Mean monthly hard seed break down rate was lower under irrigated system compared to dry farming system. The mean monthly hard seed breakdown rate was lower in plots receiving biologic and integrated fertilizers compared to other fertilizing treatments. The monthly hard seed break down rate in Sararoud Station (dryer climatic conditions) was higher compared to Mahidasht Station (more annual rainfall and cooler climatic conditions). The highest hard seed rate in dry farming system was obtained in control treatment. However, the highest seed hardiness in irrigated system was observed in nitrogen fixing bacteria + mycorrhiza and nitrogen fixing bacteria + phosphate solubilizing bacteria treatments, respectively.