Aspetti tecnici della raccolta di seme in Medicago polymorpha L

Seed harvesting techniques in burr medic (Medicago polymorpha L.). Annualmedics (Medicago spp.) are an important group of self-reseeding pasture speciesoriginated from the Mediterranean basin. These species were introduced andnaturalised in Southern Australia. From this continent, relevant amounts of annualmedics seed are currently exported abroad. Conversely, the limited information on theannual medics seed harvesting and an unfavourable context for seed production haslimited so far the fully exploitation of the rich legume pasture germplasm in theirorigin regions. The objective of this research, carried out in Sardinia, was to comparein field traditional and alternative techniques for the seed harvesting of burr medic(Medicago polymorpha L.). The agricultural equipments used were an HorwoodBagshaw vacuum harvester, a traditional combine harvester with cutting bar or pickup,and a pod sweeper, each one requiring different field operations. During thebiennium 2005-2007, burr medic "Anglona", the first Italian variety, was establishedboth in pure sward and mixture with triticale and it was grown under the organicagriculture rules. According to the seasonal weather trend, actual seed yield of thelegume pure sward reached 625 in the first year and 375 kg ha-1in the second one.The vacuum harvester and the pod sweeper proved to be the most efficientequipments, leaving on the soil, respectively, about 10 and 30% of the actual seedyields, while the use of combine harvester was not satisfactory even if lesscomplicated and cheaper. Advantages and disadvantages of each seed harvestingsystems including the related costs per hectare were evaluated. In addition, theresearch pointed out that organic seed yield of burr medic is similar to theconventional one but the weed management need to be set up.