Aspetti tecnici della raccolta di seme in Medicago polymorpha L

Seed harvesting techniques in burr medic (Medicago polymorpha L.). Annual medics (Medicago spp.) are an important group of self-reseeding pasture species originated from the Mediterranean basin. These species were introduced and naturalised in Southern Australia. From this continent, relevant amounts of annual medics seed are currently exported abroad. Conversely, the limited information on the annual medics seed harvesting and an unfavourable context for seed production has limited so far the fully exploitation of the rich legume pasture germplasm in their origin regions. The objective of this research, carried out in Sardinia, was to compare in field traditional and alternative techniques for the seed harvesting of burr medic (Medicago polymorpha L.). The agricultural equipments used were an Horwood Bagshaw vacuum harvester, a traditional combine harvester with cutting bar or pickup, and a pod sweeper, each one requiring different field operations. During the biennium 2005-2007, burr medic "Anglona", the first Italian variety, was established both in pure sward and mixture with triticale and it was grown under the organic agriculture rules. According to the seasonal weather trend, actual seed yield of the legume 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 efficient equipments, leaving on the soil, respectively, about 10 and 30% of the actual seed yields, while the use of combine harvester was not satisfactory even if less complicated and cheaper. Advantages and disadvantages of each seed harvesting systems including the related costs per hectare were evaluated. In addition, the research pointed out that organic seed yield of burr medic is similar to the conventional one but the weed management need to be set up.