Innovative strategy to obtain F1 hybrids of globe artichoke

In the Mediterranean basin, where globe artichoke was originated and over the centuries grown, production has increased by 32% in the last 50 years even if without important innovations for the variety and nursery development. Despite this increase, only limited breeding programs have been carried out and inbreeding depression has discouraged such work. Seed lines have been produced and are available in the fresh market, but quality and uniformity problems have prevented consumer's acceptance. At present, the only real novelty could be represented by the development of seed propagated F1 hybrids. During five years of an Italy-California joint research program, an innovative strategy of F1 hybrid constitution was developed thanks to the use of male sterile clones. In order to set up an effective pollination technique for producing F1 hybrids, different systems (brush, bumble bees, honey bees and cutter bees) have been studied under tent and compared with the open pollination control. For the insects, the results highlighted interesting potentialities of bumble bees, in Italy, and honey bees or cutter bees, in California. Starting from the three male sterile clones developed in Italy, other male sterile parents have been identified and multiplied by micropropagation. Fertile homogeneous lines have been obtained by selfing and sibcrosses and maintained both under field and in vitro culture conditions. At least 200 cross-combinations were made and Romanesco hybrids, uniform for head quality and adapted to Italian and Californian environments, have been selected. One of these hybrids, named 'Romolo', is under official evaluation for registration in the Italian varietal list.