Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 2.01

DOUBLE CYCLE IN SUNFLOWER (HELIANTHUS ANNUUS L.) BREEDING

D. LAURETI, A. DEL GATTO

Istituto Sperimentale per le Colture Industriali, Sezione operativa periferica di Osimo, via Torri 26, 60025 Osimo (AN)

sunflower, double cycle, seed moisture, germination, earliness

Intensive breeding of sunflower hybrids involves reaching the use of the lines as soon as possible from the start of the program. It is known that using green houses, in vitro culture and climatic chambers, it is possible to obtain from three to six generations per year according the use of immature embryos, etc. (Marin, 2000). In the absence of the above facilities, until know, only a traditional cycle x year has been done. However the relatively short sunflower cycle and the potential use of immature embryos could allow at least two cycles per year, To verify this possibility, in 2002, an experiment was conducted to test the possibility of obtaining two generations from three hybrids of different earliness (Floralie, early, Gloriasol, medium and Select, late), at three sowing times and four harvestings and consequently sowings of the second cycle. Sowings were done the 4; 15 and 26^th March, harvesting after 12; 24 and 32 days after end flowering and at maturity.

Seed moisture in the first cycle was influenced by cultivar earliness and harvesting time. It was lower in the earliest hybrid and higher in the latest and was proportionally lower in relation to the harvestings (57 vs. 37; 16 and 11%, respectively from 12 days to maturity).

Thousand seed weight was influenced by cultivar, but on the average 74% of the mature weight (37; 47; 49 and 51 g respectively for each harvest) was already reached 12 days from the end of flowering. Seed yield after 12 days was 66% of that at maturity.

Seed germination in the first cycle was influenced by cultivar (9; 33 and 23%) and harvesting time (12; 21; 31; and 26%) and was higher in the latest, even if, at maturity, it was not significantly different from the third one.

Seeds of the second cycle gave plants that reached maturity in all harvestings for all hybrids, but seed germination in the second cycle was 62; 60; 41 and 12% in relationship to the four harvestings of the first cycle and consequently it replantings, showing that in all the combinations tested it was possible to obtain two sunflower cycles per year. Only with the first two harvestings of the first cycle it was possible to have seed germination agronomically acceptable for commercial use certainly due to good weather conditions during maturity.

Marin, I.V. 2000. Helia, 23, 33, 129-134