Role of pericarp in the dormancy of sunflower line IMI-3

RIERA, NATALI; VIGLIOCCO, ANA; ANDRADE, ANDREA M.; LINDSTROM, L.; ALEMANO, SERGIO G.

Congreso; THIRD JOINT MEETING OF THE BIOLOGY SOCIETIES OF ARGENTINA; 2015

Sunflower (Helianthus annuus L.) is one of the most widely cultivated oilseed crops in the world, Argentina being one of the world's major exporters of its oil. Sunflowers can display an irregular seed germination due to intrinsic causes which is one of the most important constraints to its commercial production. Such a process, called dormancy, may be the caused by the embryo, the seed coat and/or the pericarp. The pericarp has a complex effect on germination and dormancy as a result of both physical and chemical factors. Sunflower dormancy can be reduced during after-ripening or by removing seed coats. Our objectives were to investigate the role of pericarp in dormancy of sunflower cypselas of the IMI-3 line, and to evaluate the dormancy maintenance during dry storage conditions. The germination test was conducted on dry cypselas with and without pericarp at 42 and 70 days after-harvest. Germination percentage was recorded at 10 days. For the histological analysis, permanent slides of pericarp cross-sections were obtained. In our work, the final germination percentage showed significant differences between cypselas with intact pericarp (42 days after-harvest: 26%; 70 days after-harvest: 77%) and cypselas without pericarp (42 days after-harvest: 65%; 70 days after harvest: 96%). This indicates that dormancy release is related to the duration of the storage period. In addition, pericarp anatomy suggests that the establishment of physical dormancy may be related to the sclerification of the middle layer and the increase in a substance similar to phytomelanin in the rays.