Structural aspects of seed dormancy in quinoa (Chenopodium quinoa willd.): importance and possible action mechanisms of seed coats

CECCATO, D.; BERTERO, H. D; BATLLA, D

Costa do Sauipe

Congreso; 10th Conference of the International Society for Seed Science; 2011

International Society for Seed Science

This study presents results of experiments conducted to establish the importance of seed covers in the maintenance of dormancy in quinoa, and to reveal some possible mechanisms of action and its association with changes in dormancy level caused by the environment. Two quinoa accessions, Chadmo and 2-Want, both showing varying degree of dormancy at harvest, were cultivated in the field on three different sowing dates. Seed were exposed to different treatments and incubated in water at 5, 10 and 25 ºC to check germination. A rapid exit from dormancy was observed in both accessions when seed covers were perforated before incubation. This dormancy-releasing effect of perforation decreased with delayed sowing date, and seeds harvested from late sowing dates expressed a level of dormancy that was not imposed by the seed coat, so presence of embryo dormancy is reported in the first time in the Chenopodium genus. Seeds of accession 2-Want had covers (episperm) significantly thinner in later sowing dates. This was in agreement with decreasing coat-imposed dormancy. In perforated seeds more ABA was leaked out than in whole seeds. The response of germination and the higher amount of ABA released in perforated seeds suggest as hypothesis that a block to the release of the embryo ABA participates in the imposition of dormancy by covers in quinoa. Evidence that some ABA is able to diffuse to the medium even in seeds with intact episperm suggests that differences between sowing dates in the thickness of the episperm, as observed for 2-Want seeds, would allow the release of different amounts of ABA.