Resumo

ORTIZ DOMINGUEZ, Aída  e  CASTILLO, Lorenzo. Break dormancy in seeds of weedy and wild rice populations of Venezuela. Agronomía Trop. [online]. 2007, vol.57, n.3, pp.219-229. ISSN 0002-192X.

In this investigation the break dormancy evolution and emergence to three seed burial depth (0, 5 and 10 cm) in 11 populations of weedy rice (Oryza sativa L.) and 4 wild rice (O. rufipogon Griff y O. latifolia Desv) were evaluated. The populations were named according to their origin. The germination tests were carried out in a germination chamber at temperature of 30 ºC, and the emergence trial in pots with 2.5 kg of soil under greenhouse conditions. We used a randomized completely design with four replications. The results showed that the populations of weedy rice and O. rufipogon broke dormancy between 42 and 70 days after harvest (dah). We found that a major proportion of the evaluated populations (46.6%) germinated (> 80% of germination) at 56 dah. The greater lapse to break dormancy was observed in O. rufipogon (Barinas 10 y Barinas 12). The populations Portuguesa 4 (O. latifolia) did not break dormancy in the time that lasted the experiment. In the burial depth of 10 cm there was not emergence of seedling. The seed buried at 5 cm, compared against the superficial sowing, induced them to a secondary dormancy to populations of weedy rice and wild rice. We found a greater degree of secondary dormancy in Cojedes 3, Portuguesa 7, Portuguesa 9 and Barinas 10. Similar that found in the germination experiment, Portuguesa 4 (O. latifolia) did not emerge at the three evaluated burial depths.

Palavras-chave : Oryza sativa L; Oryza rufipogon; Oryza latifolia; weedy rice; wild rice; break dormancy.