Dormancy breakage and germination are tightly controlled by hypoxic submergence water on Echinochloa crus-galli seeds from an accession resistant to anaerobic germination

JULIANA ECHEVERRY HOLGUÍN; MARÍA A. CREPY; GUSTAVO G. STRIKER; FEDERICO P.O. MOLLARD

SEED SCIENCE RESEARCH

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2020

0960-2585

In wetlands, dormancy may be a key functional trait enabling seeds to avoid underwater germination, which could be lethal for seedling establishment. Our objectives were to find out (i)if shallow dormant (i.e. conditionally dormant) Echinochloa crus-galli seeds from an anaerobic germination resistant accession can break dormancy under hypoxic submergence and(ii) if underwater germination can be restored in scarified, non-dormant seeds. Shallow dormant E. crus-galli seeds perceived diurnally alternating temperatures (AT) and red light (R)pulses (i.e. dormancy-breaking cues) under hypoxic submergence; however, an inhibitoryfar-red light pulse given at the end of the 4-d inundation period demonstrated that most ofthe seeds (85%) were unable to break dormancy. Scarified E. crus-galli seeds, which did notexpress dormancy under drained conditions, were unable to germinate under hypoxic submergence, despite being exposed to dormancy-breaking cues (AT + R). Lastly, the temporalwindow for germination sensitivity to the inhibitory action of hypoxia, once dormancy-breaking signals have been applied, is progressively lost and bounded to approximately 18 h for halfof the seed lot. These results highlight the importance of dormancy as a trait enabling E. crusgalli seeds to avoid underwater germination, a risky scenario for seedling emergence andestablishment in this facultative hydrophyte.