Dehulling the secret of the germination of crop wild relatives of Cenchrus , Digitaria , Echinochloa , Setaria and Urochloa

Wild grass species (family Poaceae) of the genera Cenchrus , Digitaria , Echinochloa , Setaria and Urochloa , are widely conserved in seedbanks as important tropical forages, wild collected cereals and wild relatives of millets. The lack of knowledge on germination requirements and dormancy-breaking methodologies limits the conservation and use of these seedbank accessions. We present the results of germination experiments on 24 accessions belonging to 14 different species of these genera, considering both accessions conserved under long- term storage conditions for up to 43 years as well as freshly collected material. Different treatments were tested: (1) germination of intact dispersal units at 30/20°C; (2) germination of dehulled caryopses at 30/20°C; (3) germination of intact dispersal units at 25°C; and (4) germination of dehulled caryopses at 30/20°C with 250 mg L -1 GA 3 solution. Alternating temperatures promoted the germination of 18% of the tested accessions. Dehulling the caryopses enhanced the germination of 83% of the accessions, for 83% of the tested accessions caryopsis extraction coupled with the use of GA 3 further improved final germination. Overall, germination > 70% was obtained for 22 of the 24 tested accessions. The presented results can improve the management of seedbank accessions of these economically important crop wild relatives.