Methods for overcoming dormancy in cassava seeds

Resumo

The propagation of cassava via seminal is an option but faces problems due to dormancy and slow germination. Therefore, the objective was to evaluate the effect of pre-germination treatments, on overcoming Manihot esculenta seed dormancy, clone Gabriela, cultivated in Roraima, Brazil. The experiment was a completely randomized design, with four replicates of 25 seeds, each in seven treatments: intact seeds (CONTROL); lateral scarification the seed (LS); removal of the caruncle (RC); scarification of the caruncle (SC); immersion of the seeds in sulphuric acid for 10 minutes (SA10); for 20 minutes (SA20) and for 30 minutes (SA30). The seeds were sown in trays containing river sand, washed and passed through a 2 mm mesh sieve. The following variables were analyzed: seedling emergence (SE), average emergence time (MET), emergence speed index (ESI), percentage of firm seeds (PFS), percentage of hard seeds (PHS) and percentage of deteriorated seeds (PSDET). The LS (89±7%) and SC (82±5%) treatments were superior to the others, obtaining the shortest MET (11.7±0.38 and 12.8±0.69 days, respectively) and consequently the highest IVE (1.55±0.22 and 1.74±0.22). Sexual propagation of cassava is possible. Lateral scafifying the seeds until the inside of the tegument with exposure of the endosperm with the caruncle intact (LS) and Scarifying the of caruncle until the inside of the tegument (SC) were more efficient seedling emergence and in counting normal cassava seedlings. Soaking seeds in sulphuric acid (AS10; AS20 and AS30) does not overcome the dormancy of cassava seeds.