Expurgo, com brometo de metila, de sementes de milho com diferentes teores de umidade

Bacchi, Oswaldo

doi:10.1590/S0006-87051962000100076

Oswaldo Bacchi

SUMMARY

Corn seeds of the Hybrid Hd. 6999 and of the Azteca variety with 11, 13, 15 and 17% moisture contents, approximately, were fumigated with methyl bromide, using a dose of 28 cc of this gas per cubic meter in a sustained vacuum of 58 centimeters for a period of four hours.

Fumigated and non-fumigated seeds with these four different levels of moisture contents were, then, stored in. open and air-tight containers and periodically examined for germination capacity, moisture content, and insect damage, during a period of 12 months.

According to the results obtained, the following conclusions were drawn:

1) the fumigation was found to be effective against Sitophilus oryzae L., at least in the adult stage;

2) germination tests made immediately after the fumigation showed that even the seeds with higher moisture content were not injured by the treatment;

3) excepting the hybrid seeds with 15.1 and 17.2% of initial moisture contents, all the fumigated seeds stored in open containers maintained their vitality for a period of 5 months, while the non-treated hybrid and Azteca seeds had this period of longevity reduced to 3 months and 1 month, respectively;

4) the insect reinfestation of the seeds in this storage conditions occurred exactly in the same way as mentioned above for the seed vitality;

5) in the hermetically sealed containers there was noted a negative effect of the fumigation on the seed longevity, except for the seeds with the lowest moisture content;

6) in this type of container the infuence of the moisture content on the seed viability was clearly observed in both treated and non-treated seeds, and any of these seeds were insect reinfested.

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Recebido para publicação em 23 de maio de 1962