PHYSIOLOGICAL QUALITY OF MAIZE SEEDS HARVESTED AT DIFFERENT MILK LINE STAGES

Aiming at evaluating the physiological quality of hybrid seeds of corn harvestedat different milk line stages after drying and storage, the present work was performed at theUniversidade Federal de Lavras (UFLA) seed laboratory together with Monsanto do Brasil S/A. Seeds of the hybrids Ag-9090, AG-9010, DKB-350 and C-747 produced in the winter of2000 in the towns of Iraí de Minas - MG, Campo Florido - MG, Miguelópolis -SP and Guaíra- SP were utilized. In each field were drawn four rows, where 100 ears were harvested per milk line stage (ML), which are ML2, ML 3, ML 4 and ML 5, displaying, respectively, 25%,50%, 75% and 100% of hardened endosperm were harvested . The ears were transported tothe UFLA seed laboratory where they were sampled for determination of water content ofseeds and next, they had their straws removed and were taken to the experimental dryerswhere they were dried at the initial temperature of 35OC to reach 20% of water content followedby temperature of 42OC to 12% of water content. Tests of germination, electric conductivity,cold test without soil and accelerated aging after drying and after 8 month storage wereaccomplished. After drying, values above 95% in the germination tests and above 85% in thevigor tests were found After 8 months storage lower values of germination and vigor for theseeds harvested at ML-2 for all the hybrids evaluated were observed. The results enabled usto conclude that it is safe to harvest corn seeds from the milk line 3 stage ( ML-3) when theyhave 50% of their endosperm solid and a high physiological quality.