Effect of artificial drying upon the germination of seed corn

The timely artificial drying of seed corn with heated air under forced draft may remove the hazard of freezing injury and facilitate early harvest, storage, and processing. If suitable procedure is followed, no injury results to viability or field performance of the seed. In connection with such artificial drying, a reduction in the moisture content of the seed to 12 to 13% at a temperature range of 105 degrees to 110 degrees F is recommended except that the temperature be held as low as 105 degrees F when the initial moisture content approaches 50%. Prolonged drying at safe temperatures to a moisture content as low as 5% is not harmful to the seed. Such thorough desiccation is impractical, however, as it involves needless expense and time and causes inconvenience when bagged for storage in weighed quantities by gradual increase in weight through absorption of atmospheric moisture. Likewise, insufficient drying subjects the seed to later loss of weight and possible deterioration during storage. The permissible range of moisture content for safe processing and storage approximates 5 to 14%. The length of drying interval needed to reduce ear corn to a safe moisture content varies with the initial moisture content of the grain and the drying temperature. Such duration may approximate 1, 2, or 3 days for corn containing 20, 30, and 50% moisture, respectively, provided the air is sufficiently changed. There appears to be an inverse relation between drying temperature and minimum moisture content attained by the dried seed. After five days of drying at a temperature of 112 degrees F, the moisture approximated 5% while at 107 degrees F it was about 6.5%. It appears that little further desiccation would occur from prolonged exposure at these temperatures. A lot of seed ears dried for 35 days at 107 degrees F contained 4.3% moisture and germinated 98%. Seed with an initial moisture content up to 30% and reduced to as low as 5% by artificial drying for 5 days at 112 degrees F showed no unfavorable stand or seedling growth effects when planted in the field. At a drying temperature of 112 degrees F no significant differential injury was found among 26 representative hybrids ranging in moisture content from 16 to 38%. It would seem possible that among hybrids differing greatly in moisture content at the time of drying, those with excessive moisture would be injured. This would not necessarily suggest heritable difference in heat susceptibility, and might be associated solely with moisture content.