An alternative model to predict corn seed deterioration during storage

An assumption of the Ellis-Roberts viability equation, that all seed lots o f a species deteriorate at the same rate in the same storage environment, w as not valid for hybrid corn (Zea mays L.) seed. Thus, an alternative model was developed that used a potential storability index (PG, the time for ge rmination to decline to a level G) and a storage environment coefficient (S EC, the factor by which seed longevity is altered by a change in storage te mperature and seed moisture content) to predict deterioration of hybrid cor n seed. The alternative model was derived from the ratio of seed longevity of the same seed lot in two storage environments. The PG in the storage env ironment was estimated as the product of P-G in a rapid-aging test and SEC, which was determined with a regression model based on the differences in t emperature and moisture between the two environments. The model was evaluat ed by predicting the time to 90 and 50% germination (Pw and P-50) for high- and medium-quality seed lots stored under a range of constant conditions. There was generally good agreement between predicted and observed Pw and P- 50, with many of the predicted values within 10% of observed values across five seed Bets. The storage conditions in the rapid-aging test had no effec t on the predictive ability of the model. This model provides an effective approach to predicting corn seed longevity that may be useful in managing s eed storage.