Determining the extent of seed dryer damage in corn (Zea mays L.) seed using the tetrazolium test and other seed quality tests

Abstract

Seed drying is a critical step in hybrid corn (Zea mays L.) seed production. If not performed or monitored closely, seed injury may occur and lead to decreased germination and vigor. The central hypotheses of this thesis are that the severity of dryer damage can be determined immediately following harvest using seed quality tests and that some hybrids are more sensitive to drying than others. Our objectives were to develop a library of photos illustrating evaluation criteria for separating dryer damaged seed into vigor categories; and to estimate the ability of a tetrazolium test to predict a standard germination or vigor test result three months from harvest in seed lots dried using different drying conditions. For each year, samples were harvested, husked, and placed into one of three drying treatments before being shelled for storage. The treatments in year 1 varied from the treatments in year 2. Seed quality testing was done after 0- and 3-months of storage. The standard germination test was used to assess seed viability while the tetrazolium test and the seedling growth rate tests were used to evaluate seed vigor. Data were analyzed by year, since different hybrids were used each year. Our study confirmed previous knowledge that dryer damage significantly decreases hybrid corn seed quality. The decrease in seed corn quality also was associated with seed vigor loss throughout storage time and seed deterioration. The drying rate and the maternal influence on seed were significant factors in determining the extent of dryer damage. The hybrids with a sensitive female parent should be closely monitored while drying artificially. When the tetrazolium test was performed immediately following seed damage (i.e., after 0 months of storage), it was an effective tool for predicting the results from germination and seedling growth rate tests. Those same tetrazolium test results obtained immediately following seed damage (i.e., after 0 months of storage) were not successful at predicting seed germination and seedling growth rate test results after three months of storage. This project advances our understanding of seed physiology related to dryer damage. The information generated can be used to assist seed producers and brokers in assessing potential dryer damage in different seed lots.