Deteriorative changes in primed sweet corn seeds during storage

Solid matrix priming offers an effective mean for raising seed performance in sweet corn (Zen mays L.) carrying the shrunken-2 (sh-2) gene. Nevertheless, the storability of primed sh-2 seeds is still unknown. The present study was undertaken to investigate the emergence performance of vermiculite-primed sh-2 seeds of two hybrids during 12 months of dry storage. Several physiological traits in relation to lipid peroxidation and peroxide-scavenging were also examined. The results indicated that vermiculite priming improved seedling emergence, decreased initial seed leakage, reduced lipid peroxidation and enhanced activities of several peroxide-scavenging enzymes. However, the benefits of priming were diminished and the longevity was shortened when primed seeds were stored for 12 months, especially under 25 degrees C storage conditions. The loss of viability might be linked to the increased seed leakage (after 12 months of storage) and lipid peroxidation, marked changes in peroxide scavenging activities and the shift of glutathione redox status toward a more oxidized form. Significant differences also existed between hybrids in emergence percentage and related physiological activities, although the responses expressed as a function of storage duration are rather similar. It appears that the priming effects on sh-2 corn seeds can be maintained after storage for 6 months under 10 degrees C. However, the primed sh-2 seeds deteriorated more rapidly than non-primed sh-2 seeds when stored at 25 degrees C for 6 months