Hydration-Dehydration Treatments to Protect or Repair Stored ‘Karamu’ Wheat Seeds
- Suresh Nath,
- Peter Coolbear and
- John G. Hampton
Although presowing hydration treatments are known to be capable of improving the germination performance of wheat seeds, no comprehensive information is available, especially with regard to the effectiveness of such treatments on seeds subjected to deterioration under different conditions. This study reports an attempt to understand the responses of a single high-quality seed lot of wheat (Triticum aestivum L.) to two different storage regimes (100% relative humidity, 40 °C for up to 6 d or at a constant seed moisture content of 0.15 g H2O g−1 fresh weight at 35 °C for up to 50 d). At the same time the relative abilities of three presowing hydration-dehydration treatments to protect or repair the deteriorating seeds were compared. Although losses of viability and increases in radicle emergence rates followed a similar pattern for both regimes, assessments of electrical conductivity of seed leachate and seedling growth indicated that the mechanisms of deterioration varied under the two aging conditions. A 2-h prestorage hydration treatment at 25 °C followed by drying allowed maintenance of germinability in storage, but only had marginal effects when applied after aging. Longer hydration treatments (24 h at 15 °C in water or 20 h at 20 °C in −0.37 MPa polyethylene glycol solution) applied after storage were effective at restoring germination rates of seeds that remained viable. if applied before storage, however, these two treatments severely increased the seeds' susceptibility to deterioration. These results demonstrate that (i) not all aspects of deterioration in wheat seeds are irreversible, and (ii) losses of seed vigor and viability are not necessarily features of the same continuum of deteriorative metabolism. Such combinations of treatments and storage conditions should provide useful systems for the systematic study of deteriorative metabolism in aging wheat seeds.
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