Germination of Phlox pilosa L. Seeds Is Improved by Gibberellic Acid and Light but Not Stratification, Potassium Nitrate, or Surface Disinfestation

Abstract

<jats:p>The effects of warm stratification and cold stratification, gibberellin-3 (GA<jats:sub>3</jats:sub>) concentration, potassium nitrate concentration, light, and duration of surface sterilization on the germination of downy phlox (<jats:italic>Phlox pilosa</jats:italic> L.) seeds were studied. Germination after 21 days (G21), days to 50% germination (T<jats:sub>50</jats:sub>), and number of days between 10% and 90% final germination (T<jats:sub>90</jats:sub>–T<jats:sub>10</jats:sub>) were calculated for each treatment. Total germination percentage was most significantly improved by cold stratification at 5 ± 2 °C for 10 weeks after warm stratification at 20 °C for 2 weeks; however, a substantial amount of germination occurred during the prestratification period, thus resulting in a crop with poor uniformity. A total of 10 mg·L<jats:sup>−1</jats:sup> GA<jats:sub>3</jats:sub> significantly improved the G21, T<jats:sub>50</jats:sub>, and T<jats:sub>90</jats:sub>–T<jats:sub>10</jats:sub> values. Although GA<jats:sub>3</jats:sub> concentration and duration of cold stratification period interacted significantly when the two were combined, the additive effects of GA<jats:sub>3</jats:sub> and cold stratification did not significantly improve G21 values over those obtained with GA<jats:sub>3</jats:sub> alone nor were T<jats:sub>50</jats:sub> values improved over those obtained with cold stratification alone. Potassium nitrate did not influence the T<jats:sub>50</jats:sub> and T<jats:sub>90</jats:sub>–T<jats:sub>10</jats:sub> values and improved G21 only slightly. Light was found to be necessary for germination. Surface sterilization with 10% bleach decreased the growth of fungi on seeds but had no significant effect on the germination responses of <jats:italic>P. pilosa</jats:italic> seeds. Application of GA<jats:sub>3</jats:sub> at 10 mg·L<jats:sup>−1</jats:sup> is a promising method for improving seed germination in perennial <jats:italic>Phlox</jats:italic> species.</jats:p>

Germination capacity and viability of threatened species collections in seed banks

“…However, contrasting results from the literature (e.g. Okonkwo and Nwoke 1975;Clevering 1995;Chun et al 1997;Madeiras et al 2007) show that sterilisation treatment should be adjusted to each species (in terms of dilution and soaking time).…”