Effect of Seed Storage Environment on Sea Oats (Uniola paniculata) Germination

Beach restoration is essential in the northern Gulf of Mexico coast due to high rates of coastal erosion. Sea oats (Uniola paniculata), a native perennial grass of the southern Atlantic and northern Gulf of Mexico coasts of the United States, builds and stabilizes sand dunes, which buffer storm surge and protect coastal communities and infrastructure (Wagner 1964, Seneca 1972). To produce sea oats plants for beach restoration, seeds are often collected from natural populations and grown in greenhouses until large enough for planting. Significant work has investigated the effects of light, temperature, and stratification on sea oats seed germination. Alternating temperatures yield the highest germination (Seneca 1969, Seneca 1972, Hester and Mendelssohn 1987) and light is not required for germination (Westra and Loomis 1966, Burgess et al. 2002). Response to cold stratification varies. Sea oats seed produced in Virginia and North Carolina have higher germination after cold stratification (Seneca 1969, Seneca 1972, Burgess et al. 2002), while seed collected from Florida's Atlantic coast are unaffected by cold stratification. Seneca (1972) also found that seeds collected from the northern Gulf of Mexico coast have an intermediate response while Hester and Mendelssohn (1987) found that seeds collected from Louisiana germinated faster after cold stratification.

To support sea oats restoration efforts, reduce the frequency of seed harvests that cause physical disruptions to natural ecosystems, and strengthen sea oats genetic conservation, additional work is needed. Seed germination is known to be affected by seed storage conditions, moisture content, and pathogens (Copeland and McDonald 2001, Elias et al. 2007, Elias et al. 2012); however, there are only limited accounts of sea oats seed pathogens (Hester and Mendelssohn 1987, Burgess et al. 2002). Information on

Table 1.

Storage environments and conditions of sea oats seed harvested in September 2010 from a seed production nursery at Long Beach, MS.

how long seeds must remain in germination conditions to achieve high germination percentages is also limited; most studies investigated germination for specific time periods (Seneca 1969, Seneca 1972, Hester and Mendelssohn 1987, Burgess et al. 2002). Germination period is essential for planning and implementing beach restoration projects. The objectives of this study were to: (1) examine effect of storage environment, specifically, storage temperature and container on sea oats seed germination; (2) determine the length of time necessary for sea oats seeds to germinate; (3) examine sea oats seed moisture content; and (4) determine seed pathogen incidence during germination.

We harvested mature sea oats panicles in September 2010 from a seed production nursery established in a natural beach environment at Long Beach, MS. Seeds were threshed from panicles with a forage belt thresher (Agriculex Inc., Guelph, Ontario) and placed into six storage environments (Table 1) in December 2010. Environments were selected to simulate commercial storage. From January 2011 to December 2011, 200 seeds (8 replicates of 25 seeds) were removed from each environment every 28 days. We used the oven method to determine seed moisture content (Elias et al. 2012). We surface sterilized sea oats seeds with 25% Clorox for 15 minutes (Woodhouse et al. 1968) prior to placement onto germination paper moistened with distilled water (ISTA 2008). We germinated seeds in the dark at 18.3°C for 17 hours and at 35°C for 7 hours (Woodhouse et al. 1968).

Every 7 days we examined seed germination and pathogen incidence for 35 days after planting. A seed was considered germinated when the radicle was greater than 2 mm; seeds infected with pathogens were removed. Percentage germination was calculated for 21, 28, and 35 days after planting as: (number of germinated seed at dχ / (number of seed planted—number of infected seed)) × 100, where dχ is the number of days seeds were in the germination environment. Total percentage seed germination was calculated as: (total number of germinated seed / (total number of seed planted—total number of infected seed) × 100. Percentage pathogen incidence was calculated as: (number of infected seed / number of seed planted) × 100.

Table 2.

Average total percentage seed germination, moisture...