Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Factors affecting seed dormancy and germination of Paspalum distichum.

Abstract

California-grown P. distichum seeds incubated at optimum temp. between 28° and 35°C, gave 14% germination in darkness and 40% germination at 16-h day length. The max. and min. limits for germination with light were >45° and 10-22°, resp. After-ripening was accelerated by dry storage of the seeds at 50°. Pre-chilling at 6° and a 2-h heat treatment at 40° had no effect on germination. Gibberellin A3 increased germination only up to 10%. The treatments that caused >40% germination of seeds in the dark were immersion of the dry seeds in conc. sulphuric acid for 30-60 min, giving 60-95% germination; or in 700 msmallcap˜m sodium hypochlorite (NaOCl) for 1-8 h, giving 53-80% germination. The clearest results were obtained by treating the dry seeds with oxidants, sulphuric acid being the most effective, followed by NaOCl and hydrogen peroxide; the latter being effective only in the presence of light. The light-induced stimulatory effect decreased with increasing exposure of dry seeds to both sulphuric acid and NaOCl. However, the light effect was still apparent in imbibed dormant seeds with 2-h NaOCl immersion but not in dry seeds with the same treatment. The results suggested that the seed dormancy in P. distichum was mainly imposed by seed coverings, including hull and seed coat membranes.