Effect of temperature, scarification and light on the dormancy and germination of seeds of three mesquite (Leguminoseae: Prosopis spp.) hybrids naturalized in Australia

摘要

Mesquite (Prosopis spp.) is a Weed of National Significance (WONS) in Australia. Seed dormancy and longevity are key characteristics contributing to the resilience of this noxious weed. We evaluated the requirements for dormancy release and germination of seeds of three mesquite hybrids found in Australia. The hybrids differed significantly in seed weight; P. velutina Woot. hybrid from NSW (56 mg) > 'purple' hybrid from Mar die Station, WA (36 mg) > 'yellow' hybrid from Mardie Station (31 mg). Seedswere incubated at constant temperatures between 15-45°C, and 12-hourly alternating 15/25°C and 25/3 5 °C. After 14 days ungerminated seeds were scarified and monitored for a further seven days. No significant differences between hybrids were found inseed dormancy or germination, despite occurring in quite different climatic conditions. Most seeds (>95%) were viable. Dormancy release, involving the seed coat becoming permeable to water, occurred in more of the seeds as incubation temperature increased. Approximately 80% of seeds remained dormant after 14 days at 15°C, but only 40% were dormant at 40°C. When non-dormant (either naturally or artificially scarified), all seeds germinated at all temperatures tested, except 45°C which resulted in seeddeath.