Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Germination of an invasive Cenchrus ciliaris L. (buffel grass) population of the Sonoran Desert under various environmental conditions.

Abstract

Cenchrus ciliaris is one of the most important invasive plants in northwestern México and southwestern United States, threatening the conservation of desert and thorn scrub. Our knowledge about the mechanisms that underlie its capacity for invasion is limited. Here, we evaluate the effect of light, temperature, gibberellic acid, osmotic potential, heat shock and experimental fire on caryopses germination from an invader population, exploring the hypothesis that fast germination under a wide range of environmental conditions facilitates survival in a plant species that invades desert environments. Results showed that caryopses of invasive plants were light-indifferent, and germinate under a wide range of temperatures (10°C-40°C). Germination initiates in less than 24 h, reaching a maximum in 3-6 days at 25°C, with lower germination recorded below 15°C. Germination occurred at osmotic potentials ranging from 0 to -1.6 MPa. Some of the caryopses germinated only after the lemma and palea were removed and a fraction did not germinate even after covers were removed, suggesting the existence of physiological dormancy in these caryopses. Other seeds did not germinate even after gibberellins treatment. This variation in dormancy may promote a seed bank, increasing possibilities for persistence in time. Plasticity in germination responses to temperature and osmotic potential, as well as fast germination, might facilitate the invasion of buffel grass in arid and semiarid areas.