Seed and germination traits of the summer weed Trianthema portulacastrum L.

Trianthema portulacastrum L. is one of the problematic terrestrial summer weeds. It competes with various agricultural crops. The present investigation aimed to investigate the traits, which enable the seeds to disperse, germinate, grow and adapt to habitat conditions. The plant produces large number (1931 seeds) of small seeds (1.08 mg seed-1). Scanning electron microscopy of the seed testa revealed that the anticlinal walls of the epidermal cells were penta-hexagonal, and highly raised, while the periclinal walls were sunken. This pattern leads to the porous appearance of the testa. The effects of temperature on seed germination were monitored under continuous light and continuous dark conditions. Under light conditions, the percentages of seed germination were significantly higher than at the dark conditions. Higher temperatures of 35, 40 and 45 °C promoted the seed germination. In the temperature range from 30 to 45 °C, the plumule lengths of the seedlings germinated in the light conditions were smaller than those grown under dark conditions. Under all conditions, the length of radicle was higher than the plumule. The traits of seeds, germination, and seedlings grown under experimental conditions are discussed in terms of the seed dispersal and potential adaptations of seedlings to the environment.