Biology of tropical weeds is still mostly unknown, especially in relation to facts that could be used as cultural tools for weed management. The present work was aimed at evaluating the infuence of temperature and light on germination of Alternanthera tenella seeds. Treatments consisted of four constant temperature regimes (20, 25, 30 and 35 ºC) in absence of light, and constant temperature of 25 ºC in the presence and absence of light. The germination test was conducted with four replicates of 100 seeds per treatment, placed in plastic boxes (gerbox) and kept in BOD Germinator. Germination evaluations were performed at the same time daily, by counting normal seedlings, with visible roots and cotyledons. Total germination and speed of germination velocity index (GVI) were calculated after 34 days and the experiment was run twice. Total germination and germination velocity increased as temperature increased up to 28.2 ºC, decreasing from this temperature on. At 25 ºC, germination and GVI of joyweed seeds increased when the seeds were kept under light.
calico plant; seedbank; germination test
