Effect of light quality on Tabebuia rosea (Bignoniaceae) seed germination

Tabebuia rosea germination capacity and rate have been examined under light and dark conditions. However, seeds responses to light quality, in particular to short and mid-wavelengths, are not well known. We hypothesized that short wavelengths would have a positive effect on T. rosea germination. The effects of short, mid and long-wavelengths on germination capacity, rate (germination rate index, germination rate R₅₀, a devised index of germination rate R₅₀ and peak value), mean daily germination and germination value were evaluated. Light quality had little effect on germination capacity; it was reduced only in darkness. Seeds under short and mid-wavelengths germinated faster (germination rate) than under any other light treatments. We concluded that although T. rosea seeds respond to all light quality treatments, the short and mid-wavelengths are the cue for increasing germination speed. For synchronizing germination, short and mid-wavelengths transmitted by red cellophane paper can be used as a pre-germinative treatment for restoration and silvicultural purposes.