|
|
|
| Authors: |
S.F.R. Rocha, F.C.M. Chaves,
L.C. Ming, F.M. Scarda |
| Keywords: |
Ocimum gratissimum,
seed germination, photoequilibrium, photoblasty, light quality,
ecophysiology, medicinal plants. |
Abstract:
Ocimum gratissimum seed
germination (% germination and vigor) has been found as phytochrome
dependent, having a typical High Irradiant Response (HIR). Seven
treatments were tested: daylight (DL), red (R), far-red (FR), blue
(B), green (G), dark (DK), and reversible (RVB). No statistical
difference among the DL, R, FR, B, and G were found. DK and RVB were
statistically equal and presented the lowest results. The
germination also occurred in the DK treatment but in non-useful
rates, and it was nonreversible in the RVB treatment. It allows
these seeds to be classified as positively photoblastic. The minimum
energy need to initiate the germination was evaluated by a
fluency-response curve. It plotted four different exposition times
to R light (1 second, 60 seconds, 1 hour, and 13 hours) against
percent germination. Useful germination occurred only after 1 hour,
confirming the high energy needed to incite the process. The
germination rate increased with the raise of the photoequilibrium
( SEEDS UNDER HIGH IRRADIANCE CONDITIONS_files/phi.lc.gif) ).
The high positive correlation index found confirms the phytochrome
influence in this process. Facing all the results presented here, it
is suggested to sow these seeds under direct and highly intense
sunlight. It is preferable to avoid places exposed to variations in
the shading, because inhibition induced by dense shade effects (low
R/FR ration and consequently low
established) were demonstrated irreversible, and it can lead to
undesirable loss of the germination power.
|
|
Download Adobe Acrobat Reader (free software to
read PDF files) |
 SEEDS UNDER HIGH IRRADIANCE CONDITIONS_files/previous.gif)  SEEDS UNDER HIGH IRRADIANCE CONDITIONS_files/up.gif)  SEEDS UNDER HIGH IRRADIANCE CONDITIONS_files/next.gif) |
