Articles
EFFECTS OF LOCALIZED LIGHT QUALITY FROM LIGHT EMITTING DIODES ON GERANIUM PEDUNCLE ELONGATION
Article number
580_18
Pages
151 – 156
Language
English
Abstract
We investigated the localized effect of light quality on the morphogenesis of peduncle of geraniums using light emitting diodes (LED). Under metal halide lamp (MH), light from LED; blue (B-LED), far-red (FR-LED) or red (R-LED) was irradiated to the top or upper region on the peduncle, as well as to the top of the main stem of geraniums.
Light intensities of MH and LED were 100 and 50 μmol m-2 s-1, respectively.
Irradiation using FR-LED to the upper part of the peduncle, promoted elongation of the irradiated peduncle, and the length of the peduncle was 15% longer than the mean of plants under MH without LED. However, lighting by R- or B-LED suppressed the elongation of the irradiated part of peduncle.
When cell length of cortex and pith along the vascular bundle was observed on peduncle for the upper part, under local irradiation using FR-LED, mean cell length was about 20 μm longer than one under local irradiation using R-LED. Consequently, the increase of the cell elongation of peduncle under local irradiation by FR-LED induced a longer peduncle.
However, under local irradiation using B-LED, cell length did not change.
Deduced cell number calculated from the data of peduncle and cell length, decreased under local irradiation by B-LED. Decrease of the deduced cell number of peduncle induced a shorter peduncle under local irradiation by B-LED. From those results, the light signal received by the peduncle of the geranium, affected the division or elongation of the cells, and the possibility of consequentially controlling the elongation of peduncle itself was indicated.
This study shows that primary sensor that controls the elongation of the peduncle might be the cell of peduncle in geranium.
Light intensities of MH and LED were 100 and 50 μmol m-2 s-1, respectively.
Irradiation using FR-LED to the upper part of the peduncle, promoted elongation of the irradiated peduncle, and the length of the peduncle was 15% longer than the mean of plants under MH without LED. However, lighting by R- or B-LED suppressed the elongation of the irradiated part of peduncle.
When cell length of cortex and pith along the vascular bundle was observed on peduncle for the upper part, under local irradiation using FR-LED, mean cell length was about 20 μm longer than one under local irradiation using R-LED. Consequently, the increase of the cell elongation of peduncle under local irradiation by FR-LED induced a longer peduncle.
However, under local irradiation using B-LED, cell length did not change.
Deduced cell number calculated from the data of peduncle and cell length, decreased under local irradiation by B-LED. Decrease of the deduced cell number of peduncle induced a shorter peduncle under local irradiation by B-LED. From those results, the light signal received by the peduncle of the geranium, affected the division or elongation of the cells, and the possibility of consequentially controlling the elongation of peduncle itself was indicated.
This study shows that primary sensor that controls the elongation of the peduncle might be the cell of peduncle in geranium.
Authors
N. Fukuda, S. Nishimura, M. Nogi
Keywords
cell elongation, light emitting diode, light quality, Pelargonium zonale
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