Articles
Photoperiod affects morphology, flower productivity and photosynthesis of forced potted Paeonia lactiflora in greenhouses
Article number
1104_32
Pages
211 – 218
Language
English
Abstract
Paeonia lactiflora is a sun-loving herbaceous perennial.
In winter, when it is forced in greenhouses in northern China, the photoperiod is shorter than in April and May, when it grows outdoors.
To find an appropriate photoperiod for forced P. lactiflora ‘Da Fu Gui’ (DFG) and ‘Tao Hua Fei Xue’ (THFX), 3 different photoperiods were provided by high-pressure sodium lamps as a supplemental lighting (SL) source (at 150-170 μmol∙m-2∙s-1): 9 h/d (control, no SL), 14 h/d (5 h SL) and 18 h/d (9 h SL). Growth and photosynthetic changes were observed and the results showed that photoperiods significantly affected flower productivity, morphology and photosynthesis of herbaceous peonies.
Compared with control, the 14 h/d photoperiod increased the flower productivity of DFG and THFX, the crown breadth of DFG; but under 18 h/d photoperiod, DFG showed lower flower productivity, shorter stems and lower net photosynthetic rate (PN), while the same parameters of THFX were not significantly affected.
Prolonged photoperiod positively affected leaf pigment content in pre- and flowering periods of both cultivars, but leaf pigment content did not directly correlate with the PN. Under 18 h/d photoperiod, PSII maximum potential efficiency (Fv/Fm) of DFG kept a low level, which might be responsible for lower PN. In stem and leaf growth period, prolonged photoperiod also positively affected the leaf soluble sugar and soluble protein accumulation, but in flowering process, the contents changed differently in two cultivars.
So, the mechanism of photoperiod effects on herbaceous peonies was a complex process.
Overall, 14 h/d photoperiod was the best for both cultivars, and photoperiod had greater effects on DFG than on THFX.
In winter, when it is forced in greenhouses in northern China, the photoperiod is shorter than in April and May, when it grows outdoors.
To find an appropriate photoperiod for forced P. lactiflora ‘Da Fu Gui’ (DFG) and ‘Tao Hua Fei Xue’ (THFX), 3 different photoperiods were provided by high-pressure sodium lamps as a supplemental lighting (SL) source (at 150-170 μmol∙m-2∙s-1): 9 h/d (control, no SL), 14 h/d (5 h SL) and 18 h/d (9 h SL). Growth and photosynthetic changes were observed and the results showed that photoperiods significantly affected flower productivity, morphology and photosynthesis of herbaceous peonies.
Compared with control, the 14 h/d photoperiod increased the flower productivity of DFG and THFX, the crown breadth of DFG; but under 18 h/d photoperiod, DFG showed lower flower productivity, shorter stems and lower net photosynthetic rate (PN), while the same parameters of THFX were not significantly affected.
Prolonged photoperiod positively affected leaf pigment content in pre- and flowering periods of both cultivars, but leaf pigment content did not directly correlate with the PN. Under 18 h/d photoperiod, PSII maximum potential efficiency (Fv/Fm) of DFG kept a low level, which might be responsible for lower PN. In stem and leaf growth period, prolonged photoperiod also positively affected the leaf soluble sugar and soluble protein accumulation, but in flowering process, the contents changed differently in two cultivars.
So, the mechanism of photoperiod effects on herbaceous peonies was a complex process.
Overall, 14 h/d photoperiod was the best for both cultivars, and photoperiod had greater effects on DFG than on THFX.
Authors
J. Han, G.J. Huang, T. Wu, X.M. Sun, Yan Liu, R.F. Gao
Keywords
herbaceous peony, illumination duration, supplemental light, chlorophyll fluorescence, gas exchange, soluble protein, soluble sugar
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