| Photosynthetic photon flux density (PPFD), photoperiod and spectral distribution play important roles in regulation of plant photosynthesis and morphogenesis during plant tissue culturing. Plant tissue culture mainly depends on electric light source, which has low bioenergy efficiency and high calorific capacity, and its electricity comsuption acount for 65% of the whole power expenditure, that is one of the non-human costs in plant tissue culture. Using light emitting diode as light source in plant tissue culture to regulate light quality and PPFD can not only regulate the plant growth and development and morphogenesis, but also reduce energy comsumption remarkbly, and decrease the cost accordingly. Besides, it solves the weakness of light quality impurity, and increases the reliability of experiment results.The test-tube plantlets of grape variety Beta and Vitis piasezkii Maxim were used as the material in this experiment, and their dynamic growth, propagation of the aboveground parts (plant height, leaf size, biomass, internode length and stem diameter) and underground parts (root weight, root numbers, root length and root diameter), pigment content, stoma and enzyme activity were studied with LEDs irradiation (white, red, yellow, blue and green) on four photoperiods (24 h·d-1,16 h·d-1,12 h·d-1,8 h·d-1), so as to get the optimum LED light quality and photoperiod to the plantlets growth.The results are as follows:1. Red LED was favorable to the longitudinal growth of the plantlets aboveground and underground parts, however, blue LED had opposite effect, but promoted their cross growth; blue-red LED was better than ordinary fluorescence to increase photosynthetic rate of the plantlets. Red, blue and blue-red LEDs enhanced the biomass obviously with 16 h·d-1 irradiation; the stem nodes were the thickest under blue and blue-red LEDs with 24 h·d-1 irradiation.2. Yellow, green LEDs with 16 h·d-1,12 h·d-1 irradiation were favorable to increase plant height; blue and blue-red LEDs with 16 h·d-1 were benefit to leaf size increase, but the leaf size was smaller under green and yellow LEDs with 24 h·d-1 irradiation. The internodes were longer under green and yellow LEDs, but the shortest under blue LED; the stem nodes were the thinnest under green and yellow LEDs with 8 h·d-1 irradiation; the root was the thinnest under yellow LED with 16 h·d-1 irradiation; however, the photosynthetic rate was the maximum under blue-red LED, but showed negative value under yellow and green LEDs.3. With each LED and photoperiod irradiation, it was showed that the bigger the stomatal frequency is, the smaller the length X width of the stomata is. The different genotypes needed different LED and photoperiod:the stomatal frequencies of Vitis piasezkii Maxim and Beta were the biggest with blue,16 h·d-1 irradiation and blue-red 24 h·d-1 irradiation, respectively. Red, blue, blue-red LEDs were suitable to chlorophyll synthesis, but 8 h·d-1 was inferior to the other three photoperiods to synthesize chlorophyll; light quality and photoperiod effect varied due to different genotypes. SOD activities were the highest under blue LED, but the lowest under red LED, and the activity of Beta plantlet was the highest with 8 h·d-1 irradiation, the lowest with 24 h·d-1 irradiation; but that of Vitis piasezkii Maxim was the highest with 16 h·d-1 irradiation, the lowest with 12 h·d-1 irradiation. The order of PPO,POD and CAT activities in test tube plantlets were all 24h.d-1>16 h.d-1 >12h.d-1>8h.d-1。... |
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