| Light is a necessary environment factor for plant growth, which affects plant growth mainly through the light quality and light intensity. Light has not only provided the energy for plant, but also is an environmental signal regulating plant growth, morphogenesis, photosynthesis, physiological responses, and gene expression and so on. The new light source of light-emitting diode (LEDs) has many unique advantages:wavelength specificity, small size, long life, cold light source, light quality and quantity of light control, energy saving, and low heat. Therefore it can be used for plant tissue culture. The application and study of LEDs had been used in plant in vitro culture. There are some previous studies of LEDs affecting growth of plant in vitro, but many questions about effects on high plants still were not understood. Spectrals light changes evoke different morphogenetic and photosynthetic responses that can vary among different plant species. Therefore, it is further to study the biological characteristics of the LED light on plantlets in vitro and dedicating light source has a significant effect on physiological, biochemical mechanisms and development of plantlets in vitro.In this study, Digitalis purpurea L. and Orychophragmus violaceus O. E. Schulz were tested to investigate the effects of light quality and light intensity on growth and development of plants, and select the feasibility of application of light quality and light intensity used in O. violaceus and D.purpurea tissue culture.Main research results were as follows:1. The effect of light spectrals on 0. violaceus plantlet in vitro was invested. The results showed that fresh weight, dry weight, stem diameter and health index of O. violaceus plantlets were superior in plants grown under R660B465G、R660B445G and R660B445Y LEDs. Biomass of O. violaceus plantlet was significantly higher under RBG or RBY LEDs than R660B465R630B445 treatment. RBG or RBY LEDs prmoted specific leaf weight of O. violaceus plantlets better than fluorescent treatments. Root activity was highest under R660B465Y LEDs. R660B465Y and R660B445Y LEDs treatments had the largest pigment content, stomata area and the least stomata number.2. The results of the effect of light spectrals on foxglove plantlets indicated that plant height, biomass, pigment content and root activity of D.purpurea plantlet in vitro under different light spectrals were significantly higher than fluorescent treatment. Fresh weight, dry weight, health index and stomata area were superior in plants grown under R630B465G and R660B465G treatments. The largest pigment content, root activity, free amino acids and net photosynthetic rate of D.purpurea were observed under R660B465G. The pigment contents of D. purpurea plantlet in vitro can be gained when green or yellow light was added to the red plus blue LEDs. Green light was more conducive to the stomatal opening and increasing of photosynthetic rate than yellow light under the combination of red and blue. R66oB465G、R660B445G and R660B445Y LEDs facilitated the growth of D.purpurea tissue culture. The combination of red and blue light increased the accumulation of sugars. Compared with fluorescent lamps, complex spectrum LEDs had obvious advantages for the culture of plants. Thus, R660B465G, R660B465G, R660B465Y and R660B445Y LEDs were suitable for the growth of D.purpurea plantlets in vitro.3. The results indicated that the effects of light intensity on growth of O. violaceus and D. purpurea plantlet in vitro were significant. The results showed that, generally speaking, the effects of light intensity on growth of O. violaceus and D.purpurea plantlet in vitro were no differences. The biomass of O. violaceus and D. purpure was largest under 50μmol·m-2·s-1. The pigments contents were significantly increased under 50μmol·m-2·s-1 to 60μmol·m-2·s-1.40pμmol·m-2·s-1 treatment induced the biggest soluble sugar in O. violaceus and D.purpure. The sucrose contents of O. violaceus and D. purpure increased firstly and then decreased as the light intensity increased. With the increasing of light intensity, the soluble contents of D. purpurea were positively correlated, while the soluble contents of O. violaceus increased firstly and decreased later. Overall, 50μmol·m-2·s-1 was the feasibility to the application of light intensity using in O. violaceus and D. purpurea tissue culture.4. The effects of complex light spectrals on growth of O. violaceus and D. purpure plantlet in vitro indicated that, stem diameter and dry weight of D.purpurea in vitro were largest under RB445G. Under RB465G treatment, fresh weight, dry weight, leaf area and pigment content of O. violaceus were largest. The highest pigment content of D.purpurea in vitro was observed under RB445W3000 treatment. There were no significant differences in light on soluble sugar content of O. violaceus and D. purpure in vitro. Our results implied that compared to other light treatments, RB465G treatment was the best light for growth of O. plantlets in vitro, while RB445G and RB445W3000 treatments were more suitable for the culture of foxglove. |
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