Application Of Light Spectral Distribution Of LED On Plant Tissue Culture

The light source generally used for in vitro culture is fluorescent. However, they contain unnecessary wavelengths that are low quality for promoting growth. Compared with those traditional lamps, the improved features of the light-emitting diode(LED) include smaller mass and volume, a longer life, and a single wavelength, the light wavelength was coincidence with the spectrum that photosynthesis and morphogenesis were needed. Due to these unique characteristics, there is the suggestion that LED may be suitable for the culture of plants in a controlled environment. Light spectrum play an important role in plant development, morphogenesis, metabolism and gene expression. Application of light spectrum of LED on plantlet was important for plant tissue culture. In this thesis, Phalaenopsis and Oncidium of orchids, Ilex chinensis Sims of wooden, Dendranthema morifolium of herbaceous plantlets were tested to investigate the effects of light spectrum on growth of plantlets in different stages for plant tissue culture. The results are as follows.1.The response that light spectrum on inducing rate and differentiation rate of Phalaenopsis leaflet was unanimous. Far-red and red LED were better for induction, differentiation and proliferation from leaflet than that under fluorescence. The contents of chlorophyll, carbohydrate and enzyme activity were higher under complex light of red and blue LED than those under the fluorescent. Especially, the plantlets grew more stronger, the highest proliferation coefficient and survival rate of transplanted plantlets were observed under the light of low R/B ratio. Which could adopt as the best light in proliferation and rooting stages.2.Red LED promoted PLB induction from stem tip of oncidium obviously. Effect of proliferation and contents of carbonhydrate were greatest under red LED. A correlation was observed between proliferation effect and content of carbonhydrate. Differentiaton rate was consistent with protein content and enzyme activity, and those values were highest under blue LED. Carbohydrate content and enzyme activity in the leaves under complex of LED were higher than that of white. The results indicated that red LED is effective for PLB induction, and blue LED is advantageous for differentiation from PLB, complex of red and blue supplement with green or far-red LED are suitable for growth, rooting and transplanting success of oncidium plantlets in vitro.3.Ilex chinensis Sims under red LED exhibited the highest dry matter, rooting rate, root/shoot rate and root length, but blue LED had contrary effects. Green LED was sutitable for leave growth. However, monochromatic red LED induced abnormal growth, poor root vigor and least survival rate. Compared with fluorescent, complex of LED showed the obvious advantages on energy efficiency, pigment content, dry weight, SOD and CAT activities. The results indicated that application of complex of LED can improve the photosynthetic and antioxidant capacity of Ilex chinensis Sims plantlets in vitro.4.Chrysanthemum under monochromatic red or blue LED induced abnormal growth, poor root vigor and least survival rate. Comparing with fluorescent, complex of red and blue LED showed the obvious advantages on C/N ratio, SOD and POD activities. In conclusion, RB、RBG or RBFr LED were suitable for growth of chrysanthemum in vitro.5.The ratios of light spectrum had significance effects on growth of plantlets. Red LED promoted the growth of chrysanthemum plantlets and increased root length, contrary to far-red LED and blue LED. Carotenoid content was negatively related to R/Fr ratio. The contents of chlorophyll and carotenoid were also negatively related to R/B ratio. Chlorophylla/b ratio were correlated with R/B and R/Fr ratio positively. Contents of soluble sugar, starch in leaves and root activity were higher under the complex of red and blue LED than those under fluorescent. the plantlets grew more stronger and the highest survival rate of transplanted plantlets were observed under the light of high R/B ratio.In conclude, the sensitivity of plantlets breed and growth stages showed diversity to light spectrum. The common as well as difference of plantlets manifested under different light spectrum of LED: plantlets under red showed excessive growth, content of chlorophyll was lower, but chla/b was high, red light promoted accumulation of starch in leaf. however, those effects were reversed by blue, plantlet and root length were small, but content of soluble protein and amino acid, root activity were highest, Plantlets under the complex of red and blue supplement with green or far-red LED was stronger, physiological and biochemical characteristics were better than fluorescence. This study supported the feasibility of application of light spectrum regulation of LED on growth of plantlets in vitro, which would replace fluorescent and be widely used in plant tissue culture.