Effect Of Light Quality On Growth,Photosynthesis And Quality In Flue-Cured Tobacco Leaves

Light quality or spectrum is the important attribute of light, at present, the ultraviolet radiation received by the earth’s surface continuously increasing owing to the air pollution and ozone concentration in air decreases, light quality has become the important factor influence the plants photosynthesis. Light quality is the principal element affecting the plant photosynthesis, morphogenesis and physiological metabolism, the study of the light qualitities’influence on photosynthetic characteristics of tobacco leaves and the materials related quality is helpful to explore new ideas and ways to improve the quality of tobacco leaves."Yunyan87" were used as the main test materials and were covered with different colored plastic films in Zunyi city, Guizhou provience (Southwest) in2010and2011. The study focused on:(1) The effect of light quality on growth, photosynthesis and quality in flue-cured tobacco leaves;(2) Effect of light quality on metabolism of carbon and nitrogen in flue-cured tobacco leaves;(3) Effect of light quality on secondary metabolism and potassium in flue-cured tobacco leaves. The main results were as follows:1. Effect of light quality on growth, photosynthesis and quality in flue-cured tobacco leavesThe study focused on the effects of light quality on growth, photosynthesis and quality in flue-cured tobacco leaves. The result showed that Blue light inhibits the growth of tobacco plant, while red light promotes the increase of leaf area; the net photosynthetic rate (Pn) of function leaves decreased lineally in2010. In2011, the Pn of function leaves, stomatal conductance (Gs) and intercellular concentration of CO2(Ci) increased after the first decrease as the film color changed from red to blue and white, so was the Stomatal conductance. By contrast, the stomatal conductance (Gs), intercellular concentration of CO2(Ci) also increased after the first decrease control under the yellow membrane while the net photosynthetic rate (Pn) and transpiration rate (Tr) continues to decline; The SPAD values of the fifth youngest expanded leaves in the2010and2011are basically the same which rised rapidly and followed with falling. The SPAD value of leaves in growth stage is higher under red and bule light and lower under yellow light. The total nitrogen, aminoacid and nicotine contents are higher under blue light, while total nitrogen and nicotine content lower under red light. The contents of chlorogenic acid and rutin are higher with blue light and the polyphenols content is lower with yellow light.2. Effect of light quality on metabolism of carbon and nitrogen in flue-cured tobacco leavesThe study focused on the effect of light quality on metabolism of carbon and nitrogen in Flue-cured tobacco leaves. The result showed that the contents of metabolism substance carbon and nitrogen are influenced by the light. The content of soluble sugar in middle and upper leaf treated with different light decreased after the first increase. Contrast with CK, covering membrane reduces the soluble sugar content in central leaves and the content of soluble sugar with red light handling is the largest. The soluble sugar content in upper leaves is largest with red light processed followed by CK and minimum with blue. The starch content in central leaves treated with different light decreased after the first increase and then raise again as the increase of leaf ages, while the upper leaves were the tendency of increase. Starch content in middle and upper leaves decreased after the cured. In middle leaves, the CK processing has the largest content while in upper leaves the value is largest with red light and smaller with yellow and bule light. The contents of amino acids and total nitrogen are decreased with the increase of leaf age. Amino acid in central leaves is biggest with the blue light and smaller with yellow while in upper leaves it is largest with blue and CK processing and small with red light. Total nitrogen in the middle leaves is largest with CK processing and followed by bule, red and yellow light while in the upper leaves it is largest with red light followed by blue and minimum with yellow before the length of leaves come to stay.3. Effect of light quality on secondary metabolism and potassium in flue-cured tobacco leavesThe study focused on the effect of light quality on secondary metabolism and potassium in flue-cured tobacco leaves. The content of chemical materials about tobacco leaves’qualitaty are influenced by the light. The chlorogenic acid content of the middle leaf treated with different light raised on whole as the increase of leaf ages. Blu light increase the chlorogenic acid content in central leaf. While the red light, yellow light, white light decreased it more obviously. The chlorogenic acid content of the upper leaf treated with different light decreased after the first increase and then raise again. It is lower than the CK, which shows that CK> Blue light> red light> yellow light> white light. The response of rutin and scopoletin on light quality are similar with the chlorogenic acid. The influence of light on the nicotine content of central and upper leaves shows that it increased overall with the age increasing, the nicotine content of the middle leaves treated with different light is Blue> Red> white> CK and yellow light, while it is most with blue light in upper leaves followed with CK and smaller with white, red and yellow. The content of potassium in upper and middle leaves decreased first and increased after baking, In middle leaves, it is higher with yellow light in the early age, red light in the medium and white in the late. After baking, it is largest with red white followed by red light and lowest with yellow light. In upper leaves, it is lager with red and yellow light before the maturity and highest with CK followed by red, white light and lowest with blue light after baking.