不同光质LED光源对黄瓜幼苗光合参数、水分利用效率和叶绿体超微结构的影响

Effects of Different LED Light Qualities on the Photosynthetic Parameters,Water Utilization Efficiency and Chloroplast Ultrastructure of Cucumber Seedling

采用发光二极管(LED)为光源,以白光作对照,研究了红光、蓝光和红蓝组合光对黄瓜品种"银胚99"幼苗叶片光合参数及水分利用效率的影响,并观察了叶绿体超微结构的变化。结果表明,蓝光和红蓝组合光均显著提高了叶片的净光合作用,在处理到第10天时,蓝光提高幅度最大,较白光高出27.29%;在处理到第20天时,红蓝组合光8R/2B提高叶片光合速率幅度最大,较白光高出56.94%。红蓝组合光处理下叶片的后期净光合速率下降较小,水分利用效率提高显著。与白光相比,红光处理对叶片净光合速率的影响不存在差异,且在处理第20天时叶片净光合速率和水分利用效率与第10天相比,有明显下降。叶片叶绿体超微结构显示,不同光质对黄瓜幼苗叶绿体发育有显著影响;白光不利于叶片叶绿体的成熟,红光造成叶片叶绿体淀粉粒过分积累,抑制了光合产物从叶片中的输出;红蓝组合光8R/2B和7R/3B处理则有利于叶绿体基质、基粒片层的形成和同化产物的输出。

By using LED modulated light qualities accurately, We observed the effects of red, blue, red and blue mixed light generated by LED on the photosynthetic parameters and water utilization efficiency as well as chloroplast ultrastructure of cucumber seedlings with white ligh as control. It showed that the different light qualities had significant influence on the plant photosynthetic parameters, the growth and development of cucumber seedlings. The net photosynthetic rates under the circumstances of blue light and red＋ blue mixed light were generally higher than those in other treatments. Net photosynthetic rate under blue light was obviously the highest in value at the 10th day among all treatments, which was 27.29% higher than with that in white light, and the highest net photosynthetic rate at the 20th day was obtained in 8R/2B treatment, which was 56.94% higher than in white light. Furthermore, it showed that red and blue mixed light sources seem to keep photosynthetic rates at very high level at both 10th and 20th day, and to promote water utilization efficiency significantly. However, the red light effect on photosynthetic rates were not significant different at 0.05 level even if photosynthetic rates and water utilization efficiency at the 20th day decreased remarkably compared with the 10th day. It was observed by transmission electronic microscope that light qualities had remarkable influences on the chloroplast development of cucumber seedlings. The chloroplast under the white light seemed to be difficult to maturate, while red light was probable to hinder the photosynthates transport by the over-accumulation of starch in the chloroplast. Both grana lamella and stroma lamella of chloroplast appeared to well-developed under the 8R/2B and 7R/3B treatments, and the assimilation products were also well-exported in these two treatments.