The effects of different light qualities on the photosynthesis efficiency, carbohydrate metabolism and antioxidant capacity of the sweet potato seedings

• Main Authors: Kuo-Yin Lin, 林國英
• Other Authors: Yu-Chie Wang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/96817995400529958978

碩士 === 國立臺灣師範大學 === 生命科學研究所 === 99 === The leaf of sweet potato (Ipomoea batatas (L.) Lam.) is an important antioxidant vegetable. The light emitting diode (LED) is a promising artificial light source because of its small mass and volume, and can provide specific light quality, light quantity, light frequency and duty ratio. This paper uses the LED as an artificial light source to provide blue light (470 nm) and red light (660 nm) for sweet potato seedings, and discusses the antioxidant capacity, photosynthesis efficiency, and carbohydrate metabilism of the sweet potato seedings cultivated under different light qualities. The data of chlorophyll fluorescence showed that photosystemⅡof the sweet potato seedings cultivated under blue, red or full-light for 5 days was not destroyed. NPQ of the sweet potato leaves cultivated under red light was significantly lower than that under blue or full-light. According to the previous research data, we can suggest that the leaves of sweet potato under red light might reduce the biosynthesis of zeaxanthin. The reduced glutathion (GSH) content, oxidized glutathion (GSSG) content, ascorbate peroxidase (APX) activity and superoxide dismutase (SOD) activity of the sweet potato leaves cultivated under blue, red or full-light for 5 days didn’t show the significant difference, but catalase (CAT) content of the sweet potato leaves cultivated under blue light was higher, and H2O2 content of the sweet potato leaves cultivated under blue or red-light was lower than that under full light. We can presume that the reactive oxygen species content of the sweet potato leaves cultivated under blue light reduced by CAT. The results of the contents of carbohydrates and the activities of the enzymes to participate in carbohydrate metabilism showed the different light qualities didn’t affect starch content of the sweet potato leaves, but glucose, fructose and sucrose contents of the sweet potato leaves cultivated under blue light were remarkably higher than those under red light. We can speculate that the activities of sucrose phosphate synthase (SPS) and invertase (INV) of the sweet potato leaves cultivated under blue light were higher than those under red light was the reason for foregoing results. Furthermore, the sweet potato leaves cultivated under full light had higher activities of acid INV and alkaline INV, and those under red light had lower activities of acid INV and alkaline INV than those under blue light. The activites of SPS and INV of the sweet potato leaves cultivated under blue, red, or full-light had significant difference, but the expressions of gene of SPS, sucrose synthase (Susy) , and INV displayed by Real-time PCR were not different. Therefore, the activity of SPS and INV might be affected by post-translation. Although the densities of the stroma of the sweet potato leaves cultivated under blue, red, or full-light didn’t have significant difference, the ratio of the open stroma of the sweet potato leaves cultivated under blue light was the highest. As a whole, the sweet potato seedings cultivated under blue light were growing abundantly, and the leaves of those had higher antioxidant capacity, more glucose, more fructose, more sucrose, and higher ratio of the open stroma. Those results indicate that blue light is better than red or full-light for sweet potato seedings.