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Effects of silicon on photosynthetic characteristics and activity of antioxidant enzymes in continuous-cropped cucumber seedlings.

ZHANG Ping-yan1, GAO Rong-guang1, YANG Feng-juan1,2,3, WANG Xiu-feng1,2,3, WEI Min1,2, SHI Qing-hua1,2, LI Yan1,2   

  1. (1College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271018, Shandong, China; 2State Key Laboratory of Crop Biology, Tai’an 271018, Shandong, China; 3Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Huanghuai Region), Ministry of Agriculture, Tai’an 271018, Shandong, China)
  • Online:2014-06-18 Published:2014-06-18

Abstract: The effects of spraying exogenous silicon (Si) (0, 1, 2, 3, 4 and 5 mmol·L-1) on the growth, photosynthetic characteristics and activity of antioxidant enzymes in continuouscropped ‘Jinyan NO.4’ cucumber seedlings were studied. The results showed that with the application of 1-3 mmol·L-1 Si, electrolyte leakage (EL) and malondialdehyde (MDA) content in leaves were significantly decreased, while the contents of chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoids (Car), chlorophyll (a+b) and photosynthetic rate (Pn) in leaves were significantly improved, the activities of superoxidase (SOD), peroxidase (POD), catalase (CAT) and ascorbic acid peroxidase (APX) were significantly increased, and the plant height, stem diameter and dry mass accumulation of cucumber seedlings were promoted. Compared with the low Si concentrations, excessive Si (4-5 mmol·L-1) resulted in higher EL and MDA, which were still lower than that in control, decreased the antioxidant enzymes activity and photosynthesis, and inhibited the growth of cucumber seedlings.  These findings indicated that exogenous Si could enhance the capacity of scavenging active oxygen species and improve photosynthesis, protect cucumber seedlings from the lipid peroxidation, and increase the resistance to continuouscropped cucumber obstacle.
 The optimal silicon concentration was 2 mmol·L-1.