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  Eur.J.Hortic.Sci. 80 (2) 76-80 | DOI: 10.17660/eJHS.2015/80.2.5
ISSN 1611-4426 print and 1611-4434 online | © ISHS 2015 | European Journal of Horticultural Science | Original article

Antioxidant compounds and activity in cucumber fruit in response to foliar and soil humic acid application

Y. Karakurt1, H. Ozdamar-Unlu2, H. Unlu2 and M. Tonguc1
1 Suleyman Demirel University, Faculty of Agriculture, Agricultural Biotechnology Department, 32260, Isparta, Turkey
2 Suleyman Demirel University, Faculty of Agriculture, Horticultural Sciences Department, 32260, Isparta, Turkey

Humic acid (HA), with its hormon-like activity influences yield and quality of fruits and vegetables. This study was performed to determine the influence of foliar and soil HA fertilization on antioxidant properties of cucumber fruit. Cucumber plants were treated with soil and foliar HA at various concentrations (0 mL L-1, 10 mL L-1, 20 mL L-1, 30 mL L-1 a nd 4 0 m L L -1) via spraying or drenching to the plant root area. Fruits were harvested at commercial maturity and their antioxidant activities in the hydrophilic (HAA) and lipophilic (LAA) fractions, lycopene, beta carotene, xanthophylls, total phenolics and chlorogenic acid contents were determined. The results demonstrated that HA application significantly improved both HAA and LAA activities in cucumber fruit. Moreover, HA also significantly enhanced total carotenes and xanthophylls, beta carotene, lycopene and chlorogenic acid contents. The data suggested that HA could be used to significantly improve cucumber fruit quality by enhancing its content of antioxidant compounds.

Keywords antioxidants, carotenoids, fruit, humic acid, phenolics, quality

Significance of this study

What is already known on this subject?

  • Humic acid with its hormon-like activity improves the yield and quality of fruits and vegetables. Cucumber fruit has a very low level of antioxidants, and it is not known if humic acid can improve the antioxidant content of cucumber fruit.
What are the new findings?
  • The application of humic acid improves cucumber fruit quality by enhancing its content of antioxidant compounds.
What is the expected impact on horticulture?
  • Cucumber fruit with high contents of antioxidant compounds offer great economic and health benefits.

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Received: 20 March 2014 | Revised: 9 January 2015 | Accepted: 3 March 2015 | Published: 22 April 2015 | Available online: 22 April 2015

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