Mechanism of paraquat tolerance in cucumber leaves of various ages

Yong In Kuk, Ji San Shin, Ha Il Jung, Ja Ock Guh, Sunyo Jung, Nilda R. Burgos

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Differential sensitivity to paraquat was observed between cucumber cultivars and leaf age. Physiological responses to paraquat, including antioxidative enzyme activity, were investigated in leaf age classes of cucumber to identify mechanisms of paraquat tolerance. Leaf injury for 'Naeseosamcheok', 'Daehandadagi', 'Baekgwangdadagi', 'Sangrokheukjinju', and 'Eunseongbaekdadagi' cultivars was less than that of six other cultivars tested, averaged over leaf age and herbicide rate. The level of foliar injury caused by paraquat was Leaf 1 > 2 > 3 > 4 in seven of 11 cultivars used, where 4 was the youngest leaf. There was a positive correlation between leaf age and its relative susceptibility to paraquat, regardless of growth stage. Lipid peroxidation was less in the youngest leaf (Leaf 4) than in the older leaves at all herbicide concentrations. The youngest leaf had higher values for apparent photosynthesis than the oldest leaf. Differential leaf response to paraquat was partially correlated with the change in superoxide dismutase, ascorbate peroxidant, and glutathione reductase activities in treated leaves. Enzyme activity of ascorbate peroxidase (APX) was higher in Leaf 4 than in Leaves 1, 2, or 3 in untreated plants and after exposure to paraquat. APX isozymes were more abundant in treated than in untreated leaves and produced in higher amounts in younger than in older leaves. Application of ascorbate and glutathione before paraquat treatment protected cucumber leaves from paraquat injury.

Original languageEnglish
Pages (from-to)6-15
Number of pages10
JournalWeed Science
Issue number1
StatePublished - 2006


  • Antioxidative enzyme
  • Lipid peroxidation
  • Photosynthesis


Dive into the research topics of 'Mechanism of paraquat tolerance in cucumber leaves of various ages'. Together they form a unique fingerprint.

Cite this