3.2 │ Peroxidase activity (POX)
Analysis of variance and changes in POX activity in the roots of the six cucumber genotypes with different levels of resistance after inoculation with P. melonis was represented in Table 2 and 3 and Fig 2. In Ramezz and Baby, POX activity indicated a significant increase in 14 DAI, and increased to maximum at 21 DAI (Fig 2.B and C). Highest POX activity of 80.8 units was recorded in resistant Ramezz after 21 DAI which was 6 folds higher than that of the untreated control which recorded 13.8 units POX activity after 21 DAI (Fig 2.C). Soheil increased at 7 and 14 DAI had a decrease of SOD activity at 28 DAI and showed no significant difference between control and inoculated at 28 DAI. (Fig 2.A). Pattern study of POX activity in inoculated susceptible samples of Mini 6-23 and Extrem were similar to the uninoculated samples, but, the amount of enzyme activity was significantly higher in inoculated susceptible samples of Yalda at 21 DAI. Interestingly, the POX activity in infected plants of Extrem was lower than controls (Fig 2.D). The increase in POX activity caused by inoculation varied among genotype and has a strong negative correlation with damping-off susceptibility at 14 DAI (Supplemental Table 1).