The change in the activities of PPO (µmol ⁻¹ mg _prot ⁻¹   min⁻¹) in the root (A), leaf (B) and rhizome (C) of P. communis at investigated sites Necik and Sinjak of Bardaca wetland. The values are expressed as mean of three repetition ± SE. Different small letters indicate statistical significance between months within the same site (a, b, c, d, e for Necik and a₁, b₁, c₁, d₁, e₁, for Sinjak) according to LSD test (p < 0.05).