Figure 1.

Effects of different nitrogen ion forms and water stress on SOD (a), POD (b), PPO (c) and MDA (d). Treatments: CK, seedlings treated normal water and basic nutrient without nitrogen; N, seedlings treated with NO₃⁻N only; A, seedlings treated with NO₄⁺-N only; AN, seedlings treated with NO₃⁻N and NO₄⁺-N in combination; P, seedlings with 10% PEG; NP, seedlings with NO₃⁻N + 10% PEG; AP, seedlings with NO₄⁺-N + 10% PEG; ANP, seedlings treated with NO₃⁻N and NO₄⁺-N in combination +10% PEG. Mean (± SD) was calculated for three replicates for each treatment. Vertical bars with different lowercase letters are significant at P < 0.05, determined by LSD test.