Figure 3.

Effects of different nitrogen ion forms and water stress on NR activity (a) and GS activity (b) and GOGAT activity (c). Treatments: CK, seedlings treated with 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 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.