Effects of nitrogen and magnesium nutrient on the plant growth, quality, photosynthetic characteristics, antioxidant metabolism, and endogenous hormone of Chinese kale (Brassica albograbra Bailey)

In this study, the variety Cuibao' was used as material. Hydroponic culture trial was conducted to investigate the effects of nitrogen (N) and magnesium (Mg) on plant growth, quality, photosynthetic characteristics, antioxidant metabolism, and endogenous hormone of Chinese kale. Three N levels (2.5, 7.5 and 22.5 mmol/L) and three Mg levels (0.5, 1.4 and 4.2 mmol/L) were applied, respectively. The experiment was laid out in a completely orthogonal design which formed a total of nine different combined treatments of N and Mg (N2.5Mg0.5, N2.5Mg1.4, N2.5Mg4.2, N7.5Mg0.5, N7.5Mg1.4, N7.5Mg4.2, N22.5Mg0.5, N22.5Mg1.4, and N22.5Mg4.2). As compared to other combined treatments, the N7.5Mg1.4 treatment obviously promoted plant weight and improved the quality. Moreover, the N7.5Mg1.4 treatment significantly increased catalase (CAT) activity and decreased the contents of malondialdehyde (MDA) and proline (Pro). Interestingly, the combinations of N and Mg significantly affected the homeostasis of endogenous hormones. The N7.5Mg1.4 treatment obviously increased the contents of growth promoting hormones indo-3-acetic acid (IAA) and zeatin (ZT) and reduced the contents of growth inhibitory hormone abscisic acid (ABA), increased the ratios of IAA/ABA, gibberellin acid (GA(3))/ABA and ZT/ABA. These results revealed that the reasonable combined treatment of N and Mg effectively improved the photosynthetic characteristics, and the homeostasis of antioxidant metabolism and endogenous hormones, which resulted in regulating the plant growth and increasing plant fresh weight of Chinese kale.

Automated summary

This study investigated the effects of nitrogen (N) and magnesium (Mg) on the growth, quality, photosynthetic characteristics, antioxidant metabolism, and endogenous hormones of Chinese kale. The results showed that a reasonable combination of N and Mg significantly improved the growth and quality of Chinese kale, as well as regulated the balance of antioxidant metabolism and endogenous hormones.