On Sept 16th in 2020 and 2021, ten maize plants were selected from each replicate of fertilizer application treatments to measure plant growth indexes of maize, including plant height (cm), stem diameter (cm), root weight (g) and plant weight (g). The foliar contents of nutrients were determined, including soluble sugars (mg/g), soluble protein (mg/g) and free fatty acids (FFA; mg/g), and the correspondingly used kits were No.A145-1-1, No.A145-1-1 and No.A042-1-1 respectively, which were provided by Nanjing Jiancheng Bioengineering Institute at Nanjing City, Jiangsu Province of China.
On the other hand, the activity of three nitrogen metabolic enzymes [including NADH-GOGAT (nmol/min/g), NR (mmol/h/g), GS (mmol/h/g)] in maize leaves was also determined by using the correspondingly used kits of No BC0075, No BC0080 and No BC0915 respectively, which were provided by Beijing Suolaibao Technology Co. Ltd. at Beijing City of China. And the foliar contents of secondary metabolites, including total phenol (mg/g), tannin (mg/g) and flavonoids (ng/g) were measured by using the colorimetric methods with catechol, gallic acid and rutin as the standard curves (Ali et al., 2022) (link); the hormone contents of JA (pmol/g), SA (pmol/g) and JA-Ile (pmol/g) were further assays were done by using the HPLC-MS/MS (LCMS-8040 system, Shimadzu), referred to Wu et al. (2007) (link).
On the other hand, the activity of three nitrogen metabolic enzymes [including NADH-GOGAT (nmol/min/g), NR (mmol/h/g), GS (mmol/h/g)] in maize leaves was also determined by using the correspondingly used kits of No BC0075, No BC0080 and No BC0915 respectively, which were provided by Beijing Suolaibao Technology Co. Ltd. at Beijing City of China. And the foliar contents of secondary metabolites, including total phenol (mg/g), tannin (mg/g) and flavonoids (ng/g) were measured by using the colorimetric methods with catechol, gallic acid and rutin as the standard curves (Ali et al., 2022) (link); the hormone contents of JA (pmol/g), SA (pmol/g) and JA-Ile (pmol/g) were further assays were done by using the HPLC-MS/MS (LCMS-8040 system, Shimadzu), referred to Wu et al. (2007) (link).