Analysis of the molecular composition of humic substances and their effects on physiological metabolism in maize based on untargeted metabolomics.

Introduction: Humic substances (HSs), components of plant biostimulants, are known to influence plant physiological processes, nutrient uptake and plant growth, thereby increasing crop yield. However, few studies have focused on the impact of HS on overall plant metabolism, and there is still debate over the connection between HS' structural characteristics and their stimulatory actions.

Methods: In this study, two different HSs (AHA, Aojia humic acid and SHA, Shandong humic acid) screened in a previous experiment were chosen for foliar spraying, and plant samples were collected on the tenth day after spraying (62 days after germination) to investigate the effects of different HSs on photosynthesis, dry matter accumulation, carbon and nitrogen metabolism and overall metabolism in maize leaf.

Analysis of metabolic differences in maize in different growth stages under nitrogen stress based on UPLC-QTOF-MS.

Introduction: Maize has a high demand for nitrogen during the growth period. The study of metabolic changes in maize can provide a theoretical basis for rational nitrogen nutrition regulation.

Methods: In order to investigate the changes of different metabolites and their metabolic pathways in maize leaves under nitrogen stress, we used ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) for metabolomic analysis of maize leaves under different nitrogen treatments at three critical growth stages (V4, V12 and R1) in a pot experiment under natural conditions.

Effects of fertilizer under different dripline spacings on summer maize in northern China.

Maximizing grain yields with effective fertilization technologies and minimizing nitrogen losses is essential in agroecosystems. In this research, we conducted a two-year field experiment to explore whether dripline spacing and fertilization rate would affect maize grain yield. Two dripline spacings (i.

[Hyperspectral prediction model for maize leaf SPAD in the whole growth period].

In the present article, a 2-year maize field experiment for the whole growth period was conducted. Hyperspectral data and chlorophyll contents (SPAD) of maize leaves were measured respectively using portable spectrometer and SPAD-502 chlorophyll meter. Various spectral parameters were selected to build construct prediction models for maize leaf SPAD in annual growth periods based on correlation analysis of the two factors, and detailed validation and evaluation were made.

[Spectral response of maize leaves and prediction of their nitrogen content].

In the present study, a 2-year maize field experiment with different fertilizer dose was conducted. The spectral response sensitive area of maize leaves in different levels was discussed using hyperspectral technology at booting stage. Based on the correlation analysis of original reflectivity and its first derivation with maize leaf nitrogen contents, prediction models were constructed.

[Diagnosis of nitrogen content in upper and lower corn leaves based on hyperspectral data].

Based on the spectral characters of corn leaf nitrogen content in the space, the spectral models for rapid estimating crop nitrogen content were set up, which is practically meaningful to effectively providing the guidance in fertilization. Spectral technology was applied to explore corn leaves nitrogen content distribution regularity and the relationship between the nitrogen content and plant index was analysed and then the estimation models were built. The results showed N content in upper leaves is higher than that in lower leaves in four growing stages; lower leaves at tassel emerge stage are sensitive to nitrogen losses, which could be used in guiding fertilization in grain production; optimum estimation models were built atjointing stage, the full-grown stage and tasseling stage, The research results provided the proof of crop nutrient analysis and rational fertilization.