Role of the molecular structure of humified organic matter in rice plant response to environmental lead pollution.

Humified organic matter has been shown to decrease Pb toxicity in plants. However, there are still gaps in our understanding of the mechanism by which this phenomenon occurs. In this study, we aimed to assess the ability of humic substances (HSs), humic acids (HAs), and fulvic acids (FAs) to enhance defense mechanisms in rice plants under lead (Pb)-stressed conditions.

Spectroscopic-chemometric modeling of 80 humic acids confirms the structural pattern identity of humified organic matter despite different formation environments.

The structure of humic substances (HSs) and the humification process are critical topics for understanding the dynamics of carbon on the planet. This study aimed to assess the structural patterns of 80 humic acid (HA) samples isolated from different soils, namely, Histosols, Ferralsols, Cambisols, Mollisols, Planosols and vermicompost, by spectroscopic characterization using solid-state C nuclear magnetic resonance cross-polarization/magic angle spinning combined with chemometric techniques. All 80 HAs had a similar structural pattern, regardless of their source of origin, but they had different relative quantities of organic C species.

Humic acids induce a eustress state via photosynthesis and nitrogen metabolism leading to a root growth improvement in rice plants.

Chemical eustressors induce a eustress state "positive stress" increasing the resistance and improve the plant growth. The potentiality of humic acids (HA) to act as a eustressor has been scarcely explored. The present study aims to evaluate how HA with different structural characteristics induce differently, a eustress state in rice plants through the regulation of photosynthesis.