# Chlorophyll fluorescence characteristics and H2O2 contents of Chinese tallow tree are dependent on population origin, nutrients and salinity

## TL;DR

This study shows how Chinese tallow tree populations from the USA and China differ in their photosynthetic and antioxidant responses to nutrients and salt.

## Contribution

The paper reveals how population origin, nutrients, and salinity affect chlorophyll fluorescence and H2O2 in an invasive plant.

## Key findings

- Introduced population plants were larger but less resilient under saline or low-nutrient conditions.
- Native plants had lower Fv/Fm under salinity, while introduced plants had lower electron transfer rates in high-nutrient conditions.
- Hydrogen peroxide levels were lower in introduced populations, but increased with salinity and nutrient stress.

## Abstract

Plants from invasive populations often have higher growth rates than conspecifics from native populations due to better environmental adaptability. However, the roles of improved chlorophyll fluorescence or antioxidant defenses in helping them to grow better under adverse situations are insufficient, even though this is a key physiological question for elucidating mechanisms of plant invasion. Here, we conducted experiments with eight native (China) and eight introduced (USA) populations of Chinese tallow tree (Triadica sebifera). We tested how salinity, nutrients (overall amount or N:P in two separate experiments) and their interaction affected T. sebifera aboveground biomass, leaf area, chlorophyll fluorescence and antioxidant defenses. Plants from introduced populations were larger than those from native populations, but salinity and nutrient shortage (low nutrients or high N:P) reduced this advantage, possibly reflecting differences in chlorophyll fluorescence based on their higher PSII maximum photochemical efficiency (Fv/Fm) and PSI maximum photo-oxidizable P700 in higher nutrient conditions. Native population plants had lower Fv/Fm with saline. Except in high nutrients/N:P with salinity, introduced population plants had lower electron transfer rate and photochemical quantum yield. There were no differences in antioxidant defenses between introduced and native populations except accumulation of hydrogen peroxide (H2O2), which was lower for introduced populations. Low nutrients and higher N:P or salinity increased total antioxidant capacity and H2O2. Our results indicate that nutrients and salinity induce differences in H2O2 contents and chlorophyll fluorescence characteristics between introduced and native populations of an invasive plant, illuminating adaptive mechanisms using photosynthetic physiological descriptors in order to predict invasions.