Lei bamboo (Phyllostachys praecox) shows greater sensitivity to salt stress than to hypoxia stress: insights from plant physiology, metabolome and soil microbiome

Abstract

Purpose

Long-term intensive management may impair nutrient uptake and physiological metabolism in Lei bamboo (Phyllostachys praecox) by altering soil oxygen levels or increasing salinity, ultimately inhibiting growth. However, the sensitivity and response mechanisms of bamboo to these two factors remain poorly understood.

Methods

A 100-day pot experiment with 8 treatment combinations was conducted, involving two soil oxygen levels (5% and 21%) and four salt concentrations (0%, 0.1%, 0.3%, 0.5%). The growth traits, root cell morphology, nutrient uptake, stress tolerance, and leaf metabolites of Lei bamboo were evaluated, along with soil physicochemical properties, enzyme activities, and bacterial community composition, to investigate soil–plant interactions.

Results

Under salt stress, Lei bamboo experienced protoplast shrinkage, root cell collapse, and a decrease in fine root numbers, hindering bamboo growth. Leaves showed curling, chlorosis, and wilting symptoms under saline conditions. Additionally, while hypoxia significantly inhibited nutrient uptake, it did not exacerbate the effects of salt stress. Antioxidant defenses, including superoxide dismutase and catalase, were activated by salt stress but diminished under hypoxia. Moreover, salt stress decreased soil pH, nitrogen, and phosphorus levels, while increasing potassium content and electrical conductivity. It altered microbial communities by reducing bacterial diversity and enzyme activities and recruiting salt-tolerant taxa like Proteobacteria, Actinobacteriota, and Acidobacteriota.

Conclusions

Lei bamboo is more sensitive to salt stress than hypoxia, with salinity identified as a critical factor driving bamboo forest decline. The negative effects of salt stress on bamboo growth, physiological traits, and soil health highlight the need for effective salinity management in bamboo forests. 

Graphical Abstract