Background Low phosphorus (P) use efficiency represents a major constraint in pepper production. Meanwhile, γ-polyglutamic acid (γ-PGA) has been reported to improve nutrient retention and stimulate plant growth. This study evaluated the effects of combined P fertilizer and γ-PGA application on pepper growth, nutrient uptake, yield, and phosphorus use efficiency in pepper plants during entire plant development period. Methods A two-factor pot experiment was conducted with three P levels (0, 2.0, 4.0 g plant⁻1) and two γ-PGA concentrations (0, 450 mg L⁻1). Morphological traits, root architecture, physiological parameters, nutrient uptake, yield, and P use efficiency (PUE) were determined. Data were analyzed using two-way ANOVA, principal component analysis (PCA), and structural equation modeling (SEM). Results The results showed that P application alone significantly increased pepper growth, leaf and root traits, total biomass and fruit yield (p < 0.05). Soluble protein, proline, SOD and POD activities were elevated with increasing P supply (p < 0.05), while MDA content was reduced (p < 0.05). P combined with γ-PGA further enhanced plant height, stem diameter, chlorophyll content, biomass and yield (p < 0.05); notably, root surface area increased substantially (p < 0.01). Macronutrient and micronutrient concentrations and accumulations were also significantly improved under combined treatments (p < 0.05). P + γ-PGA further promoted SOD and POD activities (p < 0.05) but weakened CAT activity (p < 0.05), implying distinct ROS quenching pathways. γ-PGA also significantly improved phosphorus use efficiency (p < 0.05). SEM revealed contrasting regulatory pathways: the antioxidant system negatively regulated fruit nutrients via growth traits without γ-PGA, while P + γ-PGA directly enhanced fruit yield (p < 0.05) and indirectly improved fruit nutrients by promoting growth traits (p < 0.05). Moderate P combined with γ-PGA was confirmed as the optimal treatment for pepper growth and yield (p < 0.05). Conclusions The combined application of moderate P (2.0 g plant⁻1) and γ-PGA (450 mg L⁻1) is the optimal strategy to improve pepper growth, root morphology, nutrient uptake, antioxidant status, fruit yield, and PUE. This strategy provides a practical approach for reducing phosphorus fertilizer input and supporting sustainable pepper production.

Synergistic phosphorus fertilization with γ-polyglutamic acid enhances pepper yield via improved root development and nutrient uptake

期刊论文
出版模式：

开放获取
发表日期：

2026年4月30日

查看全文

Xinglian Li,
Zhenzhu Xu,
Jianjian Wang

摘要

Background

Low phosphorus (P) use efficiency represents a major constraint in pepper production. Meanwhile, γ-polyglutamic acid (γ-PGA) has been reported to improve nutrient retention and stimulate plant growth. This study evaluated the effects of combined P fertilizer and γ-PGA application on pepper growth, nutrient uptake, yield, and phosphorus use efficiency in pepper plants during entire plant development period.

Methods

A two-factor pot experiment was conducted with three P levels (0, 2.0, 4.0 g plant⁻¹) and two γ-PGA concentrations (0, 450 mg L⁻¹). Morphological traits, root architecture, physiological parameters, nutrient uptake, yield, and P use efficiency (PUE) were determined. Data were analyzed using two-way ANOVA, principal component analysis (PCA), and structural equation modeling (SEM).

Results

The results showed that P application alone significantly increased pepper growth, leaf and root traits, total biomass and fruit yield (p < 0.05). Soluble protein, proline, SOD and POD activities were elevated with increasing P supply (p < 0.05), while MDA content was reduced (p < 0.05). P combined with γ-PGA further enhanced plant height, stem diameter, chlorophyll content, biomass and yield (p < 0.05); notably, root surface area increased substantially (p < 0.01). Macronutrient and micronutrient concentrations and accumulations were also significantly improved under combined treatments (p < 0.05). P + γ-PGA further promoted SOD and POD activities (p < 0.05) but weakened CAT activity (p < 0.05), implying distinct ROS quenching pathways. γ-PGA also significantly improved phosphorus use efficiency (p < 0.05). SEM revealed contrasting regulatory pathways: the antioxidant system negatively regulated fruit nutrients via growth traits without γ-PGA, while P + γ-PGA directly enhanced fruit yield (p < 0.05) and indirectly improved fruit nutrients by promoting growth traits (p < 0.05). Moderate P combined with γ-PGA was confirmed as the optimal treatment for pepper growth and yield (p < 0.05).

Conclusions

The combined application of moderate P (2.0 g plant⁻¹) and γ-PGA (450 mg L⁻¹) is the optimal strategy to improve pepper growth, root morphology, nutrient uptake, antioxidant status, fruit yield, and PUE. This strategy provides a practical approach for reducing phosphorus fertilizer input and supporting sustainable pepper production.