Work

Effects of Simulated Water Depth and Nitrogen Addition on Phragmites australis Root Anatomy

Year: 2026

Type: article

Abstract: Root anatomy serves as a critical indicator for understanding wetland plant adaptation strategies to environmental changes. Since water depth determines root oxygen demand while nitrogen addition regulates nutrient acquisition, the two factors exert significant and interactive effects on root anatomical structure. In this study, we established a controlled experiment employing three water depth treatments (W1: −10 cm; W2: 10 cm; W3: 30 cm), two nitrogen (N) forms (ammonium-N, nitrate-N), and four N addition levels (N0: 0 mg/L; N1: 40 mg/L; N2: 80 mg/L; N3: 160 mg/L). This design enabled us to analyze the effects of water–nitrogen interactions on the anatomical structure of reed roots to reveal wetland plants’ adaptive strategies to water-nitrogen fluctuations. The results indicate that (1) under nitrogen-free treatment, compared to the control group, the W1 treatment reduced the root aerenchyma proportion and the stele-to-root diameter ratio by 15.8% and 37.0%, respectively. In contrast, exodermis thickness increased by 32.4%, while epidermis thickness decreased by 33.7%. Under the W3 treatment, the aerenchyma proportion increased by 21.0%, the stele-to-root diameter ratio decreased by 22.2%, and exodermis thickness increased by 35.3%. (2) Compared to the nitrogen-free treatment, nitrate addition increased the root aerenchyma proportion under W1, W2, and W3 by 18.8%, 6.9%, and 18.3%. The stele-to-root diameter ratio increased by 27.9% and 12.7% under W1 and W2, but decreased by 10.8% under W3. Exodermis thickness increased by 26.3% under W2, whereas it decreased by 10.8% under W3. Epidermis thickness increased by 36.1% and 22.2% under W1 and W3, while a decrease of 12.7% occurred under W2. (3) Compared to the nitrogen-free treatment, ammonium addition increased the root aerenchyma proportion under W1, W2, and W3 by 13.6%, 13.2%, and 10.0%. The stele-to-root diameter ratio increased by 28.1% under W1 but decreased by 10.4% under W3. Conversely, exodermis thickness decreased by 20.2% under W1 while increasing by 12.6% under W3. Epidermis thickness increased by 26.3% and 20.8% under the W1 and W3 treatments. In summary, the root anatomical structure of P. australis adaptively responds to variations in water depth, nitrogen forms, and nitrogen concentrations by modulating aerenchyma proportion, the stele-to-root diameter ratio, exodermis thickness, and epidermis thickness. Future research should strengthen the study of the relationship between root anatomical traits and plant functions, to more comprehensively explore the adaptation mechanisms of wetland plants to global environmental change.

Source: Water

DOI: 10.3390/w18020243

Authors: Mingyu Zhang, Changwei Zhang, Guijun Wang, Zhenwen Xu, Yanjing Lou

Institutions: Changchun Normal University, Chinese Academy of Sciences, Northeast Institute of Geography and Agroecology

Language: English

Topic: Plant responses to water stress

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

Open Access status: gold

Estimated APC paid: $3,137

Funders: National Natural Science Foundation of China, Changchun Normal University