Response Strategies of Root System Architecture to Soil Environment: A Case Study of Single-Species Cupressus funebris Plantations

Wenchun He; Chao Luo; Yang Wang; Xiaochen Wen; Yu Wang; Tianyi Li; Gang Chen; Kuangji Zhao; Xianwei Li; Chuan Fan

doi:10.3389/fpls.2022.822223

Response Strategies of Root System Architecture to Soil Environment: A Case Study of Single-Species Cupressus funebris Plantations

Front Plant Sci. 2022 Apr 14:13:822223. doi: 10.3389/fpls.2022.822223. eCollection 2022.

Authors

Wenchun He¹, Chao Luo¹, Yang Wang¹, Xiaochen Wen¹, Yu Wang¹, Tianyi Li¹, Gang Chen¹, Kuangji Zhao¹, Xianwei Li¹, Chuan Fan¹

Affiliation

¹ College of Forestry, Sichuan Agricultural University, Sichuan Province Key Laboratory of Ecological Forestry Engineering on the Upper Reaches of the Yangtze River, State Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River, Chengdu, China.

Abstract

The root system architecture (RSA), being a key characteristic of the root economic spectrum, describes the spatial arrangement and positioning of roots that determines the plant's exploration of water and nutrients in the soil. Still, it remains poorly understood how the RSA of woody plants responds to the demand for water and nutrients in different soil environments and how the uptake of these resources is optimized. Here we selected single-species plantations of Cupressus funebris and determined their topological index (TI), revised topological index (q _a and q _b ), root link length (RLL), root branching rate (R _b and R _i :R _{_i+1}), and in situ soil physicochemical properties to assess which root foraging strategies adopt in different soil environments among Guang'an City (GA), Suining City (SN), Mianyang City (MY), and Deyang City (DY) in China. We also tested the potential effects of different nutrients upon RSA according to its plastic phenotype. Principal component analysis (PCA) showed that levels of soil nutrients were the highest at DY, followed by MY and SN, and lower at GA. A dichotomous branching pattern was observed for GA, SN, and MY, but a herringbone branching pattern for DY. The RLL was ranked as GA, > SN, > MY > DY. The R _b of GA, SN, and MY was significantly lower than that of DY (p < 0.05). Among the different city regions, values of R ₁ /R ₂ were the largest in different regions and those of R ₄ /R ₅ the smallest. The cross-sectional area of the root system did not differ between any two connected branch orders. The TI, q _a , and RLL were significantly and negatively correlated with soil's water content, porosity, total nitrogen, total potassium, available nitrogen, and available phosphorus (p < 0.05), whereas they all had significant, positive relationships with soil temperature (p < 0.05). The R _b was significantly and positively correlated with total potassium in soil (p < 0.05). Redundancy analysis showed that total potassium was the main factor driving variation in RSA. Our results emphasize that the RSA is capable of corresponding plastic alterations by changing its number of internal or external links and the root link length of fine roots vis-à-vis a heterogeneous environment, thereby optimizing the rates of water capture and space utilization.

Keywords: Cupressus funebris; fine root; response strategy; root system architecture; soil environment.