2.3. Trait measurements and calculations
After washing the impurities on the surface of the collected root
systems with distilled water, the relevant parameters were measured. The
roots of each plant were scanned using the Epson Perfection V850 Pro
Scanner (Epson, Los Alamitos, CA USA), then the scanned root images were
numbered and stored in a computer. Each image was analyzed using the
root analysis system software Win-RHIZO Pro 2013 (Regent Instruments
Inc., Canada) to measure total root length (TRL), root surface area
(RSA), root diameter (RD), and root volume (RV). After scanning, the
root system and the aboveground part were put into different empty
envelopes respectively, and dried them to constant weight in an 80 ℃
oven. The dry weight of each part was weighed with the electronic
balance (0.1mg). The specific root length (SRL) was calculated as the
ratio of total root length to biomass, the root mass fraction (RMF) was
root biomass to individual plant biomass, the specific root area (SRA)
was surface area to biomass, and the root tissue density (RTD) was
biomass to root volume.