Variations in root architecture and morphology of two wheat genotypes with contrasting phosphorus efficiency

L Nguyen and J Stangoulis

School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001

Root system architecture (RSA) and morphology are important for improvements of phosphorus (P) efficiency, however wheat has a sparse crown root system that is not easy to obtain without destruction for RSA analysis. In this study, a simple soil-based cultivation was developed to obtain a wheat root system without destruction for two-dimensional (2-D) RSA analysis. Two wheat genotypes RAC875 and Wyalkatchem with contrasting P efficiency were used for the studies. RAC875 produced greater grain yield than Wyalkatchem under low P but no significant difference was observed under adequate P. In contrast, RAC875 had a smaller root dry matter than Wyalkatchem at maturity. RSA traits were measured at 24 days after sowing (DAS) using Gia Roots and DIRT and root hair features were also estimated at 7 DAS to identify which root traits may be correlated to P efficiency in RAC875. P supply affected most RSA traits where P deficiency reduced the root convex hull area (CHA), root surface area, root volume, total root length, root tip number, spatial root distribution (Y). Under low P supply, RAC875 produced greater CHA than Wyalkatchem, while Wyalkatchem had significantly larger CHA than RAC875 under adequate P. Under low P, shoot dry matter was positively correlated to CHA. Wyalkatchem produced longer root hairs than RAC875. However, RAC875 had denser root hairs than Wyalkatchem under low P but no significant differences occurred at adequate P. Larger CHA and denser root hairs appears to support a greater biomass and yield production in RAC875 under P deficiency. Thus, convex hull area and root hair density are potential indicators when screening for P efficient wheat.