Variation in root system architecture and morphology of two wheat genotypes is a predictor of their tolerance to phosphorus deficiency

Van Lam Nguyen,James Stangoulis

doi:10.1007/s11738-019-2891-0

Abstract

Variation in root system architecture (RSA) and morphology are important for improving phosphorus use efficiency (PUE) in wheat. This work aims to analyze the root system architecture and morphology of wheat genotypes to explain their variation in PUE. Two genotypes differing in PUE, RAC875 (P efficient) and Wyalkatchem (P inefficient) were grown in a sandy soil amended with adequate basal nutrients and two P rates (10 and 30 mg P kg−1). RSA traits were measured by freely available software, GiA roots and DIRT, and root hair features were measured using a microscope with an attached camera and LAS v3.6 software. Under low P supply, RAC875 produced greater shoot dry matter (DM) at 24, 27 and 48 days after sowing (DAS), and at maturity, RAC875 also had a higher grain yield at maturity. Enhanced P efficiency (biomass and seed yield at inadequate P supply relative to adequate P supply) was observed more so in RAC875 at all harvest times. P supply affected most RSA traits, with low P leading to reductions in convex hull area (CHA), root surface area, root volume, total root length and root tip number. RAC875 produced significantly greater CHA than Wyalkatchem at low P supply while Wyalkatchem had significantly larger CHA than RAC875 when P was non-limiting. RAC875 also had greater root hair density (RHD) than Wyalkatchem at low P level, but no difference was observed at adequate P. When grown under low P supply, a greater CHA and RHD in RAC875 were likely to contribute to improved P uptake, resulting in its higher shoot biomass and grain yield.

Highlights

As roots are the conduit for mineral and water acquisition from soils, they are logically a target for manipulation to improve crop productivity on soils with poor nutrition (Meister et al 2014)
Shoot dry matter (DM) at 27 days after sowing (DAS) slightly increased with the addition of P, but significant (P < 0.01) responses to P occurred at 48 DAS and at maturity (Table 1)
There were no significant variations in Root system architecture (RSA) traits between the two genotypes; the mean ratios between low P and adequate P for total root length, root surface area, root volume, root tip number and medium root width were 32.5, 31.2, 31.3, 19 and 30%, respectively, greater in RAC875 than in Wyalkatchem (Table S 1)

Summary

Introduction

As roots are the conduit for mineral and water acquisition from soils, they are logically a target for manipulation to improve crop productivity on soils with poor nutrition (Meister et al 2014). Root system architecture (RSA) and morphology are factors used to define properties of root systems; it is vital to identify their favorable traits for. Traits often used for wheat roots are total root length, root surface area, root volume, root angle, number of roots and root diameter (Ahmadi et al 2018; York et al 2018). A number of platforms have been developed for root phenotyping, genetic studies on root traits are hindered due to their complexity, underground location and interactions with the environment (Kuijken et al 2015; Paez-Garcia et al 2015; Topp et al 2016). Suitable methods need to be developed to explore root traits

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