Assessing phosphorus efficiency and tolerance in maize genotypes with contrasting root systems at the early growth stage using the semi‐hydroponic phenotyping system

Abstract

Background: Development of an evaluation tool to determine genotypic variation in phosphorus (P) utilization efficiency is essential to ensure crop productivity and farmers' income under low P environments.Aims: This study aimed to develop an evaluation tool to determine genotypic variation in low-P tolerance and P use efficiency under low P environments.Methods: Root response and P efficiency traits in 20 maize genotypes with contrasting root systems were assessed 32 days after transplanting into the semi-hydroponic root phenotyping system under low P (10 µM) or optimal P (200 µM) supply.Results: Compared to optimal P, low P supply increased root-to-shoot biomass ratio by 48.7% (shoot dry weight decreased by 20.0% and root dry weight increased by 20.6%).Low P supply increased total root length by 17.8% but decreased primary root depth, with no significant change in lateral root number across all genotypes. Low P stress enhanced P utilization efficiency. Based on genotypic variation and correlations among the 17 measured plant traits in response to low P stress, nine traits were converted to low-P tolerance coefficients (LPTC), compressed by principal component analysis. The three principal component scores were extracted for hierarchical cluster analysis and classified the 20 genotypes into three groups with different P efficiency, including two P-efficient genotypes and nine P-inefficient genotypes. Conclusions:The study demonstrated genotypic variation in response to low P stress. The P-efficient genotypes with higher LPTC values better adapted to low P environments by adjusting root architecture and re-distributing P and biomass in plant organs. The systematic cluster analysis using selected traits and their LPTC values can be used as an evaluation tool in assessing P efficiency among the genotypes. K E Y W O R D Slow-P tolerant coefficients (LPTC), low P stress, maize, phosphorus efficiency, root system architecture, root-to-shoot mass ratioThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.