Temporal phenotypic variation of spinach root traits and its relation to shoot performance

Abstract

Abstract The root system is important for the growth and development of spinach. To reveal the temporal variability of the spinach root system, root traits of 40 spinach accessions were measured at three continuous stages in this study using a non-destructive and non-invasive root analysis system. Results showed that root traits had higher variations than shoot traits among spinach accessions, and the trait of relative growth rate of total root length had the largest coefficients of variation across the three imaging times. Most of the root traits were correlated between the different stages, but the correlations decreased with increasing sampling intervals. At the early stage, only tap root length was weakly correlated with shoot traits (plant height, leaf width, and object area), whereas at the later stage, root fresh weight, total root length, and root area were strongly correlated with shoot biomass-related traits. Plants with halberd-shaped leaves tended to have stronger root systems than those with nearly orbicular-shaped leaves. The 40 spinach accessions were classified into five subgroups with different growth dynamics of the primary and lateral roots. Our results demonstrated the potential of in-situ phenotyping to assess dynamic root growth in spinach and provide new perspectives for biomass breeding based on root system ideotypes.