Abstract
Root-system architecture is vital for improving soybean (Glycine max L.) growth and nutrient uptake. We characterised root-system architecture and shoot traits of 30 soybean genotypes in a semi-hydroponic system 35 days after sowing (DAS) and validated eight genotypes with contrasting root-system architecture in 1.5 m-deep rhizoboxes at the flowering stage. Among them, two genotypes were selected for evaluation through to maturity. Abundant variation (coefficient of variation values ≥ 0.25) was observed in 11 of 13 measured roots and shoot traits during the early growth stage. After late growth stages, strong positive correlations were found between root traits and shoot traits, except for specific root length and diameter. Seed yield and yield traits at final harvest significantly differed between two contrasting soybean genotypes. The large-rooted genotype had a higher harvest index than the small-rooted genotype. Soybean genotypes with larger root systems had a long time to flowering than those with smaller root systems. Genotypes with large-root systems had 106% more leaf area, and 245% more shoot dry weight than those with small systems, presumably due to high canopy photosynthesis to supply the demand for carbon assimilates to roots. Total root length, and root: shoot ratio-traits data collected in the rhizobox study, strongly correlated with the same traits in the semi-hydroponic phenotyping system. We found genetic variation and phenotypic plasticity in other root and shoot traits such as taproot depth, root dry weight, specific root length, and average root diameter among the tested genotypes. Phenology, particularly time to flowering, was associated with root system size. Some root and shoot traits in the semi-hydroponic phenotyping system at the seedling stage produced similar rankings at the later phenological (flowering) stage when grown in the soil-filled rhizoboxes. The soybean genotypes characterised by vastly different root traits could be used for further glasshouse and field studies to improve adaptation to drought and other specific environments.
Highlights
Introduction distributed under the terms andRoots are the primary organ for transferring soil resources to other plant parts, thereby controlling productivity [1]
Developed and validated semi-hydroponic phenotyping systems [6] have been used for high-throughput phenotyping of root morphological traits in several crop species at the early growth stage including narrow-leafed lupin [7], chickpea [8], wheat [9], barley [10] and soybean [11]
Many advances have been made in recent years to measure root traits, including easier, faster, reproducible, and more-descriptive techniques for wheat-root growth [12]
Summary
Introduction distributed under the terms andRoots are the primary organ for transferring soil resources to other plant parts, thereby controlling productivity [1]. Root-system architecture refers to the spatial configuration of the entire root system It is generally quite complex and is different from morphology, root branching, and distribution [2]. Different methods and techniques for observing, studying, and quantifying root growth have been reported in the past nine decades. Developed and validated semi-hydroponic phenotyping systems [6] have been used for high-throughput phenotyping of root morphological traits in several crop species at the early growth stage including narrow-leafed lupin [7], chickpea [8], wheat [9], barley [10] and soybean [11]. Many advances have been made in recent years to measure root traits, including easier, faster, reproducible, and more-descriptive techniques for wheat-root growth [12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
