Screening of Soybean Genotypes Based on Root Morphology and Shoot Traits Using the Semi-Hydroponic Phenotyping Platform and Rhizobox Technique

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.

Recent advances in methods for in situ root phenotyping

“…Hydroponics is a high-throughput phenotype screening and identification method which involves culturing plants in a solid support device containing a nutrient solution with essential nutrients for plant growth. Hydroponic phenotyping system has been used to characterize root morphological traits at the early growth stage of various crop species, including soybean ( Chen, 2021 ; Salim et al, 2021 ), barley ( Wang et al, 2021 ), wheat ( Jeudy et al, 2016 ; Rumesh et al, 2019 ; Chen et al, 2020 ), and maize ( Qiao et al, 2019 ). Jeudy et al (2016) developed a new tool for high throughput imaging of root features based on a form of hydroponic called RhizoTubes.…”

Growth and Yield of Three Soybean Cultivars by the Nutritional Effect of Zinc and Arginine

“…The superiority of the Lee variety may be due to its high efficiency in converting photosynthetic products from the vegetative part of the plant in favor of root growth, increasing division, and elongation of its cells, and then increasing root length. In the same direction as [11,21] that the varieties differ among themselves in root length. It appears from the results of the triple interaction that the Lee cultivar, with the effect of foliar feeding with zinc concentration 100 mg L -1 and arginine 80 mg L -1 concentration, gave the highest average root length of 37.55 while Shaima, in the comparison treatment of zinc and arginine, gave the lowest root length rate of 37.55 cm.…”

Chromosome groups 5, 6 and 7 harbor major quantitative trait loci controlling root traits in bread wheat (Triticum aestivum L.)

“…In our recent study, root trait variability of 184 bread wheat genotypes originating from 37 countries was characterized in the same semi-hydroponic phenotyping system (Chen et al, 2020), followed by validation of genotypes with contrasting root systems in soil-filled rhizoboxes (Figueroa-Bustos et al, 2018). The consistent ranking of genotypes for some important root traits in the semi-hydroponic system and soil conditions indicates the reliability of the phenotyping study for root studies, as confirmed in other crop species, such as narrow-leafed lupin (Chen et al, 2011a;Chen et al, 2014), barley (Wang et al, 2021), and soybean (Liu et al, 2021;Salim et al, 2022). The wheat lines used in this study will be examined further under the field conditions.…”