Root system traits are important for crop production. This study characterized the soybean root system by analyzing position markers and digital images. Soybean genotypes were grown in a growth pouch, and their root systems were photographed every few days using a digital camera. Image analysis was performed to segment the roots and measure root length. Three genotypes widely used to provide reference genomes or as major breeding materials were used for Experiment 1. The root dry weight of ‘Williams 82’ at 13 days after transplant (DAT) did not differ significantly with that of ‘Enrei’. However, the root length of ‘Williams 82’ at 8–11 DAT was significantly smaller, whereas that at 13 DAT was comparable with that of ‘Enrei’. Determining the differences by sampling date and root segment revealed that ‘Williams 82’ developed its root system evenly from the middle and bottom segments at 8 DAT, whereas those of ‘Enrei’ and ‘Peking’ developed unevenly from only the bottom segment. Because the genotypes for Experiment 1 had different seed sizes and extent of root elongation, the genotypes with similar seed sizes were used for Experiment 2. Compared with ‘U 1042-1’, ‘COL/PAK/1989/IBPGR/2326(1)’ showed more elongation in the middle root segment at 8–11 DAT. Image analysis enabled a more in-depth investigation of root system development over time and by root segment.

Drought limits water availability and negatively impacts rice growth. One of the strategies to overcome drought stress is the genetic improvement of root traits by marker-assisted selection (MAS). Using the MAS strategy, pyramiding quantitative trait loci (QTLs) efficiently stacks multiple QTLs. To elucidate the effects of pyramiding root QTLs on shoot production under drought, we used near-isogenic lines (NILs) and pyramided lines (PYLs), introducing single or multiple QTLs derived from Kinandang Patong (upland rice) into IR64 (lowland rice). We selected one QTL from each root morphological trait: root growth angle (DRO1), root thickness (Sta1), root length (qRL6.1), and root volume (qFSR4). We evaluated the effects of pyramiding root QTLs on root system architecture (RSA). In the basket method and 3D imaging by X-ray computed tomography, all NIL and PYLs with DRO1 showed robustly steeper root growth angle. In a hydroponic culture assay, root length QTL qRL6.1 increased maximum root length. In a lysimeter experiment, root volume QTL qFSR4 increased root volume per stem. Next, we examined the NILs and PYLs for shoot biomass production under drought conditions in lysimeter and field experiments. Two lines (DRO1-NIL and Sta1+DRO1-PYL) had a higher shoot biomass production under drought than IR64. DRO1-NIL exhibited deeper RSAs and increased water uptake compared to IR64. Sta1+DRO1-PYL was not as deep as DRO1-NIL but had a higher normalized difference vegetation index, lower canopy temperature, and higher shoot biomass in the field experiment. In summary, DRO1 plays a critical role in RSA, and pyramiding Sta1 with DRO1 increases shoot biomass during drought. This suggests the pyramiding of root QTLs could improve RSA and enhance biomass production under drought stress.

Studying the growth of soybean roots in hydroponic culture provides a means to avoid issues caused by the heterogeneity and opaqueness of soil. In this study, we applied three salt-tolerant soybean near isogenic lines (NILs) and three corresponding salt-sensitive NILs for hydroculture with ten different salt concentrations. A digital camera was utilized to continuously capture RGB side-view images of hydroponically grown soybean roots. To extract two-dimensional information of root area from the side-view images, we applied a machine learning-based method, the trainable WEKA segmentation. The root volume was estimated by raising the root area to the power of 3/2 and applying a coefficient. Additionally, skeleton length of root was obtained from the bottom 30% of images with minimal root overlap to calculate the average root diameter. The total root length was estimated from the root volume and the average root diameter then applying a coefficient. The results indicate that the coefficients of root volume and total root length ranged from 0.0164 to 0.0291 and 0.0449 to 0.0874, respectively, for the three correspondent NILs. Using these coefficients, the root volume and total root length were estimated with the root mean square error (RMSE) ranging from 1.87 to 5.32 cm³ and 0.67 to 2.32 × 10³ cm, respectively. The estimation results clearly demonstrated the differences across NILs and treatments even though ten salt treatments caused different root morphologies. This method may contribute to further understanding the dynamic changes in root traits under various abiotic stresses.

Medicinal plants are used to treat several illnesses linked to oxidative stress. The herbaceous annual plant Heliotropium indicum L. is found in Asia and is widely used in traditional medicine. The investigation aimed to evaluate the antioxidant properties of five solvent extracts (hexane, chloroform, ethyl acetate, methanol, and aqueous) of Heliotropium indicum L. roots. The antioxidant compounds in the ethyl acetate extract were also identified. The ethyl acetate root extract demonstrated significant antioxidant properties in DPPH radical scavenging and reducing power assays. Shimadzu-QP2020 GC-MS was used to assess the phytochemical composition of the ethyl acetate root extract. The extract contained chemicals whose mass spectra matched those in the National Institute of Standards and Technology (NIST) library. Conventionally, the combined analytical method of gas chromatography-mass spectroscopy (GC-MS) is employed to identify and ascertain the substances in the sample. The functional groups in the ethyl acetate extract were analyzed by FTIR spectroscopy. The GC-MS analysis of ethyl acetate root extract identified forty-two compounds in total, with the highest area percentage (23.11%) being Cholesta-22,24-dien-5-ol, 4,4-dimethyl- and the lowest area percentage (0.26%) being 7,9-Di-tert-butyl-1-oxaspiro (4,5) deca-6,9-diene-2,8-dione. The GC-MS investigation revealed twelve major compounds. This work is the first to report on the antioxidant, statistical analysis using ANOVA and Post-hoc Tukey’s HSD test (SPSS 27.0 software), GC-MS, and FTIR analyses of Heliotropium indicum L. ethyl acetate root extract. The current study offers a foundation for natural chemicals that are safer and less expensive to combat illnesses linked to oxidative stress.