Digital Imaging Delivers Rapid, Consistent Root and Leaf Measurements An Effective Tool in Product Development Plant roots are critical in defining yield in most agricultural ecosystems. Thus, the study of Root Systems Architecture (RSA) has gained considerable interest in recent years. RSA refers to the spatial configuration of the root system and includes root length, root weight, root volume, surface area, root-shoot ratio, branching pattern and horizontal distribution. It can be used to predict crop yield under various growing environments, such as drought, saturated, low fertility or alkaline soils. RSA also is useful to assess the performance of products such as biostimulants, biofertilizers, biofungicides, bioinsecticides and synthetic chemicals applied as seed treatments, soil drench or in-furrow. In the future, optimization of RSA may improve crop productivity, especially under low input or stress conditions. Ultimately, the goal is correlating lab RSA traits with crop productivity. However, low resolution and low throughput approaches for characterizing RSA impede this effort. Spatial evaluation of the root system is not an easy task. The root system of mature plants is quite complex and difficult to measure, while plant development after only 14 days of growth is relatively easy to measure. The primary challenge when evaluating root systems is the limited ability to phenotype and select the desirable traits underground at this early stage of their growth and relate them with growth and yield parameters. Methods such as root drawings, pin boards, auger/cores, rhizotrons, mini-rhizotrons, meso-rhizotrons, horhizotrons, mini-horhizotrons, rhizometers and hydraulic conductance flow meters have been used for root phenotyping in laboratory, greenhouse and field to quantify root growth. As roots changed over time, each method varied in reliability of measurements and results. Many of these methods are arduous, time-consuming and expensive.
ROOTS PERFORM A VARIETY OF FUNCTIONS IN PLANTS. They are responsible for the uptake of nutrients and water, mechanical support for the plants in soil and a site for interactions with beneficial and pathogenic microorganisms in the rhizosphere. Interaction of the roots with their environment depends on their morphology, architecture and distribution in soil profile. Morphology refers to the surface features of the single root, including how the root develops. Roots formed in the embryo are primary and seminal roots in corn/maize and tap or primary roots in legumes. The ones formed later from nodes on shoots are adventitious, secondary or lateral roots. Each type of root plays a different role in plant development and overall growth of plants. Distribution refers to root biomass or how deep it is in the soil, distance and angle from the stem. Morphology and distribution of roots depend on the genetic makeup and physiology of the plant and environmental factors.
Root Digital Imaging
With advancement of technology, other image-based methods are used for measuring and analyzing RSA (Root Systems Architecture) from root diameter and length of individual roots to branching angle and topological depth of the root architecture. Many have the limitation of complex equipment such as Nuclear magnetic resonance (NMR) imaging and X-ray computed tomography. However, the increased resolution of digital scanners associated with dual lighting systems is a reliable alternative.
measurement of healthy plant leaf area or quantifying leaf diseases, insect damage and mycorrhizae. The detailed images also allow for manual counts and visual ratings of nodulation. In summary, such technology offers new opportunities to carry out automated measurement of scanned images without sacrificing accuracy. Image-based analysis has been used successfully to identify cold tolerant, waterlogging, biotic and abiotic stress tolerant cultivars in early-stage breeding efforts. It is also useful to compare performance of biostimulants, humic acid and fertilizers such as PGR and PMGR and to
Automatic image-based root measurements and analysis are now possible through specifically designed software. Such systems can provide morphology, topology, architecture and color analysis of washed roots. Root images are scanned using specific lighting and background to avoid artifacts produced by inconsistent light. This improves rapid and consistent measurements of fine root length, root diameter, root volume and root surface area. These scanners can detect and make corrections for the areas of root overlap and overcome human measurement errors.
map salinized soils. Some examples of successful uses: • A ssess crop vigor in breeding and product differentiation trials. • I dentify cold-tolerant corn hybrids. Corn hybrids designated as cold tolerant had larger, more robust, and branched root systems with well-organized root morphology with higher values for root traits, while cold sensitive hybrids had less organized root structures with low values for root traits (Wijewardana et al., 2015). • I dentify spring green-up cultivars of Bermuda grass. Cold tolerant Bermuda grass cultivar had high stolen dry weight which accelerates spring green-up (Pornaro et al., 2017).
Large sample sizes are more easily evaluated, increasing statistical precision. Other capabilities include
Greenhouse trials compare effects of biostimulant on early plant growth measurements of total emergence and plant height with digital comparisons of root analysis, leaf area, greenness along with root length, area, volume and diameter. Fig 1: Leaf digital analysis
Fig 2: Root digital analysis
Secondary roots (Yellow)
Root length (cm)
Main root
T1
T2 Secondary roots
T2 T1
Main roots (Green)
2
Biostimulant rate
Root Digital Imaging
• I dentify soybean genotypes tolerant to saturated soils. Increased waterlogging of soils decreases root length, total root surface area, total root volume, and root dry weight (Suematsu et al., 2017).
et al., 2011 ), wheat (Tahir et al., 2011), and maize (Jindo et al., 2012). Increased shoot growth has also been reported in tomato (Adani et al., 1998), maize (Eyheraguibel et al., 2008), cucumber (Mora et al., 2010), pepper (Cimrin et al., 2010) and wheat (Tahir et al., 2011).
• R ecognize the importance of root architecture in the productivity of soybean plants, rye, and barley grown under Phosphorus deficient conditions. More root hairs enable additional P uptake which ultimately increases barley yield. (Brown et al., 2012).
• I n rye (Lolium perenne), application of some biostimulant products to young plants significantly increased chlorophyll levels and the regenerative capacity of the roots, an indicator of plant health and increased capacity for absorption of nutrients Russo and Berlyn, 1991).
• I n tomato, a biostimulant increased root development and structure, and resulted in increased absorption of nutrients (Petrozza et al., 2013).
• D rought tolerance in soil: Evaluation of lateral root branching density effects on drought tolerance in maize (Zhan et al., 2015).
• I n wheat, seed inoculation with salt tolerant Azotobacter strains increased plant and root biomass, tissue nitrogen content and grain yield under salt stress (Chaudhary et a l., 2013).
• I n rice, rye and maize root digital imaging has been used to map salinized soils and develop salt tolerant cultivars. In these crops, inhibition of root length has been seen under high salinity (Rodriguez et al., 1997); Rahman et al., 2001; Ogawa et al., 2006).
• E nhancement of lateral roots and seedling root growth by humic acid has been reported in Lantana camara (Costa et al., 2008), Arabidopsis (Dobbss et al., 2010), pepper (Cimrin et al., 2010), tomato (Canellas
The scientific and practical experience offered by AgriThority Ž includes Prescriptive Response™ Development services for evaluation of crop inputs or new technologies. From biostimulants, biopesticides and biofertilizers to synthetic chemicals (fungicides, insecticides and herbicides), the use of digital imagery improves the plant and root health evaluations from lab, greenhouse, small plot and large fields. AgriThority experts conduct image-based root and plant evaluations on corn/ maize, soybean, wheat and many other crops to evaluate impact of new technologies. Many products applied as seed and soil treatments significantly improve RSA (root length, diameter, projected area, volume and surface area) and nodulation in addition to leaf parameters. An advantage of the digital imagery is during the pronounced response to treatments that are most visible in two to three weeks after emergence. Characterization of each treatment’s effects on plant growth is captured at the initial stage of crop development i.e., 30 days after emergence when yield potential is determined.
t ke o n ar si M pan Ex
R e g ul a t o r y Business Development
Market De velopme nt
New Uses
3
Root Digital Imaging
digital image technology increased effectiveness of field experiments at later stages. Tapping unexplored opportunities within RSA for rapid, stable, and enhanced productivity is more precise and reliable when digital imagery tools are used for early-season root and shoot analysis. RSA is an excellent way to evaluate the performance of different products on several crops in the greenhouse with results available in a very short period providing a cost-effective way to increase effectiveness of field experiments at later stages. AgriThority has in-house lab facilities and experienced experts for root and shoot evaluations using image-based technology to determine
In an AgriThority-conducted greenhouse study an organic fertilizer significantly increased root length, root diameter, root volume and root surface area in early stages of corn plants compared to the grower standard practice (GSP) as evident from digital root analysis images (see Fig 3 and 4). Fig 3. Grower standard practice
Fig 4. Organic fertilizer
the effects of seed and soil applied technologies.
In another greenhouse study to evaluate the compatibility of a biostimulant with biofungicide, digital root images data on root length, surface area, and volume showed that there was no compatibility between a biostimulant and fungicide seed treatment (see Fig 5). Based on the results of these early greenhouse studies, further field studies were modified for increased effectiveness.
Conclusion: Root morphology and root architecture are useful characteristics to be evaluated by precise and reliable digital imagery tools. • I n breeding programs and for selecting better cultivars to increase crop yield under different environmental conditions or limited resources. • T o evaluate the performance of biofertilizers, biostimulants and chemicals as seed or soil application on root architecture, leaf parameters and nodulation, where applicable.
Results of these and other studies which AgriThority conducts clearly show that investment in early-stage product development in greenhouse trials using
Early detection of compatibility issues with biostimulant added to fungicide improves continued development efforts.
Biostimulant at optimal rate
Biostimulant + Fungicide Fig 5. Images of roots of corn plants from seeds treated with biostimulant alone and in combination with fungicide
4
Root Digital Imaging
References Adani, F., Genevini, P., Zaccheo, P. and Zocchi, G. 1998. The effect of commercial humic acid on tomato plant growth and mineral nutrition. J Plant Nutr. 21: 561575. https://doi.org/10.1080/01904169809365424
Ogawa, A., Kitamichi, K., Toyofuku, K. and Kawashima, C. 2006. Quantitative analysis of cell division and cell death in seminal root of rye under salt stress. Plant Prod Sci. 9: 56-64. https://doi.org/10.1626/pps.9.56
Brown, L.K., George, T.S., Thompson, J.A., Wright, G., Lyon, J., Dupuy, L., Hubbard, S.F. and White, P.J. 2012. What are the implications of variation in root hair length on tolerance to phosphorus deficiency in combination with water stress in barley (Hordeum vulgare)? Ann Bot. 110: 319-328. https://doi.org/10.1093/aob/mcs085
Petrozza, A., Summerer, S., Tommaso, G. Di, Tommaso, D. Di and Piaggesi, A. 2013. Evaluation of the effect of Radifarm® treatment on the morpho-physiological characteristics of root systems via image analysis. Acta Hortic. 1009: 149-153. https://doi.org/10.17660/ActaHortic.2013.1009.18
Canellas, L.P., Dantas, D.J., Aguiar, N.O., Peres, L.E.P., Zsogin, A., Olivares, F.L., Dobbss, L.B., Facanha, A.R., Nebbioso, A. and Piccolo, A. 2011. Probing the hormonal activity of fractionated molecular humic components in tomato auxin mutants. Ann Appl Biol. 159: 202-211. https://doi.org/10.1111/j.1744-7348.2011.00487.x
Pornaro, C., Macolino, S., Menegon, A. and Richardson, M. 2017. WinRHIZO technology for measuring morphological traits of bermudagrass stolons. Agron J. 109: 30073010. https://doi.org/10.2134/agronj2017.03.0187
Chaudhary, D., Narula, N., Sindhu, S. S. and Behl, R. K. 2013. Plant growth stimulation of wheat (Triticum aestivum L.) by inoculation of salinity tolerant Azotobacter strains. Physiol Mol Biol Plants. 19: 515-519. https://doi.org/10.1007/s12298-0130178-2 Cimrin, K.M., Türkmen, O., Turan, M. and Tuncer, B. 2010. Phosphorus and humic acid application alleviate salinity stress of pepper seedling. Afr J Biotechnol. 9: 5845-5851. https://www.ajol.info/index.php/ajb/article/view/92903 Costa, G., Labrousse, P., Bodin, C., Lhernould, S., Carlue, M., Authier, F. and Krausz, P. 2008. Effects of humic substances on the rooting and development of woody plant cuttings. Acta Hortic. 779: 255-261. https://doi.org/10.17660/ActaHortic.2008.779.31 Dobbss, L.B., Canellas, L.P., Olivares, F.L., Aguiar, N.O., Peres, L.E.P., Azevedo, M., Spaccini, R., Piccolo, A. and Facanha, A.R. 2010. Bioactivity of chemically transformed humic matter from vermicompost on plant root growth. J Agric Food Chem. 58: 3681-3688. https://doi.org/10.1021/jf904385c Eyheraguibel, B., Silvestre, J. and Morard, P. 2008. Effects of humic substances derived from organic waste enhancement on the growth and mineral nutrition of maize. Bioresour Technol. 99: 4206-4212. https://www.sciencedirect.com/science/ article/abs/pii/S0960852407007092?via%3Dihub Jindo, K., Martim, S.A., Navarro, E.C., Perez-Alfocea, F., Hernandez, T., Garcia C., Aguiar, N.O. and Canellas, L.P. 2012. Root growth promotion by humic acids from composted and non-composted urban organic wastes. Plant Soil 353: 209-220. https://doi.org/10.1007/s11104-011-1024-3 Mora, V., Bacaicoa, E., Zamarreño, A.M., Aguirre, E., Garmina, M., Fuentes, M. and García-Mina Jose-Maria. 2010. Action of humic acid on promotion of cucumber shoot growth involves nitrate-related changes associated with the root-to-shoot distribution of cytokinins, polyamines and mineral nutrients. J Plant Physiol. 167: 633-642. http://doi.org/10.1016/j.jplph.2009.11.018
Rahman, S.M., Matsumuro, T., Miyake, H. and Takeoka, Y. 2001. Effects of salinity stress on the seminal root tip ultrastructures of rice seedlings (Oryza sativa L.). Plant Prod Sci. 4: 103-111. https://doi.org/10.1626/pps.4.103 Rodriguez, H.G., Roberts, J.K.M., Jordan, W.R. and Drew, M.C. 1997. Growth, water relations and accumulation of organic and inorganic solutes in roots of maize seedlings during salt stress. Plant Physiol. 113: 881-893. https://doi.org/10.1104/ pp.113.3.881 Russo, R. and Berlyn, G.P. 1991. The use of organic biostimulants to help low input sustainable agriculture. J Sustain Agr. 1: 19-42. https://www.tandfonline.com/doi/ abs/10.1300/J064v01n02_04 Suematsu, K., Abiko, T., Nguyen, V.L. and Mochizuki, T. 2017. Phenotypic variation in root development of 162 soybean accessions under hypoxia condition at the seedling stage. Plant Prod Sci. 20: 323-335. https://www.tandfonline.com/doi/full/1 0.1080/1343943X.2017.1334511 Tahir, M. M., Khurshid, M., Khan, M. Z., Abbasi, M. K. and Kazmi, M. H. 2011. Lignite-derived humic acid effect on growth of wheat plants in different soils. Pedosphere 2: 124-131. https://www.sciencedirect.com/science/article/abs/pii/ S1002016010600872?via%3Dihub Wijewardana, C., Hock, M., Henry, B. and Reddy, K.R. 2015. Screening corn hybrids for cold tolerance using morphological traits for early season seeding. Crop sci. 55: 851-867. https://doi.org/10.2135/cropsci2014.07.0487 Zhan, Ai., Schneider, H. and Lynch, J.P. 2015. Reduced lateral root branching density improves drought tolerance in maize. Plant Physiol. 168: 1603-1615. https://doi.org/10.1104/pp.15.00187
About the Authors Madhu Jindal, Ph.D., Research Manager/Analyst NORAM, works in the digital imagery lab and contributes to the technical review of field trial reports. Formerly a senior wheat pathologist at Punjab Agricultural university, Jindal has more than 30 years of disease research experience with multiple row crops, specialty and horticultural plants. Project Contributions by Ignacio Colonna, Research Manager, LATAM, an experienced researcher and a proven research operations manager. He oversees all lab, greenhouse and field research operations, as well as data analysis and analytics projects in Latin America for AgriThority clients.
Digital imaging and evaluation is one of our many product and field development services. See What We Do on our website. 11125 N Ambassador Dr Kansas City, MO 64153-2033 United States
Author :
Madhu Jindal, Ph.D. Contributor:
Ignacio Colonna
To Move Your Innovation to Market, add more Development to your R & D efforts with AgriThority. phone: +1.816.891.0916 toll free: +1.888.891.0511
© 2020 AgriThority ® AgriThority is a registered trademark and Prescriptive Response™ is a trademark of AgriThority ® LLC
AgriThority.com info@AgriThority.com
