Name: an optimized rhizobox protocol to visualize root growth and responsiveness to localized nutrients
Uploaded: 2018-10-22T15:00:00
Description: Watch this Scientific Journal Video about An Optimized Rhizobox Protocol to Visualize Root Growth and Responsiveness to Localized Nutrients at JoVE.com

The authors would like to acknowledge anonymous reviewers for their feedback, as well as J.C. Cahill and Tan Bao for initial guidance on developing the rhizobox protocol. Funding was provided by the Foundation for Food and Agriculture Research, the US Department of Agriculture (USDA) National Institute of Food and Agriculture, Agricultural Experiment Station Project CA-D-PLS-2332-H, to A.G. and by the UC Davis Department of Plant Sciences through a fellowship to J.S.

1. Preparation of the Front and Back Panels, and Spacers
<ol>
	<li>Prepare the front and back panels.
	<ol>
		<li>Cut two pieces of clear 0.635 cm thick acrylic to 40.5 cm wide by 61 cm long per box or purchase pre-cut pieces (see Table of Materials).</li>
		<li>Using a drill bit designed for acrylic, drill holes 0.635 cm in diameter 1.3 cm from the side edges at 2.5, 19, 38, and 53.3 cm from the top. Drill holes 1.3 cm from the bottom edge at 2.5, 20.3, and 38 cm from the left side (<strong class="xfi...

<ol>
	<li>Hodge, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Roots:+The+Acquisition+of+Water+and+Nutrients+from+the+Heterogeneous+Soil+Environment.">Roots: The Acquisition of Water and Nutrients from the Heterogeneous Soil Environment.</a> Progress in Botany 71. , 307-337 (2010).</li><li>Grossman, J. D., Rice, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+root+plasticity+responses+to+variation+in+soil+nutrient+distribution+and+concentration.">Evolution of root plasticity responses to variation in soil nutrient distribution and concentration.</a> Evolutionary Applications. 5 (8), 850-857 (2012).</li><li>Zhang, H., Forde, B. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Arabidopsis+MADS+box+gene+that+controls+nutrient-induced+changes+in+root+architecture.">An Arabidopsis MADS box gene that controls nutrient-induced changes in root architecture.</a> Science. 279 (5349), 407-409 (1998).</li><li>Hodge, A., Stewart, J., Robinson, D., Griffiths, B. S., Fitter, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Competition+between+roots+and+soil+micro-organisms+for+nutrients+from+nitrogen-rich+patches+of+varying+complexity.">Competition between roots and soil micro-organisms for nutrients from nitrogen-rich patches of varying complexity.</a> Journal of Ecology. 88 (1), 150-164 (2000).</li><li>Trachsel, S., Kaeppler, S. M., Brown, K. M., Lynch, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shovelomics:+high+throughput+phenotyping+of+maize+(Zea+mays+L.)+root+architecture+in+the+field.">Shovelomics: high throughput phenotyping of maize (Zea mays L.) root architecture in the field.</a> Plant and Soil. 341 (1-2), 75-87 (2011).</li><li>Rogers, E. D., Monaenkova, D., Mijar, M., Nori, A., Goldman, D. I., Benfey, P. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=X-ray+computed+tomography+reveals+the+response+of+root+system+architecture+to+soil+texture.">X-ray computed tomography reveals the response of root system architecture to soil texture.</a> Plant Physiology. , (2016).</li><li>Groleau-Renaud, V., Plantureux, S., Guckert, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+mechanical+constraint+on+nodal+and+seminal+root+system+of+maize+plants.">Effect of mechanical constraint on nodal and seminal root system of maize plants.</a> Comptes Rendus De L Academie Des Sciences Serie Iii-Sciences De La Vie-Life Sciences. 321 (1), 63-71 (1998).</li><li>Lin, Y., Allen, H. E., Di Toro, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Barley+root+hair+growth+and+morphology+in+soil,+sand,+and+water+solution+media+and+relationship+with+nickel+toxicity.">Barley root hair growth and morphology in soil, sand, and water solution media and relationship with nickel toxicity.</a> Environmental Toxicology and Chemistry. 35 (8), 2125-2133 (2016).</li><li>Wenzel, W. W., Wieshammer, G., Fitz, W. J., Puschenreiter, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+rhizobox+design+to+assess+rhizosphere+characteristics+at+high+spatial+resolution.">Novel rhizobox design to assess rhizosphere characteristics at high spatial resolution.</a> Plant and Soil. 237 (1), 37-45 (2001).</li><li>Spohn, M., Carminati, A., Kuzyakov, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soil+zymography+-+A+novel+in+situ+method+for+mapping+distribution+of+enzyme+activity+in+soil.">Soil zymography - A novel in situ method for mapping distribution of enzyme activity in soil.</a> Soil Biology and Biochemistry. 58, 275-280 (2013).</li><li>Vollsnes, A. V., Futsaether, C. M., Bengough, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+rhizosphere+particle+movement+around+mutant+maize+roots+using+time-lapse+imaging+and+particle+image+velocimetry.">Quantifying rhizosphere particle movement around mutant maize roots using time-lapse imaging and particle image velocimetry.</a> European Journal of Soil Science. 61 (6), 926-939 (2010).</li><li>Hewitt, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Sand and Water Culture Methods Used in the Study of Plant Nutrition. , (1966).</li><li>Choudhary, M. I., Shalaby, A. A., Al-Omran, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+holding+capacity+and+evaporation+of+calcareous+soils+as+affected+by+four+synthetic+polymers.">Water holding capacity and evaporation of calcareous soils as affected by four synthetic polymers.</a> Communications in Soil Science and Plant Analysis. 26 (13-14), 2205-2215 (1995).</li><li>Bakker, P. A. H. M., Berendsen, R. L., Doornbos, R. F., Wintermans, P. C. A., Pieterse, C. M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+rhizosphere+revisited:+root+microbiomics.">The rhizosphere revisited: root microbiomics.</a> Frontiers in Plant Science. 4, 2013 (2013).</li><li>McNear, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Rhizosphere+-+Roots,+Soil,+and+Everything+In+Between.">The Rhizosphere - Roots, Soil, and Everything In Between.</a> Nature Education Knowledge. 4 (3), 1 (2013).</li><li>Ortas, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+the+extent+of+rhizosphere+soil.">Determination of the extent of rhizosphere soil.</a> Communications in Soil Science and Plant Analysis. 28 (19-20), 1767-1776 (1997).</li><li>. Carbon (13C) and Nitrogen (15N) Sample Preparation Available from: <a target="_blank" href="https://stableisotopefacility.ucdavis.edu/13cand15nsamplepreparation.html">https://stableisotopefacility.ucdavis.edu/13cand15nsamplepreparation.html</a> (2018)</li><li>Barraclough, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=15N+isotope+dilution+techniques+to+study+soil+nitrogen+transformations+and+plant+uptake.">15N isotope dilution techniques to study soil nitrogen transformations and plant uptake.</a> Fertilizer research. 42 (1-3), 185-192 (1995).</li><li>Belter, P. R., Cahill, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disentangling+root+system+responses+to+neighbours:+identification+of+novel+root+behavioural+strategies.">Disentangling root system responses to neighbours: identification of novel root behavioural strategies.</a> AoB PLANTS. 7, (2015).</li><li>Nagel, K. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GROWSCREEN-Rhizo+is+a+novel+phenotyping+robot+enabling+simultaneous+measurements+of+root+and+shoot+growth+for+plants+grown+in+soil-filled+rhizotrons.">GROWSCREEN-Rhizo is a novel phenotyping robot enabling simultaneous measurements of root and shoot growth for plants grown in soil-filled rhizotrons.</a> Functional Plant Biology. 39 (11), 891-904 (2012).</li><li>Adu, M. O., Yawson, D. O., Bennett, M. J., Broadley, M. R., Dupuy, L. X., White, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+scanner-based+rhizobox+system+enabling+the+quantification+of+root+system+development+and+response+of+Brassica+rapa+seedlings+to+external+P+availability.">A scanner-based rhizobox system enabling the quantification of root system development and response of Brassica rapa seedlings to external P availability.</a> Plant Root. 11, 16-32 (2017).</li><li>Neumann, G., George, T. S., Plassard, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strategies+and+methods+for+studying+the+rhizosphere-the+plant+science+toolbox.">Strategies and methods for studying the rhizosphere-the plant science toolbox.</a> Plant and Soil. 321 (1-2), 431-456 (2009).</li><li>Bodner, G., Alsalem, M., Nakhforoosh, A., Arnold, T., Leitner, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RGB+and+Spectral+Root+Imaging+for+Plant+Phenotyping+and+Physiological+Research:+Experimental+Setup+and+Imaging+Protocols.">RGB and Spectral Root Imaging for Plant Phenotyping and Physiological Research: Experimental Setup and Imaging Protocols.</a> JoVE (Journal of Visualized Experiments). (126), e56251-e56251 (2017).</li><li>Kuchenbuch, R. O., Ingram, K. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Image+analysis+for+non-destructive+and+non-invasive+quantification+of+root+growth+and+soil+water+content+in+rhizotrons.">Image analysis for non-destructive and non-invasive quantification of root growth and soil water content in rhizotrons.</a> Journal of Plant Nutrition and Soil Science. 165 (5), 573-581 (2002).</li><li>Dresb&#248;ll, D. B., Thorup-Kristensen, K., McKenzie, B. M., Dupuy, L. X., Bengough, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Timelapse+scanning+reveals+spatial+variation+in+tomato+(Solanum+lycopersicum+L.)+root+elongation+rates+during+partial+waterlogging.">Timelapse scanning reveals spatial variation in tomato (Solanum lycopersicum L.) root elongation rates during partial waterlogging.</a> Plant and Soil. 369 (1-2), 467-477 (2013).</li><li>Wu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RhizoChamber-Monitor:+a+robotic+platform+and+software+enabling+characterization+of+root+growth.">RhizoChamber-Monitor: a robotic platform and software enabling characterization of root growth.</a> Plant Methods. 14 (1), 44 (2018).</li><li>Rogers, S. W., Moorman, T. B., Ong, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+In+Situ+Hybridization+and+Micro-autoradiography+Applied+to+Ecophysiology+in+Soil.">Fluorescent In Situ Hybridization and Micro-autoradiography Applied to Ecophysiology in Soil.</a> Soil Science Society of America Journal. 71 (2), 620-631 (2007).</li><li>Eickhorst, T., Tippk&#246;tter, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+microorganisms+in+undisturbed+soil+by+combining+fluorescence+in+situ+hybridization+(FISH)+and+micropedological+methods.">Detection of microorganisms in undisturbed soil by combining fluorescence in situ hybridization (FISH) and micropedological methods.</a> Soil Biology and Biochemistry. 40 (6), 1284-1293 (2008).</li><li>Spohn, M., Kuzyakov, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+of+microbial-+and+root-derived+phosphatase+activities+in+the+rhizosphere+depending+on+P+availability+and+C+allocation+-+Coupling+soil+zymography+with+14C+imaging.">Distribution of microbial- and root-derived phosphatase activities in the rhizosphere depending on P availability and C allocation - Coupling soil zymography with 14C imaging.</a> Soil Biology and Biochemistry. 67, 106-113 (2013).</li><li>Lv, G., Kang, Y., Li, L., Wan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+irrigation+methods+on+root+development+and+profile+soil+water+uptake+in+winter+wheat.">Effect of irrigation methods on root development and profile soil water uptake in winter wheat.</a> Irrigation Science. 28 (5), 387-398 (2010).</li><li>Asseng, S., Ritchie, J. T., Smucker, A. J. M., Robertson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Root+growth+and+water+uptake+during+water+deficit+and+recovering+in+wheat.">Root growth and water uptake during water deficit and recovering in wheat.</a> Plant and Soil. 201 (2), 265-273 (1998).</li><li>Hernandez-Ramirez, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Root+Responses+to+Alterations+in+Macroporosity+and+Penetrability+in+a+Silt+Loam+Soil.">Root Responses to Alterations in Macroporosity and Penetrability in a Silt Loam Soil.</a> Soil Science Society of America Journal. 78 (4), 1392-1403 (2014).</li><li>Zhang, Y. L., Wang, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soil+enzyme+activities+with+greenhouse+subsurface+irrigation.">Soil enzyme activities with greenhouse subsurface irrigation.</a> Pedosphere. 16 (4), 512-518 (2006).</li><li>Robinson, D., Hodge, A., Griffiths, B. S., Fitter, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+root+proliferation+in+nitrogen-rich+patches+confers+competitive+advantage.">Plant root proliferation in nitrogen-rich patches confers competitive advantage.</a> Proceedings of the Royal Society of London B: Biological Sciences. 266 (1418), 431-435 (1999).</li><li>Lobet, G., Draye, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+scanning+procedure+enabling+the+vectorization+of+entire+rhizotron-grown+root+systems.">Novel scanning procedure enabling the vectorization of entire rhizotron-grown root systems.</a> Plant Methods. 9, 1 (2013).</li><li>Swarup, R., Wells, D. M., Bennett, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Root+Gravitropism.">Root Gravitropism.</a> Plant Roots: The Hidden Half. , (2013).</li><li>Smit, A. L., Bengough, A. G., Engels, C., van Noordwijk, M., Pellerin, S., van de Geijn, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Root Methods: A Handbook. , (2000).</li><li>van Dusschoten, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+3D+Analysis+of+Plant+Roots+Growing+in+Soil+Using+Magnetic+Resonance+Imaging1[OPEN].">Quantitative 3D Analysis of Plant Roots Growing in Soil Using Magnetic Resonance Imaging1[OPEN].</a> Plant Physiology. 170 (3), 1176-1188 (2016).</li><li>Metzner, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+comparison+of+MRI+and+X-ray+CT+technologies+for+3D+imaging+of+root+systems+in+soil:+potential+and+challenges+for+root+trait+quantification.">Direct comparison of MRI and X-ray CT technologies for 3D imaging of root systems in soil: potential and challenges for root trait quantification.</a> Plant Methods. 11, 17 (2015).</li></ol>

The rhizoboxes described in this protocol can be used to answer varied questions in root and rhizosphere science, and have found diverse uses elsewhere10,20,21,22,23,24,25. Other researchers have captured time-lapse images of rhizoboxes21,...

Although often overlooked compared to their aboveground counterparts, roots play a critical role in plant nutrient acquisition. Given the substantial carbon cost of root construction and maintenance, plants have evolved mechanisms to develop roots only where foraging is worth the investment. Root systems can thus efficiently and dynamically mine resource patches by proliferating in hotspots, upregulating rates of uptake, and rapidly translocating nutrients to the phloem for further transport1. Plasticity responses can vary widely among plant species or genotypes2,3 and depending on the chemical form of the nutrient involved4,5. Variation in root plasticity should be explored further, as understanding complex root responses to heterogeneous soil resources could inform breeding and management strategies to increase nutrient use efficiency in agriculture.
Despite its necessity and relevance for understanding plant systems, visualizing and quantifying root plasticity at relevant scales poses technical challenges. Excavating the root crown from the soil (&#34;shovelomics&#34;6) is a common method, but fine roots exploit small pores between soil aggregates, and excavation inevitably leads to some degree of loss of these fragile roots. Furthermore, destructive harvest makes it impossible to follow changes in one root system over time. In situ imaging methods such as X-ray computed tomography allow direct visualization of roots and soil resources at high spatial resolution7, but are expensive and require specialized equipment. Hydroponic experiments avoid constraints associated with extracting roots from soil, but root morphology and architecture differ in aqueous media as compared to the mechanical constraints and biophysical complexity of soils8,9. Finally, rhizosphere processes and functions cannot be integrated with developmental plasticity in these artificial media.
We present a protocol for the construction and use of rhizoboxes (narrow, clear-sided rectangular containers) as a low-cost, customizable method to characterize root growth in soil over time. Specially designed frames encourage roots to grow preferentially against the back&#160;panel due to gravitropism, increasing the accuracy of root length measurements. Rhizoboxes are commonly used to study root growth and rhizosphere interactions10,11,12, but the method presented here offers an advantage in simplicity with its single-compartment design and inexpensive materials, and is designed to study root responses to localized nutrients. However, the method could also be adapted to study a range of other root and rhizosphere processes such as intra/interspecies competition, spatial distribution of chemical compounds, microbes, or enzyme activity. Here, we investigate genotypic differences among maize hybrids in response to patches of 15N-labeled legume residue and highlight representative results to validate the rhizobox method.

<table border="0" cellpadding="0" cellspacing="0" width="863">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1.27 cm diameter PVC pipe</td>
			<td style="width:123px;">JM Eagle</td>
			<td style="width:119px;">530048</td>
			<td style="width:407px;">305 cm per box, cut into lengths as specified in the protocol</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PVC side elbows</td>
			<td style="width:123px;">Lasco</td>
			<td>315498</td>
			<td>2 per box</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PVC 90-degree elbows</td>
			<td style="width:123px;">Charlotte</td>
			<td style="width:119px;">PVC 02300 0600</td>
			<td>4 per box</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PVC T joints</td>
			<td style="width:123px;">Charlotte</td>
			<td style="width:119px;">PVC 02402 0600</td>
			<td>4 per box</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Extruded acrylic panes</td>
			<td style="width:123px;">TAP Plastics</td>
			<td style="width:119px;">N/A</td>
			<td>2 per box, 0.64 cm thick x 40.5 cm wide x 61 cm long</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HDPE spacers (sides)</td>
			<td style="width:123px;">TAP Plastics</td>
			<td style="width:119px;">N/A</td>
			<td>2 per box, 0.64 cm thick x 2.5 cm wide x 57 cm long</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HDPE spacers (bottom)</td>
			<td style="width:123px;">TAP Plastics</td>
			<td style="width:119px;">N/A</td>
			<td>1 per box, 0.64 cm thick x 2.5 cm wide x 40.5 cm long</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HDPE spacers (patch)</td>
			<td style="width:123px;">TAP Plastics</td>
			<td style="width:119px;">N/A</td>
			<td>2 per box, 0.64 cm thick x 3.8 cm wide x 28 cm long</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polyester batting</td>
			<td style="width:123px;">Fairfield</td>
			<td>#A-X90</td>
			<td>2.5 cm x 40.5 cm strip per box</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">20-thread screws</td>
			<td style="width:123px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td>3.2 cm long, 0.64 cm diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Washers</td>
			<td style="width:123px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td>0.64 cm internal diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hex nuts</td>
			<td style="width:123px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td>sized to fit the screws</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Light deprivation fabric</td>
			<td style="width:123px;">Americover, Inc.</td>
			<td>Bold 8WB26.5</td>
			<td>1 piece 95 cm wide and 69 cm long per box</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sand</td>
			<td style="width:123px;">Quikrete</td>
			<td>No. 1113</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Field soil</td>
			<td style="width:123px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Transparencies for tracing</td>
			<td style="width:123px;">FXN</td>
			<td>FXNT1319100S</td>
			<td>One per side of the box to be traced</td>
		</tr>
	</tbody>
</table>

an optimized rhizobox protocol to visualize root growth and responsiveness to localized nutrients

Roots are notoriously difficult to study. Soil is both a visual and mechanical barrier, making it difficult to track roots in situ without destructive harvest or expensive equipment. We present a customizable and affordable rhizobox method that allows the non-destructive visualization of root growth over time and is particularly well-suited to studying root plasticity in response to localized resource patches. The method was validated by assessing maize genotypic variation in plasticity responses to patches containing 15N-labeled legume residue. Methods are described to obtain representative developmental measurements over time, measure root length density in resource-containing and control patches, calculate root growth rates, and determine 15N recovery by plant roots and shoots. Advantages, caveats, and potential future applications of the method are also discussed. Although care must be taken to ensure that experimental conditions do not bias root growth data, the rhizobox protocol presented here yields reliable results if carried out with sufficient attention to detail.

Roots grew preferentially against the back of the box, as anticipated. Total traced root length on the back of the box ranged from 400 to 1,956 cm, as compared to 93-758 cm on the front of the box. Pairwise Pearson correlation coefficients were calculated between scanned root length and traced root length on the front of the box, back of the box, and the sum of front and back was used to determine whether tracing accurately reflected total root length (n = 23, as the plant in one box died...

Watch this Scientific Journal Video about An Optimized Rhizobox Protocol to Visualize Root Growth and Responsiveness to Localized Nutrients at JoVE.com

An Optimized Rhizobox Protocol to Visualize Root Growth and Responsiveness to Localized Nutrients

Visualizing and measuring root growth in situ is extremely challenging. We present a customizable rhizobox method to track root development and proliferation over time in response to nutrient enrichment. This method is used to analyze maize genotypic differences in root plasticity in response to an organic nitrogen source.

Roots are notoriously difficult to study. Soil is both a visual and mechanical barrier, making it difficult to track roots in situ without destructive ...

This method can help answer key questions in the field of Root and Rhizosphere Science, such as how roots respond to localized patches of nutrients. The main advantages of this technique are that it allows repeated, non-invasive measurements of a single root system in soil, but it doesn't require specialized equipment and it's relatively inexpensive. Gather the parts for the Rhizobox for assembly.These include front and back panels made of clear acrylic about 40 centimeters by 61 centimeters. At this point, there are side and bottom spacers on top of the back panel. The spacers are aligned with previously drilled holes in the panels.Cut a length of polyester padding to go along the bottom of the Rhizobox. Lay the padding on the back panel directly above the bottom spacer to help prevent leaking. Put the top panel in position on the spacers to hold the padding in place.Now get hardware to assemble the Rhizobox. Use a screw, two washers, and hex nut for each of the drilled holes. Place a washer on the front panel and tighten the screw through it to the back panel.Another washer and the hex nut. To avoid soil loss, ensure that all of the screws are very tight. Also, create two spacers to form the treatment and control patches.Make them with high density polyethylene sheets and secure a screw at the top to allow only partial insertion. For light deprivation and heat reduction, prepare a protective case that can enclose the box. Finally, build a frame to encourage roots to grow against the back panel.This PVC frame holds the box at an angle of approximately 55 degrees. Have ready a homogenized mixture of field soil and sand. Begin with a large bag containing the substrate mixture for each Rhizobox.Label two small ziptop bags per box for the treatment and control patches. Use a scale and weigh 30 grams of the soil sand substrate. Transfer the substrate into the control bag.In the same way, add 30 grams of substrate to the treatment bag. Then weigh one gram of nitrogen 15 labeled nitrogen source and add it to the treatment bag. Mix the substrate and nitrogen source thoroughly.Work with one Rhizobox and it's patch spacers. Insert the two spacers into the Rhizobox until the screw prevents further motion. Mark the depth of the bottom edge of the spacers on the side of the Rhizobox.Then remove the spacers for the next steps. Using a funnel, fill the Rhizobox from the large bag of substrate to the marked depth. Move the funnel back and forth slowly and evenly to fill the Rhizobox uniformly.When the substrate is at the marked depth, put the spacers into the box. They should be five centimeters from the left and right sides of the box. Continue filling the box until the substrate is about five centimeters from the top of the box.Next, arrange for slow irrigation of the substrate in the box with 150 milliliters of water with drip emitters or by hand. Let it rest several hours or overnight so that the water diffuses and the area around each spacer is thoroughly wet. At this point, remove the spacers to leave an empty cavity for the patches.Now, tape transparency film to the outside of the box. Use the transparency to label one patch as treatment and the other as control. Then use the funnel and the prepared control substrate to fill the control patch.This is the labeled control patch after it has been filled. Move on to fill the treatment patch with the prepared treatment substrate in the same manner. When done, use a permanent marker to trace the boundary of each patch on the transparency film.Next, fill the Rhizobox evenly with the remaining substrate from the large bag. Finish by tracing the top of the substrate on the transparency. Once the box is ready, transplant a germinated seed.First, use a narrow spatula to dig a hole at the center of the Rhizobox. The hole should be 2.5 centimeters deep. Place the germinated seed inside ensuring the radical is oriented directly downward.Trace the location of the seed on the transparency attached to the box. Cover the seed, then water it with up to 50 milliliters of deionized water. Next, enclose the box in its case to prevent light from interacting with the roots during growth.Take the box to the frame prepared for it. Place the Rhizobox on the frame to encourage growth toward the back frame. Retrieve the box after every three to four days of plant growth.With the case removed, trace the plants visible roots by using a different color pen each time. As in this example, be consistent and systematic for this step. Return the covered box to its stand and ensuring it is in its original orientation.Here, the total root lengths of the traced roots on the back of 24 Rhizoboxes are plotted against root lengths measured using a scanner and computer software. A similar plot for traced root patterns at the front of the box demonstrates the roots grew preferentially against the back of the box. The consistent slopes in this plot of the logarithm of the total root length as a function of days of growth suggests the growth rates were similar between the different boxes.Here are data for root length density for one maize genotype. The density for the control patch is smaller than the density for the nitrogen treated patch. The experiment compared root length density for six separate maize genotypes.In all cases, the root length density was greater in the nitrogen 15 labeled treatment patch versus the control patch. This protocol can be combined with other methods such as sphygmography or florescence in situ hybridization in order to visualize the spacial distribution of enzyme activity or microbes.

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