Abstract
Detailed knowledge of the distribution of roots in the soil is important in understanding the extraction of water and nutrients from soil. Various techniques have been developed to monitor root-length density under field conditions. Excavation techniques, including soil cores, have long been considered to give reliable estimates of root-length density, but these techniques are laborious in sample collection and tedious in determination of root lengths. An attractive alternative for monitoring root-length density has been the minirhizotron whereby a periscope is inserted into a clear tube permanently installed in the soil for repeated and rapid measures of root development. The objective of this study was to compare the ability of the minirhizotron technique to measure root-length density as compared to the root-core technique.
As in previous studies, substantial disagreement existed between the two techniques in the top 30-cm of the soil. The results from the minirhizotron consistently indicated a much lower root population than the root-core technique in the surface layer of soil. This is especially worrisome because more than 45% of the root-length density was found in this layer with the root-core technique. At deeper soil layers, the minirhizotron data proved to be no less variable than the root-core technique making the determination of statistically significant results difficult. Finally, the relationship between the minirhizotron and soil-core results varied with time even when the observations from the soil surface layer were ignored. Attempts to directly translate minirhizotron observations into a root-length density using a correlation approach would be suspect based on the results of this experiment.
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References
Bohm, W, Maduakor, H and Taylor, H M 1977 Comparison of five methods for characterizing soybean rooting density and development. Agron. J. 69, 415–419.
Bragg, P L, Govi, G and Cannell, R Q 1983 A comparison of methods, including angled and vertical minirhizotrons, for studying root growth and distribution in a spring oat crop. Plant and Soil 73, 435–440.
Brown, D A and Upchurch, D R 1987 Minirhizotron: A summary of methods and instruments in current use. In Minirhizotron Observation Tubes: Methods and Applications for Measuring Rhizosphere Dynamics. Spec. Pub. 50. Ed. H M Taylor. pp 15–30. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI, USA
Glenn, D M, Brown, M W and Takeda, F 1987 Statistical analysis of root count data from minirhizotrons. In Minirhizotron Observation Tubes: Methods and Applications for Measuring Rhizosphere Dynamics. Spec. Pub. 50. Ed. H M Taylor. pp 81–87 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI, USA.
Gregory, P J 1979 A periscope method for observing root growth and distribution in field soil. J. Exp. Bot. 30, 205–214.
Levan, M A, Ycas, J W and Hummel, J W 1987 Light leaf effects on near-surface soybean rooting observed with minirhizotrons. In Minirhizotron Observation Tubes: Methods and Applications for Measuring Rhizosphere Dynamics. Spec. Pub. 50. Ed. H M Taylor. pp 89–98. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI, USA.
Merrill, S D, Doering, E J and Reichman, G A 1987 Application of a minirhizotron with flexible, pressurized walls to a study of corn root growth. In Minirhizotron Observation Tubes: Methods and Applications for Measuring Rhizosphere Dynamics. Spec. Pub. 50. Ed. H M Taylor. pp 131–143. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI USA.
Newman, E I 1966 A method of estimating the total length of root in a sample. J. Appl. Ecol. 3, 139–145.
Parker, C J, Carr, M K V, Jarvis, N J, Puplampu, B O and Lee, V H 1991 An evaluation of the minirhizotron technique for estimating root distribution in potatoes. J. Agric. Sci. 116, 341–350.
Sanders, J L and Brown, D A 1978 A new fiber optic for measuring root growth of soybeans under field conditions. Agron. J. 70, 1073–1076.
Smucker, A J M, Srivastava, A K and McBurney, S L 1982 Quantitative separation of roots from compacted soil profiles by the hydropneumatic elutriation system. Agron. J. 74, 500–503.
Sokal, R R and Rohlf, F J 1981 Biometry. W H Freeman and Co., New York. pp 402–412.
Tennant, D 1975 A test of a modified line intersect method of estimating root length. J. Ecol. 63, 995–1001.
Upchurch, D R 1987 Conversion of minirhizotron-root intersections to root length density. In Minirhizotron Observation Tubes: Methods and Applications for Measuring Rhizosphere Dynamics. Spec. Pub. 50. Ed. H M Taylor. pp 51–65. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI, USA.
Upchurch, D R and Ritchie, J R 1983 Root observations using video recording system in mini-rhizotrons. Agron. J. 75, 1009–1015.
Upchurch, D R and Ritchie, J R 1984 Battery-operated color video camera for root observations in mini-rhizotrons. Agron. J. 76, 1015–1017.
Vos, J and Groenwold, J 1983 Estimation of root density by observation tubes and endoscope. Plant and Soil 74, 295–300.
Vos, J and Groenwold, J 1987 The relation between root growth along observation tubes and in bulk soil. In Minirhizotron Observation Tubes: Methods and Applications for Measuring Rhizosphere Dynamics. Spec. Pub. 50. Ed. H M Taylor. pp 39–49 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI, USA.
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Samson, B.K., Sinclair, T.R. Soil core and minirhizotron comparison for the determination of root length density. Plant Soil 161, 225–232 (1994). https://doi.org/10.1007/BF00046393
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DOI: https://doi.org/10.1007/BF00046393