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This article in AJ

  1. Vol. 71 No. 3, p. 519-522
    Received: Nov 3, 1977

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Split Root Observation System for Glass Root Dynamics Studies1

  1. W. E. Lonkerd and
  2. J. T. Ritchie2



A split root observation system was designed to provide accurate values of root lengths and water-uptake rates for use in establishing principles of estimating water uptake from field soil.

The system consists of four independent glass-bottom root observation boxes, each suspended from a load cell mounted on a support structure. The boxes have a 5° lengthwise downward slope from the plant location and contain a shallow layer of soil about 2 cm deep A plant is supported and weighed by a fifth load cell. Using a voltmeter with a 1-µv resolution, an overall system accuracy of ±2.0 g is possible for observation box weights and ±0.4 g for the plant weight. Root growth is recorded using time-lapse photography. Photographic slides are projected on a screen and root lengths are estimated using a line-intercept method.

A sorghum (Sorghum bicolor (L.) Moench) plant was used to evaluate the system. A seedling was grown in nutrient solution until eight adventitious roots had lengths at least 25 cm long. Two roots were then planted into each observation box. System performance tests illustrated how hourly, daily, and long-term data can be used to relate plant weight, leaf area, root length, and water uptake. Split root observation systems of this type provide quantitative information on how different root zone conditions of a single plant affect root growth, water uptake, and top growth.

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