ISHS Acta Horticulturae 779: International Symposium on Growing Media
PROSPECTS OF NON-DESTRUCTIVE ANALYSIS OF ROOT GROWTH AND GEOMETRY USING COMPUTERIZED TOMOGRAPHY (CT-X-RAY) |
| Authors: | A.-M. Pálsdóttir, B.W. Alsanius, V. Johannesson, A. Ask |
| Keywords: | helical scan, Hounsfield Units (HU), peat based growing medium, pumice, rockwool, sand |
| Abstract:
More than other agricultural production branches, horticulture offers the possibility to adapt the plant environment to the requirements of the growing plant. In order to better use that potential, it is necessary to quantify root response to treatments in terms of growth and geometry. Continuous monitoring requires a non-destructive and non-invasive technology. In this context, computerized tomography (CT) has been tested before. We used recent technology in order to discriminate solid and liquid phases in growing medium (sand, pumice, rockwool) and organic growing media (peat based growing medium). The discrimination of water and air is expressed in Hounsfield's scale. Each analysis was based on virtual slides of 2 mm of thickness at an interval of 1 mm. Analysis was in an initial phase conducted in the center of the container at a magnification of 3.3. Pixel size was approx. 0.7 mm. For defining resolution of different growing media (peat, rockwool, sand, pumice) and plain nutrient solution ten single scannings were made. Hounsfield scale density differed between plant material (-2.1 ±30 HU), wetted (with ultra pure water) growing media (peat: -428 ±387 HU, rockwool: -1 ±0 HU, sand: 405 ±581 HU, pumice: 129 ±185 HU) and plain nutrient solution (0.35 ±2.60 HU). Also, air filled pores were defined in the different substrates (-960 ±5 HU). Average densities in 20 cm2 of non-irrigated growing medium were determined to -665 ±226 HU, -898 ±29.3, 811 ±20 HU and 188 ±247 HU for peat, rockwool, sand and pumice respectively. As a result, irrigation zones after watering could be identified. | |
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