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The Limit of Crop Extractable Water for Wheat in a Space Flight Application

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  024074,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.9535) @2002
Authors:   J.H. Norikane, G.K. Tynes, H.G. Levine
Keywords:   Crop extractable water, wheat, Turface, heat pulse soil moisture sensors, pressure sensor

The objective of this research is to determine the limit of crop extractable water (CEW) for wheat grown within substrate-based nutrient delivery systems designed for spaceflight applications. The substrate compartments were constructed of clear polycarbonate and were each equipped with a bottom-situated porous tube and filled with sieved 1-2 mm Turface. Seeds were germinated, transplanted into the surface of the Turface in the substrate compartment, and a sheet of plastic was used to cover the to limit evaporation from the medias surface. The compartments were irrigated with half-strength Hoaglands nutrient solution via the porous tubes. Plant transpiration was monitored using a digital scale. Soil moisture levels were also monitored using a pressure sensors mounted to the porous tubes and heat pulse soil moisture sensors were embedded in the substrate. The plants were grown for a minimum of 45 days prior to imposing drought conditions, which were maintained until weight changes in the substrate compartments decreased to a minimum. The media from the compartments was subsequently weighed, dried, and reweighed. The average limit of CEW on a weight basis was 39.7%. The experiment was replicated five times.

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