INFLUENCE OF SOIL WATER MATRIC POTENTIAL AND RESISTANCE TO PENETRATION ON CORN ROOT ELONGATION

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Abstract
A study of the interacting effects of soil bulk density and soil water matric potential on resistance to penetration and on corn root elongation showed that for any level of resistance, elongation was further restricted as potential decreased (suction increased). This was explained through the effect of matric potential on plant turgor, which in turn affects the ability of the root to overcome resistance. At negligible resistance, elongation was greater in a clay loam soil than over a range of equivalent osmotic potentials in solution, indicating that moisture transport in the soil apparently did not restrict moisture supply to the root. It is suggested that the presently accepted upper limits of resistance for corn growth may be too high.