Root growth of corn seedlings as affected by soil resistance to penetration

The soil resistance to penetration is affected by soil texture, compaction and moisture content. In this paper, the effects of the interaction of thes e factors on corn root growth was studied. Soil materials with 22, 30, 34, 41 and 48% of clay were packed in PVC tubes 10 cm high, with 4.3 cm of inte rnal diameter to reach bulk densities of 1.07, 1.18, 1.36 and 1.53 g cm(-3) . Water was added to reach water potentials of -0.034, -0.106 and -0.640 MP a. Corn seedlings were grown in the tubes for 48 hours. When the soil bulk density was low, root growth was affected mainly by soil texture. As soil b ulk density increased, there was a decrease in the effect of soil texture o n root growth. The increase in soil strength caused a decrease in root leng th and in the number of seminal adventitious roots. The primary roots showe d a lower penetration ability when compared to seminal adventitious roots. A soil resitance of 1.3 MPa caused a 50% decrease in seminal adventitious c orn roots.