Effects of soil bulk density on the growth of maize root system under different water condition

Split root experiments were conducted on maize under both low (-0.86 MPa) and high (-0.17 MPa) soil matric potential conditions,in which seminal roots were divided equally between two compartments in partitioned galvanized steel containers containing Lou soil.Four types of soil treatments were imposed:low density (both compartments packed to 1.20 g·cm -3 ),middle density (both compartments packed to 1.33 g·cm -3 ),high density (both compartments packed to 1.45 g·cm -3 ),and mix density (one compartment packed to 1.20 g·cm -3 ,the other to 1.45 g·cm -3 ).The results showed that high soil bulk density and low matric potential effects on root growth was independently significant,but low matric potential effects was more profound,and there was also an interactive negative effect of them upon the growth.There was a significant decrease in root length and also in root dry matter when plants are grown on compacted soils or the soil matric potential reach -0.86 MPa from -0.17 MPa.In high bulk density soils,not only was there a reduction of root length but there was increase in the diameter of roots.In contrast,when plants were grown in soil of mixed bulk density,there was enhanced growth of root in low density soil to compensate or even overcompensate for reduced growth in high density soil.