SORGHUM ROOT-GROWTH AS INFLUENCED BY SOIL PHYSICAL-PROPERTIES

Variations in the plant growth media were achieved by combining kaolinite clay (lμm esd.), silt (2-50μm esd.) and sand (100-250μm esd.) in various ratios. Peds of different sizes were separated from an Okolona clay soil and used as a growth media. A layer (3 cm thickness) of the sand, silt or clay and their combinations were intercalated between sandy loam soil material in a lucite coated cardboard carton. After 21 days the plants were harvested and analyzed for a number of growth parameters and related to the physical and micromorphology of the central control layer. Germination and emergence of sorghum seed were delayed in the finer aggregates. An increase in aggregate size increased the root elongation. An examination of thin sections showed that most of the roots in the finer aggregates were grown in interpedal regions whereas in the larger aggregates roots were found in both the intrapedal as well as interpedal regions. An increase in clay content of the central layer reduced the root growth. Silt also reduced root growth but not to the extent of the clay. Maximum root growth and penetration occurred in the mixture containing about 50 percent sand. Better root growth was observed in a sandy to sandy loam texture than clay to clay loam texture. © 1978, Taylor & Francis Group, LLC. All rights reserved.