Plant root systems have a characteristic morphology that is modified by the edaphic conditions in which they grow. Soil texture, moisture, temperature, and depth of penetrable soil all modify root morphology. Genetic characteristics of the plant control the basic root morphological characteristics.
Zobel, R. W.
"Research Notes : Midwest soybean rhizobotanical survey,"
Soybean Genetics Newsletter: Vol. 10
, Article 31.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol10/iss1/31