A model of the extension and branching of a seminal root of Barley, and its use in studying relations between root dimensions I. The model

Abstract

Previous papers have reported that relations between the total number, length, surface area, and volume of graminaceous root members tend to remain roughly constant during vegetative growth. Through the use of a model of the extension and branching of a seminal root of barley (Hordeum vulgare L.), which was developed for the purpose, an attempt has now been made to determine the properties of root growth responsible for the phenomenon. The present paper introduces the study and describes the model. The model takes advantage of the fact that the extension and branching of cereal root members grown in homogeneous media proceeds at approximately constant rates for lengthy periods. The overall dimensions of roots can therefore be determined by reference to formulae representing time and a limited number of properties of each type of root member. The validity of the model for the use intended is demonstrated by testing the underlying assumptions and checking the model against actual data. Other possible roles for the model are suggested. Part II of the series (Hackett and Rose 1972) reports the results and inferences from manipulation of the model. © 1972 CSIRO.