Vegetable Plant Part Relationships. II. A Quantitative Hypothesis for Shoot/Storage Root Development

Abstract

A simple quantitative formulation of the concept of the control of partitioning of assimilated carbon by the behaviour of plant components as competing sinks is developed. An equation, In s = α+γ In r—ηt, relating shoot (s) and storage root (r) d. wts, and the length of growth period (t), is constructed by considering possible fates of imported assimilates into different plant parts. The values of the equations' parameters depend on the relative sink activities of the plant parts, tissue respiration rates and initial weights of plant components. The equation closely fitted data collected from a number of carrot and beet experiments in which planting density had been varied. Estimates of shoot and storage root maintenance respiration rates, derived from the parameter η, were of the correct order of magnitude. Other sets of experimental data are also discussed in the light of predictions of the theory and possible uses and extensions of this approach to assimilate partitioning are briefly discussed.