Change in Size and Cell Number during the Development of Lateral Root Primordia in Zea mays L.

Abstract

Increase in cell number, anlage volume and length have been investigated during the overall period of lateral root primordium development in excised primaries and in attached roots of Zea mays L. Each of these aspects of anlage growth was found to increase more or less exponentially during the interval between primordium initiation and subsequent emergence as a lateral in both batches of roots. Values were then determined for cell doubling time (Td), the size of the proliferative fraction (Pf), and for anlage volume (Tv) and length (Tt) doubling times during the overall period of primordium development and at intervals during this period in both the excised and attached roots. The pattern of change which took place in Td, Tv, Tl and Pf during lateral primordium development was found to be similar in both batches of roots. However, the overall period of anlage development was shorter in the excised roots than in the attached ones. Moreover, when laterals grew out of the excised roots they did so with fewer cells than comparable laterals emerging from the attached roots.