Pacific Northwest Research Station

Title: The possible roles of nutrient deprivation and auxin repression in apical control

Author: Cline, Morris G.; Bhave, Neela; Harrington, Constance A.

Date: 2009

Source: Trees DOI: 10.1007/s00468-008-0294-8

Description: 

 

Apical control is the suppression of growth in lower branches by a higher dominant branch or leader shoot. We investigated possible mechanisms involved in this developmental response in three widely diverse species (Japanese morning glory, Ipomoea nil, hybrid poplar, Populus trichocarpa, x P. deltoides, and Douglas-fir, Pseudotsuga menziesii). The following two hypotheses were tested: (1) the mineral nutrient-deprivation hypothesis, which is that the continued growth of the lower branches is repressed by the diversion of nutrients to the upper dominating branch or shoot, and (2) the auxin-repression hypothesis, which is that auxin produced in the upper dominating branch or shoot moves down to the lower branches where continued growth is repressed. Overall, the data supported a significant role for nutrient availability but not for auxin repression in apical control of morning glory and poplar. In Douglas-fir, apical control in first-flushing lateral branches from over-wintered buds was largely insensitive to both nutrient availability and auxin repression; however, second flushing was sensitive to both.

Keywords: apical control, branching, lateral buds, nutrients, auxin

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Citation

Cline, Morris G.; Bhave, Neela; Harrington, Constance A.  2009.  The possible roles of nutrient deprivation and auxin repression in apical control.   Trees DOI: 10.1007/s00468-008-0294-8.