Striped maple: shoot growth and bud formation related to light intensity

Abstract

Terminal shoot growth and bud formation in striped maple (Acerpensylvanicum) were followed both in vigorous and suppressed forest trees and in suppressed trees grown in the greenhouse and garden under 10 light intensities from 6 to 82% of solar radiation in the open. All buds contained (1) a pair of preformed early leaves that grew rapidly and (2) a pair of rudimentary primordia that became either bud scales in suppressed trees, after abortion of the blade, or a second pair of leaves in vigorous or released trees. The fate of the rudimentary primordia could be regulated by light intensity. They formed bud scales at 6% light or leaves at about 18% light. Maximum height growth and leaf pair formation occurred at 30–60% solar radiation in the open, although the first internode was longest under the lowest light. When leaf production stopped, bud formation was similar in vigorous and suppressed trees. The inner and outer bud scales and the pair of preformed early leaves were produced at 2- to 4-week intervals. The rudimentary primordia were not formed until after an interval of 8–12 weeks, in late summer near the end of bud formation.