LIGHT INTENSITY AS IT AFFECTS GROWTH AND BRANCHING OF THREE WOODY PLANT SPECIES (HETEROPHYLLOUS, EUONYMUS, BIFURCATION RATIO)
Abstract
The purpose of this study was to determine the effects of light intensity during the previous and current year on growth and branching of shrubs with preformed or heterophyllous growth. Containerized, one-year-old Euonymus alata (Thunb.) Siebold 'Compacta' (dwarf burning bush), with preformed growth, and Ligustrum, obtusifolium Siebold & Zucc. var. regelianum (Koehne) Rehd. (regel privet) and Viburnum x rhytidophylloides Suring. 'Willowwood' ('Willowwood' viburnum), with heterophyllous growth, were placed in field plots in 1982 under 37%, 53%, 70%, or 100% light. After one growing season, low light intensities resulted in more leaf primordia per terminal bud of Euonymus, but number of leaves per shoot the following year did not correspond to bud morphology. Concentrations of stem and root soluble sugars and starch were greatest from Euonymus grown in full sunlight. Light intensity did not influence bud morphology or concentrations of stem and root soluble sugars and starch in privet and viburnum, the heterophyllous species. After one growing season, dry weights of viburnum were greatest in 53%, 70%, and 100% light. Plant dry weight accumulation during the second growing season was strongly affected by the light intensity at which the plants were grown the previous year. Viburnums grown in full sun in 1982 had the greatest dry weights in 1983. Regardless of light intensity in 1983, privet which were shaded in 1982 produced the greatest shoot dry weights in 1983. Full sunlight during 1982 increased number of branches, branch length, and internode length of viburnums in 1983. Privet grown in 100% light during 1983 were more highly branched than shaded plants. 'Willowwood' viburnum was found to be tolerant of light intensities ranging from 53% to 100% light. Regel privet was tolerant of all light intensities used. Growth of Euonymus was not significantly affected by light intensity. Results suggest that nurserymen could vary light intensity to optimize growth and branching of young plants to produce saleable plants in a shorter time.
Degree
Ph.D.
Subject Area
Plant propagation
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