Masters Theses

Date of Award

8-1991

Degree Type

Thesis

Degree Name

Master of Science

Major

Landscape Architecture

Major Professor

Willard T. Witte

Committee Members

Effin T. Graham, John Day, Robert M. Augé

Abstract

These experiments were designed to study the effects of alternative copper compounds in a latex paint carrier as root pruning agents on several container-grown woody ornamental plants and subsequent physiological effects on root regeneration.

Quercus acutissima, (sawtooth oak) seedlings were used to study chemical root pruning effects and subsequent root regeneration. Interior surfaces of tube trays were painted with exterior acrylic latex paint (LP) containing 0, 47, 90 or 228 g/l tribasic copper sulfate (TCS). After 15 weeks, only 0.7 roots per seedling continued growth after being deflected by the tubewall of the 90 g/l TCS treatment compared with 3.7 for the control. Fibrous roots on plug surfaces were reduced when in contact with TCS treated container walls. Height and caliper were not affected at any TCS level. Three weeks after transplanting to larger untreated containers, height and caliper were still unaffected by any TCS treatment. Time required for regeneration of new roots was not affected by TCS treatments.

Rooted, bed-grown cuttings of Viburnum tomentosum plicatum 'Mariesii' (viburnum) were used to evaluate the effects of copper hydroxide (CH) on root pruning and root regeneration. Interior walls of 3 1 containers were painted with LP containing 0, 47, 90, 185 and 260 g/l CH. Plants were grown 5 months in a pine bark medium in these containers or control (0 LP, 0 CH) containers. Fewer roots continued growth after contact with container walls in the CH treatments compared with the control treatment. There were 61, 15, 12, and 9 roots/plant in the 47, 90, 185, and 260 g/l CH treatments respectively, while 112 roots/plant continued to grow in control treatments. Elemental analysis of serial root sections showed Cu concentrations highest in root tips with concentrations rapidly decreasing proximally. After transplanting from treated containers, 100% root regeneration of selected roots occurred within 2 days in control plants; 88% in 4 days for LP only; 92% in 4 days for 47 g/l CH; 98% in 4 days for 90 g/l CH; 76% in 4 days for 185 g/l CH; and 92% in 6 days for 260 g/l CH. After 32 days plants in the 90 g/l CH treatment reached the same level of root growth as control plants. Statistical root growth curves were established for each CH treatment. Micrographs of medial longitudinal sections of root tips in the 90 g/l CH treatment showed cells were becoming disorganized in the apical meristem. Cells within the vascular cylinder and cortex were maturing quicker than those in the control treatments. At 260 g/l CH, root cap and apical meristem cells were replaced with a callus-like mass of non-organized cells. Root tips were thickened and club-like from contact with CH treated container walls.

Rooted cuttings of Euonynus alatus 'Compacta' were grown 6 months in 0.9 l containers painted with CH to determine long term effects on secondary branching of roots in contact with treated surfaces. Harvest height of the shoot portion of the plant was not affected at any CH level. Mean distance between roots decreased in copper treated plants as CH levels increased. Fresh weights (FW) and dry weights (DW) were 12% and 18% (shoots and roots) heavier in the 90 g/l CH treatment than in control plants.

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