| Summary: | 碩士 === 東海大學 === 景觀學系 === 104 === Abstract
Pruning is an indispensable work to plant care management. Appropriate pruning of shrubs can improve the structure of branches and leaves and tree form, promote the tree vigor to develop evenly, and maintain the tree health. If there are plants on the head of traffic island, the plants should not be too high, the road users must have a clear sight, so as to avoid influencing the driving safety. Therefore, the shrubs planted on the island head shall be pruned periodically and cut short. However, the small height may influence subsequent growth of shrubs, and the pruning may result in few branches and leaves as a temporary poor landscape, and the length of recovery period for the good landscape of full branches and leaves varies with the germination and growth rate of plants and the pruning mode and frequency. Therefore, different plants have their appropriate pruning modes. In addition, too frequent pruning will increase the work load of maintenance management. At present, the expenses and manpower for road plant care are short, if the planted shrubs can sprout and grow rapidly after pruning, and the plant height changes slightly, the poor appearance of bald branches and leaves will occur for a short period of time, and the pruning frequency can be reduced. Therefore, the shrubs meeting such con-ditions are applicable to the island head in the road in the future. The results of this study are expected to be used in making reasonable pruning frequency criteria for common shrubs as reference for shrub selection and pruning.
Eight common ornamental shrubs are selected for this study, including Syzygium rubrum, Duranta repens, Zanthoxylum beecheyanum, Lantana camara, Stachytarpheta jamaicensis, Gardenia jasminoides, Murraya paniculata and Aglaia odorata. Experimental method was used to learn about the growth rate of branches and leaves of the 8 shrubs and the changes in plant height in the 7-month experimental period (December 20, 2014~July 20, 2015); and to discuss the effect of continuous pruning on different fre-quencies (pruning once per month, pruning once every two months) on the growth (green coverage area, plant height) of the 8 shrubs. In addition, the effect of pruning of the 8 shrubs on subsequent growth is studied.
The experimental site was the patio of Tunghai University Library, two different ini-tial pruning ranges (30, 40 cm) were used for continuous pruning, but on different fre-quencies, pruning once on the 20th day of every month, the shrubs were pruned to 30 or 40 cm of the initial plant height. In terms of pruning once every two months, the same pruning work was done in two months. In addition, the control group was free of pruning in the experimental period. The experimental nursery stocks were planted in pots, all the potted plants were provided with the same climatic environment and the same medium, irrigated once weekly, pruned in different ways, maintained in the same way. The green coverage area of plants and the plant height changes after pruning were investigated. The investigation was implemented twice monthly, the green coverage area was measured by photographing (top view), and the plant height was measured by scale.
The basic statistics of findings is implemented before the research hypotheses are validated. Only for the part free of pruning in the experimental period, the differences in the green coverage area and plant height after 7-month growth of various shrubs in dif-ferent initial plant heights (30, 40 cm) are worked out. The research hypotheses use inde-pendent sample t-test. In addition, the one-way ANOVA is used to validate the differ-ences in the green coverage area and plant height of 8 shrubs (no pruning). Only for the part free of pruning in the experimental period, the 8 shrubs in different initial plant heights (30, 40 cm) are compared, the differences in the green coverage area and plant height of the 8 shrubs after 7-month growth are worked out. If there are differences, the Scheffe test is used to work out the differences among the 8 shrubs.
The findings show that most of the 8 plants have fully spread branches and leaves from the initial pruning to the end of test. The Stachytarpheta jamaicensis and Lantana camara have the best green coverage area apparently, Murraya paniculata and Zanthox-ylum beecheyanum are worse; meaning the branches and leaves of Stachytarpheta jamaicensis and Lantana camara grow fast, whereas Murraya paniculata and Zanthoxy-lum beecheyanum grow slowly. As for the plant height, there is no significant difference between Stachytarpheta jamaicensis and Lantana camara, but they are apparently higher than the other 6 plants (Duranta repens, Syzygium rubrum, Aglaia odorata, Gardenia jasminoides, Murraya paniculata, Zanthoxylum beecheyanum). The results of this study are expected to provide technical reference for shrub pruning.
Keywords: Green coverage area, Recovery period, Shrub
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