Date of Award

2010

Thesis Type

Masters

Document Type

Dissertation

Divisions

Faculty of Science

Department

Institute of Biological Sciences

Institution

Universiti Malaya

Abstract

This study was aimed to investigate the effects of physiological stresses such as pruning, shading, phloemic stress and plant hormones such as gibberellic acid (GA3) and naphthalene acetic acid (NAA) on the growth, development and flowering process of bougainvillea plants. The plants (Bougainvillea glabra and Bougainvillea spectabilis) were grown under prevailing conditions (temperature 21-32°C, maximum PAR 2100 μE m-2 s-1 and relative humidity of 60-90%) using completely randomized design. Field experiments as well as biochemical analysis were carried out at the Plant Physiology Garden and the Plant Physiology Laboratory, Institute of Biological Sciences, University of Malaya. Results on frequent pruning of Bougainvillea glabra plants gave the highest quantum yield, chlorophyll a and b, and maximum flower initiation per plant compared to those of nonpruning plants. Though the sugar content in pruned plants decreased, probably due to the prolonged vegetative phase, flowering process continues and developed new flower shoots. Minimum branch (14.43 gm) fresh weight and low potassium content were observed in complete pruning plants. The present study discovered that different shading treatments (2100 ± 200, 1470 ± 200, 1050 ± 200 and 525 ± 200 μE m-2 s-1) have great effects on flower initiation, longevity, leaf chlorophyll and sugar content and plant quality in Bougainvillea glabra. Light shading more than 1470 ± 200 μE m-2 s-1 has led to inhibit flower initiation completely and the high light intensity that resulted in increased sugar and chlorophyll content may be attributed to stimulation of flower initiation and in turn to the deceleration of flower abscission. The effect of GA3, phloemic stress and combined treatment of GA3 and phloemic stress on flower blooming, expansion, development and longevity in Bougainvillea spectabilis was also analyzed. The results showed that the bract size and shape were both increased by 40% ii in 100 ppm GA3. Blooming was three days earlier in 100 ppm GA3 treated plants than those in the control. Longevity of flowers was increased by four days in phloemic stress and two days in combined treatment of 100 ppm GA3 and phloemic stress than those in control. Finally, longevity was found to be almost ten days longer in NAA (100 ppm) than those in both control and GA3 treatments in Bougainvillea spectabilis. The prolonging effect of low concentrations of NAA (100 ppm) at the initial budding stages was more effective compared to its application at other stages of development and at higher concentrations (150 ppm NAA). Maximum bract weight and shoot length were observed in the GA3 and GA3 combined with NAA treated flowers. The above findings have given a better understanding of the effects of hormones and physiological stresses on the growth and development of the bougainvillea flower and its longevity. Hence, it is suggested that these physiological and hormonal stresses can be used to maintain better plant growth and flower longevity.

Initial

khm

Additional Information

Dissertation (M.A.) – Faculty of Science, Universiti Malaya, 2010.

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