| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 95 === Summary
To understand the changes of mineral composition in Phalaenopsis amabilis var formosa during reproductive stages. Forcing treatment of Phal. amabilis var formosa was conducted in a natural-light phytotron at day/night temperature of 25/20℃ at National Taiwan University (Taipei, Taiwan.) Through periodically sampling and mineral composition analysis. Fourteen days after forcing treatment, the concentration and content of nitrogen, phosphorus, potassium, magnesium, manganese, and zinc in upper leaves remained constant or in decrease, while increased in lower leaves. 28-65 days after forcing treatment (stalk developing stage), content of nitrogen, phosphorus, potassium, magnesium, manganese, and zinc in stalks maintained increased, but the concentration was decreased. The concentration and content of potassium in stalks was highest, compared to other elements. 84-126 days after forcing treatment (bud growth to flowering period), potassium content in lower leaves significantly decreased, but increased in flowers with development; moreover, the increment was higher than stalks.
From flowers senescence to recover stage, nitrogen, content of potassium, calcium and manganese in lower leaves of Phal. amabilis var formosa were increased significantly, but concentration and content of mineral elements in roots were decreased. Sampling the treatment of stalks excision and flowers senescence at the same time. After mineral composition analysis, all organs had more content of all element in the treatment of stalks excision than flowers senescence; among all, stem and roots had the greatest increment.
To understand the effect of different nitrogen, phosphorus, and potassium concentration in fertilizer on flower quality, longevity and vegetative growth of Phal. amabilis var formosa, used different concentration of nitrogen, phosphorus, and potassium fertilization for two flowering cycles. During first flowering cycle, all treatments had no effect on days to spiking, days to bud visible or days to first flowering, neither on diameter, number and longevity of flowers. However, total leaf areas and number of newly formed leaves of plants increased as nitrogen (0, 7.1, 14.3, 21.6 mM) and potassium (0, 2.1, 4.2, 6.4 mM) concentration increased. Applied 1.4 mM phosphorus can promote total dry weight, but increasing to 2.1 mM phosphorus was decreased it, and increased percentage of leaf abscission. Increasing concentration of potassium from 0 mM to 6.4 mM increased fresh and dry weight of plant. Applied with 0 mM nitrogen treatment resulted in highest leaf abscission rate, when increasing nitrogen and potassium concentration, abscission rate was reduced. After first flowering cycle, to analysis of mineral composition of plants, a positive relation was found between nitrogen, phosphorus and potassium concentration in plant tissues and fertilizer. However, increasing potassium concentration in fertilizer, there is a decrease of calcium and magnesium in shoots.
During second flowering cycle, days to spiking, days to from spiking to bud visible, and days to from spiking to first flowering were not affected by different nitrogen, phosphorus, and potassium concentration. Phosphorus concentration level had no effect on flower diameter and size. Increasing potassium concentration can promote stalk diameter and number of flowers, but concentration of 4.2 or 6.4 mM had no significant difference. Increasing nitrogen concentration increased total fresh weight, total dry weight, total leaf areas and number of newly formed leaves.
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