| Summary: | 碩士 === 國立中興大學 === 園藝學系所 === 98 === In Taiwan, the force flower treatment of pineapple usually used calcium carbide (CaC2) solution, but it was unstable. For this reason, the object of this study was to clear the ingredients in CaC2 solution which affected flower induction and found chemicals that may be replaced CaC2 solution. Mature pineapple plants were treated with CaC2 solution, CaC2 gas (acetylene gas), ethylene gas, CaC2 solution without acetylene gas, or first treated with 1-MCP then CaC2 gas. Results showed that CaC2 solution, acetylene gas, and ethylene gas could induce plants to flower. Plants treated with 1-MCP or CaC2 solution without acetylene gas did not flower, suggesting that acetylene gas was the main ingredient in CaC2 solution which stimulated flowering. Most of the plants bloomed at 50 days after forced flowering. The nitrogen and calcium content in the green part of the leaves of flowering plants was higher than in non-flowering plants. And the ratios of total soluble sugar to total nitrogen in flowering plants were lower than in non-flowering plants. There were no significant differences in starch content and nitrogen/ calcium ratios between flowering and non-flowering plants.
Ethylene production in leaf discs was induced by treatments with CaC2 supernatant liquid, CaC2 solution without acetylene gas, or CaC2 solution on leaf discs. Results showed that CaC2 supernatant liquid could induce more ethylene production than CaC2 solution did, but ethylene production was decrease after treatment with CaC2 solution without acetylene gas, suggested that the precipitates in the CaC2 solution could affect acetylene-induced ethylene production.
The white-green and light green sections of D leaf in pineapple plants were found to produce the most ethylene. Leaf discs from these sections were examined for the ability to further produce ethylene by using chemicals and hormones. KH2PO4, 0.1mM kinetin, 0.5ppm IBA, K2HPO4, CaCl2, and Ca(NO3)2 could not induce leaf discs to produce more ethylene. However, there was obvious ethylene production by leaf discs after treatment with CuSO4, the highest ethylene production rate being from the concentration of 0.5mM CuSO4 at 25℃. But there was even more ethylene production when leaf discs were dipped in 5mM CuSO4 aqueous solution for 10 minutes. For example, the ethylene production rate for 5mM CuSO4 at 6-12 hr was 3.5 times higher than discs incubated in 0.5mM CuSO4. CuSO4 ability to produce ethylene may be stimulated by ACC synthase activity. Results also showed the leaf discs produced a large amount of ethylene after treatment with ethephon.
Leaf discs could produce ethylene after CuSO4 treatment, so CuSO4 applying to the plants then evaluated the capability of flower induction. Pineapple plants were treated with CaC2 solution, oil-coated CaC2, different concentrations of CaCl2 or CuSO4 (0.5, 1, and 2mM), and ethephon for forcing flowers. Among them, ethephon treatment was more efficienct: 85% in flowering rate. The flowering rate of CaC2 solution and oil-coated CaC2 was 21%. Other treatments did not force flowering. The nitrogen content in the white part of D leaf was decreased with the forced flowering time, from 1.45 to 0.51%; and the green part of the leaf was maintained between 1 to 1.2%; but the nitrogen content in the green part of the leaf was significantly increased after ethephon forced flowering treatment. The total soluble sugar in the green part of the leaf before flowering by ethephon treatment was lower than other treatments, but starch had no significant difference between treatments.
CuSO4 could induce considerable ethylene production from leaf discs but very little from whole plants. The reason for failure of flower induction may be due to the fact that the quantity of ethylene production was too low to induce flowering, or there was wax on the leaf surfaces which obstructed cupric ions from entering the leaf tissues and resulted in flowering failure.
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