| 摘要： 台灣地區鳳梨產業為達全年可生產果實之目的，常在秋末冬初進行人工催花以調節產期，台灣地區冬季偶有低於10℃以下的低溫出現，本研究目的在探討‘台農17號’鳳梨催花後不同發育階段低溫處理後對於植株及果實的影響。 利用低溫（日溫12℃、夜溫3℃）3~5天，處理催花後不同發育階段的‘台農17號’鳳梨植株。植株於低溫處理下，夜間淨光合作用在、氣孔導度與淨二氧化碳交換量皆很低，僅在明期與暗期轉換時，因溫度的升高而有一波峰出現。植株在回溫後第二天，其淨光合作用、氣孔導度與淨二氧化碳交換量回復。催花後6、12及17天，植株經低溫處理後，葉綠素螢光參數Fo在低溫處理後會明顯上升；Fv/Fm、Fv/Fo與葉綠素含量則會下降，尤其在葉片寒害徵狀處葉綠素螢光參數與葉綠素含量近乎0，且葉片綠色部分的離子滲漏率會高於對照組。在光合產物方面，低溫處理後，葉片的可滴定酸會明顯高於對照組。葉片綠色部分的可溶性糖含量在低溫處理後明顯低於對照組，白色與莖頂部份兩處理無明顯差異，但於催花後葉片白色部分的可溶性糖含量會漸漸上升，而莖頂部份則漸漸下降。澱粉於各部位低溫處理後皆無明顯差異，但於莖頂澱粉含量在催花後會明顯上升。於低溫處理後，葉片綠色部分的乙烯釋放量與呼吸率皆高於對照組；莖頂部份的乙烯釋放量與呼吸率在催花後會明顯下降。 在植株大量及微量元素方面，在大量元素部分，低溫處理後葉片綠色及白色部分的鉀含量會略低於對照組，白色部份的鎂含量在低溫處理後會高於對照組，在葉片白色部分的全碳含量與碳氮比會明顯低於對照組低，其餘元素在低溫處理後皆無明顯差異。植株開花後葉片綠色部分的碳、氮、鈣與錳的含量會比未開花株高，而鉀與鐵在開花株中的含量比未開花株低；葉片白色部份，開花株中除了錳之外其餘含量皆較未開花株低；莖頂部份，開花株碳、鈣與錳含量較未開花株高，而磷、鐵、鋅與銅含量較未開花株低。 低溫處理後，電顯及切片觀察對於生長點細胞並未造成明顯外觀傷害，但對於葉片及開花結果情形有較大的影響。催花後第0天與第6天處理低溫後開花率最低，且果實果重及果目數最少，隨花芽發育漸成熟，對於低溫的傷害越小，但在果實外觀上出現木栓化的情形。低溫處理後的植株其果實轉色較慢，果肉顏色較白，全可溶性糖與澱粉含量也較低。大量元素方面各處理間無明顯差異，鋅在對照組中有較高含量，錳在對照組中含量最低。 於催花後0~17天期間，低溫處理的植株，葉片會出現許多褐斑，且光合產物下降，開花率明顯偏低，嚴重者導致植株死亡，果實大小、外觀及品質也會受到嚴重的影響。In order to produce pineapple fruits year round in Taiwan, pineapple growers usually forced flowering in the late fall or winter to force the production of pineapple fruits by late spring or summer. The purpose of this study was to investigate the effects of low temperature upon the development of the ‘TN-17’ pineapple plants and fruits, during different time periods after forced flowering. The ‘TN-17’ pineapple plants underwent an application of forced flowering. Next they were exposed to 12℃/8H, 3℃/16H for 3-5 day periods during different stages of their development, then the they allowed to grow to maturity. At the end of 50 days, photosynthesis, stoma conduction, and Net CO2 exchange were found to be very low, but throughout the experiment, during the dark to light period, they showed a peak. On the 6th、12thand 17th days after forced flowering, chlorophyll fluorescence parameter Fo value also showed a peak. However, in browning areas caused by chill injury, Fv/Fm, Fv/Fo, chlorophyll fluorescence parameter and chlorophyll content decreased to almost 0. Additionally, the green part of leaves suffered high membrane leakage. The components of photosynthesis that were measured after cold exposure at 3℃, were titratable acid, total soluble sugar, and starch. Titratable acid was increased. Total soluble sugar in the green part of leaves decreased while in the shoot apex and the white part of the pineapple plant there was no change. On the other hand, total soluble sugar increased in the white part but decreased in the shoot apex. As for starch content, there were no significant differences between the control and low tem perperature treatment, but the total trend in the shoot apex was that the starch content rose. Ethylene production, respiration rate, and mineral content were affected by low temperature treatment. Ethylene production and respiration rate showed no significant differences in the control, the white part, and the shoot apex, but increased slightly in the green part. However, the total trend of ethylene production and respiration rate was a decrease in the shoot apex. Minerals showed a decrease of K in the white and green part; an increase of Mg in the white part；a decrease in total carbon content and C/N; and no significant differences in all other minerals. Further results in mineral analysis were in the comparison of flowering and non-flowering plants. C、N、Ca and Mn were higher in flowering than in non-flowering. K and Fe was lower in flowering than non-flowering. Minerals in the white portion of flowering plants were lower than non-flowering except for Mn. C、Ca and Mn in the shoot apex of flowering plant were higher than non-flowering, but P、Fe、Zn and Cu were lower than the non-flowering. After low temperature treatment, there was no apparent physical injury to the shoot apex, but injury symptoms did show up in the resulting leaves and fruits. Those plants that were exposed to low temperature between 0-6th day after forced flowering showed the lowest flowering rate. The resulting number of fruitlets and fruit weight were also lower than at any other stages. Exposure to cold during the inflorescent stage damaged the young plants but resulted in higher cold tolerance in the maturing plants and fruits. However, there was some phellem-like growth on the skin of the fruit. After low temperature treatment, the color turning rate of the peel and pulp were slowly than the control. The total soluble sugar and starch was also lower, Zn content was lower, but the Mn content was higher. There were no significant differences in other minerals. In conclusion, forced flowering and low temperature treatments resulted in the following: browning spots on the green part of leaves, decreased flowering rate, increased titratable acid, decreased total soluble sugar, and plant death in cases of serious cold injury. Low temperature had a serious affect on fruit weight, fruit appearance, and fruit quality. |
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