從誘導低溫量與益收生長素施用探討荔枝花序形成與開花

Abstract

本研究使用定量即時聚合酶鏈式反應(quantitative real time polymerase chain reaction, qPCR)分別探討‘玉荷包’在控溫環境下及‘黑葉’荔枝在自然環境下LcFT、LcFLC、LcAP1、LcAP2及LcSOC1開花基因相對表達量。‘玉荷包’荔枝的試驗結果，在15/13 °C的溫度處理下，當低於門檻溫度23.42 °C的誘導溫度累積達5706.0小時，LcFT 的相對表現量達到高峰值，可觀察到花序形成。隨著相對低溫誘導時間增加，LcFT的表達量會被正向調控。在20/15 °C的溫度處理組中，誘導溫度達4861.1小時後可觀察到荔枝花序誘導成功；而25/20℃溫度處理下的‘玉荷包’荔枝，LcFT的表達量始終維持低含量，其他開花相關基因的表達則呈現波動的趨勢，且無法觀察到荔枝花序誘導及分化之情形。‘黑葉’荔枝的試驗結果，在12108 C.U.時，達到基因相對表現量的高峰值，並可觀察到花序形成。在這項研究中，可觀察到‘黑葉’及‘玉荷包’荔枝兩個品種的所需低溫誘導時數不同，若以相同的基礎溫度計算，‘黑葉’荔枝所需的低溫誘導量遠高於‘玉荷包’荔枝。本研究另進行施用益收生長素(乙烯釋放劑)對荔枝開花的試驗調查。以‘黑葉’荔枝樹作為試驗材料，在荔枝花序抽長至10~15公分、荔枝花序小花膨大、第一朵小花綻放及小花完全綻放四個不同花序生長階段：處理濃度50及100 mg·L-1的益收生長素，持續進行三年。由三年的試驗研究結果得知，在花序小花膨大階段施用50 mg·L-1益收生長素可以增加荔枝整體的總花數和偏雌花數量，唯試驗處理組和對照組的初期結果數並沒有顯著差異，顯示益收生長素的應用雖能影響花數，但在結果產量上仍需其他協助才能有效提升。

In this study, to clear the gene relative expression of ‘Yu-Her-Pau’ and ‘Hey-Yeh’ litchi under temperature effect and natural environment we analyzed LcFT, LcFLC, LcAP1, LcAP2, and LcSOC1 gene expression through quantitative real time polymerase chain reaction (qPCR). The result of ‘Yu-Her-Pau’ showed that under 15/13 °C treatment the relative expression of LcFT peaked at 5706.0 chilling units, and the litchi inflorescence formed. While the inducing hours increased, the expression of LcFT up-regulated；under 20/15 °C treatment, litchi flower induction succeed after 4861.1 chilling units. As for litchi under 25/20 °C treatment, the expression of LcFT was keeping in a low content and the other genes expressions varied, with no litchi floral bud differentiation observed. The result of ‘Hey-Yeh’ showed that the relative expression of LcFT peaked at 12108 chilling units, and the litchi inflorescence formed. In this study, the requirement of chilling units was different in these two cultivars of litchi, and in ‘Hey-Yeh’ litchi, the requirement was much higher than in ‘Yu-Her-Pau’. Beside of the effect of temperature, we conducted experiments of plant growth regulator. ‘Hey-Yeh’ litchi trees were treated with ethephon under 50 and 100 mg·L-1 and four inflorescence stages, the length of inflorenscence is 10-15 cm, the floret swollen, the first floret blossom, and the male flowers fully blossom. In this three-year experiments, 50 mg·L-1 ethephon application in the stage of the floret swollen could increase the number of total flower and the hermaphrodite female flower of litchi. There was no significant difference of the preliminary fruit number in treatments and control group, which meant the application of ethephon could affect the flower numbers, but still need other studies to efficiently improve the fruit production.