植物生長調節劑對百香果生長及花芽形成之影響

Effect of Plant Growth Regulators on Growth and Flower Formation of Passionfruit

於常溫（日夜溫25／20°C）下生長的「台農一號」百香果植株，噴施 paclobutrazol（pp333）250ppm強烈抑制其枝條生長，尤其是縮短節間長度；paclobutrazol不但顯著提早花芽形成時間，且降低花芽形成節位。BA lOOppm並未降低花芽形成節位，但因早期（前4週）葉間期加速，故花芽形成日期提早，然效果不如paclobutrazol。Chormequat（CCC） 500ppm只在試驗早期有稍微抑制節間長度之作用，對花芽形成無作用。Ethephon（Ethrel）130ppm則明顯抑制枝條生長和花芽形成，使嫩葉黃化說落、新稍枯死。依此結果推測GA抑制百香果之花芽形成，cytokinin促進之，而乙烯也可能是抑制的角色，尤其在逆境時，低溫（日夜溫20/15°C））環境下，「台農1號」百香果扦插植株無法形成花芽，但噴施硝酸銀200PPm則可在處理後13.3天形成花芽。噴施paclobutrazol 250ppm雖也可形成花芽，但形成時間比硝酸銀處理株延遲12天，且形成之花芽不再繼續發育增大。至於GA₃ lOOppm植株及對照組則全無花芽形成。由上述結果推測低溫所產生的逆境乙烯（stress ethylene）為百香果開花抑制之主要原因。

The cutting plants of passionfruit cv. Tai-nung No.1 were grown in phytotron at day 25℃/night 20℃, foliar application with paclobutrazol 250 ppm significantly reduced vegetative growth but had very earlier flower formation and lower node number to first flower bud. BA 100 ppm application did not descend to the node number to first flower bud, but had earlier flower formation due to shorter plastochron. Chlormequat 500 ppm application had no significantly effect on vegetative growth and flower formation. Ethephon 130 ppm application severely inhibited both vegetative growth and flower formation which was similar to the status in low temperature or water stress condition. It is suggested that the gibberellin inhibits and the cytokinin promotes flower formation of passionfruit, ethylene is also an inhibitor on flower formation especially under stress conditions. Under low temperature (day 20℃/night 15℃), the cutting plants always had no flower formation. While the plants sprayed with silver nitrate 200 ppm, they formed flower buds in 13.3 days, The plants of paclobutrazol 250 ppm formed flower buds slowly in 25.4 days, and the flower buds had no advanced development. Both the GA₃ 100 ppm application and the control plants had no flower formation. It is assumed that the stress ethylene induced by low temperature is the major cause for inhibition the flower formation in passionfruit.