Effects of Light, Water Deficit and Ethephon on Growth and Flowering in Bougainvillea spp. ‘Taipei Red’

摘要 九重葛在短日、強光的環境下易開花，以人為限水或外施乙烯釋放劑ethephon可以促進其花芽形成，故欲探討在不同光週期與不同光強度下，限水處理與噴施ethephon對九重葛花芽形成之影響。 在不同的光週下，探討限水處理與37.5 mg. L-1濃度ethephon對九重葛生長與花芽形成之影響。自然光週為11小時，長日照處理為自然光週加上晚上電照4小時，共計15小時，短日照處理則給予自然光照8小時。限水處理下分為正常灌溉與全株1/3葉片下垂時再給予全株澆灌。試驗結果顯示，以自然日照處理和短日照處理可以促進花芽形成，若此兩種光照處理下加上限水或ethephon後反而會延遲花芽出現。短日照處理雖然也會提早開花，但是開花枝條數比自然光週少，花序數也較少，碳水化合物較少，使九重葛枝條養分不足以供植物生長開花。長日照處理的枝條其花芽形成天數較自然光週處理晚8天，因此長日照會延遲花芽形成。 在不同光強度下，處理不同濃度ethephon對九重葛不同成熟度枝條花芽形成之影響方面，不遮陰處理(約900μmol. m-2.s-1)、50%遮光程度(約400μmol. m-2.s-1)及75%遮光程度(約150μmol. m-2.s-1)之三種不同光強度下，依枝條頂端下第5片展開葉的CMR值將枝條區分為25以下、25-30與30以上花芽尚未出現之三種成熟度，並施用不同濃度的ethephon 0、25、37.5 與75 mg.L-1。試驗結果顯示，在不遮陰處理下，CMR值30以上的枝條以25 mg.L-1濃度ethephon處理即可促進花芽形成，CMR值25-30的枝條以37.5 mg.L-1濃度ethephon處理下其花芽可較快形成。在50%遮陰處理下，CMR值30以上的枝條以37.5 mg.L-1濃度ethephon處理下其花芽可較快形成。75%遮陰程度不適合九重葛生長與開花。 不同限水程度對九重葛生長與花芽形成之影響方面，第一次試驗在秋冬季節，分為對照組(間隔一天澆水)、全株2/3葉片下垂時澆水、全株1/3葉片下垂時澆水、土壤水份維持20%和40%共5種處理。第二次試驗在春季進行，除了對照組改為每天澆水外，並加上1.5~2.5公分表土乾燥時澆水之處理，共6種處理。兩次試驗處理皆以全株2/3葉片下垂後復水的處理可較快促進花芽形成。全株2/3葉片下垂處理之葉片內生ACC含量最高，隨著土壤水分增加，葉片內生ACC含量有下降的趨勢，因此限水可以使植株本身內生ACC含量增加，促進枝條成熟並使花芽形成。 在乙烯釋放劑對九重葛徒長枝與水平枝條花芽形成之影響方面，將九重葛枝條分為徒長枝與水平枝條，施用ethephon 25、37.5與75 mg.L-1，並在各濃度下分為一次至三次的處理，每週噴施一次。試驗結果顯示，欲促進徒長枝條花芽形成可使用37.5 mg.L-1之ethephon處理二次，而欲促進水平枝條花芽形成則可以使用25 mg.L-1處理三次或37.5 mg.L-1處理二次。 在花苞壽命方面，分別處理以複合藥劑組合與多胺類藥劑。複合藥劑組合試驗中，有0.13 mM NAA+ 0.5 mM SA、0.29 mM GA+ 0.5 mM SA、0.22 mM BA+ 0.5 mM SA、0.29 mM GA+ 0.22 mM BA+ 0.5 mM SA、0.13 mM NAA+ 0.5 mM SA+ 0.29 mM GA、0.13 mM NAA+ 0.5 mM SA + 0.22 mM BA、0.13 mM NAA+ 0.5 mM SA+ 0.29 mM GA+ 0.22 mM BA與對照組共8種處理。多胺類藥劑試驗中，植株苞片處理以1 mM 腐胺(Diamine putrescine, Put)、1 mM 亞精胺(Spermidine, Spd)與1 mM精胺(Spermine, Spm)與對照組共4種。試驗結果顯示，欲有較佳延長苞片壽命的處理可以使用0.13 mM NAA+ 0.5 mM SA+ 0.29 mM GA+ 0.22 mM BA此組合，而多胺類藥劑可使用1 mM Put藥劑處理。 故欲以限水處理促進花芽形成，可進行全株2/3葉片下垂後復水的處理，若欲以ethephon促進花芽形成，應在不遮陰環境下且枝條成熟度足夠(CMR value>25)的狀態下處理，但濃度不應過高。Abstract The flower bud formation of bougainvillea is promoted by short day, water deficit or ethephon treatment. This studies were to investigate the effects of photoperiod, light intensity, water deficit and ethephon on flower bud formation in bougainvillea ‘Taipei Red’. The effects of water deficit and 37.5 mg.L-1 ethephon on flower bud formation in bougainvillea under different photoperiods were investigated. The natural daylength was about 11 hours during experimental period, long day treatment was nature daylength plus four hours of artificial lighting at night, short day treatment was eight hours of natural daylength. The water deficit treatments were watering as 1/3 foliage drooped and normal irrigation (the control). The results showed that the natural daylength treatment and short day treatment could promote flower bud formation. However, if the two kinds of daylengths with additional treatment of watering as 1/3 foliage drooped or ethephon could inhibit flower bud formation. Although short day treatment promoted flowering earlier, the flowering branches, inflorescences per shoot and carbohydrate content of short day treatment were less than those of natural daylength treatment. The day to first flower bud formation of long day treatment was eight days later than that of natural daylength treatment. Therefore, long day treatment will delay formation of flower bud. The effects of different concentrations of ethephon, different light intensities on flower bud formation of different maturity branches in bougainvillea were investigated. Under three light intensity treatments: no shading (approximately 800 μmol. m-2.s-1), 50% shading, (approximately 400 μmol. m-2.s-1) and 80% shading (approximately 160 μmol. m-2.s-1), based on the CMR value of the 5th leaf from the top of non-flowering branches, divided into three kinds of maturity, below 25, 25-30 and above 30, which were treated with concentrations of ethephon 0, 25, 37.5 and 75 mg.L-1. The results showed that: under non-shading environment, the branches with above 30 CMR value leaf applied with 25 mg.L-1 ethephon, and the branches with 25-30 CMR value leaf applied with 37.5 mg.L-1 ethephon could promote formation of flower bud. Under 50% shading, the branches with above 30 CMR value leaf treated with 37.5 mg.L-1 ethephon could promote formation of flower bud. However, 75% shading environment had no flower bud formation even the branches with above 30 CMR value leaf. The effects of different water deficit on the growth and formation of flower bud in bougainvillea were investigated. The first experiment was conducted in fall and winter, and there were 5 treatments: control (watering every 2 days), watering as 2/3 or 1/3 foliage drooped, keeping the volume water content of media to 20% or 40%. The second experiment was conducted in spring, besides above 5 treatments (but the control watering everyday), adding the treatment of watering as 1.5-2.5 cm of topsoil was dry to this experiment, and totally 6 treatments. The results showed that treatment of watering as 2/3 foliage drooped could promote formation of flower bud earlier in both experiments. The content of endogenous ACC in the leaves of treatment of watering as 2/3 foliage drooped was highest. The higher water content of the media, the lower ACC content in plant leaves. Thus water deficit could increase the ACC content in plant, and enhancing the maturity of branches and the formation of flower bud. The effects of ethephon on formation of flower bud of water sprout and horizontal shoots were investigated. Water sprout and horizontal shoots were treated with 25, 37.5 and 75 mg.L-1 ethephon, these concentrations were applied 1, 2 or 3 times for once a week. The results showed that: for water sprout, treating with 37.5 mg.L-1 ethephon twice could promote formation of flower bud. For horizontal shoots, either treating with 25 mg.L-1 ethephon thrice or 37.5 mg.L-1 ethephon twice could promote formation of flower bud. The effects of combined chemical treatments and polyamines on longevity of bougainvillea were observed. There were 8 treatments in combined chemical treatments, 0.13 mM NAA + 0.5 mM SA, 0.29 mM GA + 0.5 mM SA, 0.22 mM BA + 0.5 mM SA, 0.29 mM GA + 0.22 mM BA + 0.5 mM SA, 0.13 mm NAA + 0.5 mM SA + 0.29 mM GA, 0.13 mM NAA + 0.5 mM SA + 0.22 mM BA, 0.13 mM NAA + 0.5 mM SA + 0.29 mM GA + 0.22 mM BA and control. There were 4 treatments in polyamines treatments, 1 mM putrescine (Diamine putrescine, Put), 1 mM spermidine (Spermidine, Spd), 1 mM spermine (Spermine and Spm) and control. The results showed that the treatment of 0.13 mM NAA + 0.5 mM SA + 0.29 mM GA + 0.22 mM BA and 1 mM Put could prolong the bracts longevity better. In conclusion, we can use water deficit or ethephon treatment to regulate flowering time in bougainvillea. The water deficit treatment, watering as 2/3 foliage drooped was recommended can promote formation of flower bud of bougainvillea. It is useful to apply ethephon to enough maturity of branches (CMR value>25) in non-shading environment, but the concentration of ethephon should ≦37.5 mg.L-1