| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 100 === 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.
|
|---|
