遮荫对牡丹光合特性及观赏品质的影响

于2008～2011年对牡丹栽培品种进行了不同程度的长期遮荫处理(100%、65%、45%及15%自然光强),并对其中5个品种(‘傲阳’、‘粉中冠’、‘蓝宝石’、‘迎日红’及‘朱光墨润’)进行了光合特性及观赏品质的测定。结果表明:牡丹各品种光饱和点及光补偿点较高,遮荫处理下光饱和点与光补偿点有不同程度降低。65%光照下,所有品种的净光合速率较对照明显提高,成花率高,花朵直径明显增大;45%光照下,各品种成花率高,‘傲阳’、‘蓝宝石’、‘迎日红’及‘朱光墨润’4个品种的净光合速率较对照明显提高,‘粉中冠’、‘蓝宝石’、‘迎日红’及‘朱光墨润’的花朵直径较对照不同程度增大;15%光照下,所有品种的净光合速率及成花率较对照显著降低,花朵直径显著减小。‘蓝宝石’在不同程度遮荫下花色较对照没有明显变化,‘傲阳’在轻中度遮荫下花色较对照没有明显变化;‘粉中冠’及‘迎日红’在65%光照下花色变深变红,45%光照下花色开始变浅;‘朱光墨润’在45%光照下花色开始变蓝变红。研究发现,牡丹是阳生植物,但光照生态幅较宽,适度遮荫能促进光合作用,成花率高,花朵直径增大,花色鲜艳,提高观赏品质,但不同色系品种的适宜遮荫程度各异。

Effect of Shading Treatment on Photosynthetic Characteristics and Flower Quality of Paeonia suffruticosa

The effects of different shading treatments(100%,65%,45% and 15% of full sunlight) on the photosynthetic characteristics were examined with five cultivars of Paeonia suffruticosa during the period from 2008 to 2011.The results indicated that the light-saturation point(LSP) and the light-compensation point(LCP) of the five cultivars of P.suffruticosa under the full sunlight were quite high.LSPs were about 1 000 μmol·m-2·s-1 and LCPs were 73～100 μmol·m-2·s-1.With the sunlight intensity reducing,the LSPs and LCPs of all cultivars decreased gradually.The net photosynthetic rates(Pn) under 65% sunlight were significantly higher than those under full sunlight.Under 45% sunlight the Pn of ’Aoyang’ and ’Zhuguangmorun’ were significantly higher than those under full sunlight,while the Pn of other three cultivars had no remarkable change.The Pn of all the cultivars under 15% sunlight were significantly lower than those under full sunlight.The flowering rates of all the cultivars were quite high under 65% and 45% sunlight and there were no difference with those under full sunlight.But under 15% sunlight they were significantly lower than those under full sunlight.The flower diameters of all the cultivars under 65% sunlight were increased and those under 15% sunlight were decreased significantly.Under 45% sunlight the flower diameters were increased at different levels except ’Aoyang’.The effects of different shading treatments on the flower color were related to the sunlight intensity and the color of the flower itself.The color of all the cultivars had no remarkable change under 65% sunlight and they even got improved for ’Fenzhongguan’ and ’Yingrihong’,but they both gradually become lighter under 45% and 15% sunlight.With the same trend the color of ’Zhuguangmorun’ became gradually lighter and blue.The color of ’Aoyang’ under 45% had no change with those under full sunlight,but become lighter under 15% sunlight.For ’Lanbaoshi’ it had no remarkably change under different shading treatments.It is indicated that P.suffruticosa is a sun plant with shade tolerance.Moderate shading can improve its photosynthesis and the flower quality but strong shading makes them worse.