对分布于四川阿坝的四川牡丹(Paeonia decomposita Hand. -Mazz.)的花部特征和开花动态进行了观察,并通过分析花粉活力、估算杂交指数(OCI)、控制授粉方式和观察访花昆虫对其繁育系统进行了研究。四川牡丹花部主要特征为:花色粉红色至红紫色,随开放时间延长渐变为粉白色;辐射状花冠,花瓣8 ~ 12 枚;多体雄蕊128 ~ 203枚,花丝白色,花药黄色,有雄蕊瓣化现象;柱头位于心皮顶部,黄色;边缘胎座,心皮2 ~ 7 枚,单个心皮含胚珠8 ~33 枚;开花过程中均散发花香,但随花期延长花香略有变化。该种的群体花期相对集中,为4 月中旬至5 月中旬,但不同年份间略有差异;单花花期多数为6 ~8 d,整个开花过程中花药与柱头基本处于同一平面,雄蕊先熟。从开花第1 天至第6 天,该种的花粉活力先升高后降低,其中开花第3天至第5天花粉活力较高(约80%);从开花第2 天起柱头普遍具有可授性,长达9 d,开花第5 天至第8 天柱头可授性最强;花粉具活力和柱头具可授性的重叠时间为5 d;该种的OCI 值为4,花粉/ 胚珠比(P/ O)为207 220。四川牡丹花期不分泌花蜜,花粉是传粉昆虫的惟一报酬;主要访花昆虫为蜜蜂(Apidea)、食蚜蝇(Syrphidae)和花金龟(Cetoniinae),其中前2 类昆虫可能为该种的有效传粉者,而花金龟的传粉效率较低。授粉实验结果显示:2012 年和2014 年自然授粉植株的平均结籽率最高,为23.76%;而异株异花人工授粉和同株异花人工授粉植株的平均结籽率均较低,分别为18. 33%和11. 04%。研究结果表明:四川牡丹的繁育系统属于异交,部分自交亲和,不存在无融合生殖,需要传粉者授粉。

Floral characteristics and flowering dynamic of Paeonia decomposita Hand. -Mazz. distributed in Aba of Sichuan were observed, and its breeding system was researched through pollen viability analysis, outcrossing index (OCI) estimation, pollination measure control and flower visiting insect observation. The main floral characteristics of P. decomposita are as follows: flower color from pink to reddish purple, and turning to pinkish white with prolonging of opening time; radialized corolla with 8-12 petals; 128 - 203 polyadelphous stamens with white filament and yellow anther, having petal phenomenon in stamens; yellow stigma on the top of carpel; border placenta, 2-7 carpels, 8-33 ovules per carpel; aroma spreading during flowering process and changing with prolonging of flowering period. The flowering period of populations of this species is concentrated from the middle of April to the middle of May, but varies with years. The flowering period of solitary flower mostly is 6-8 d. Anther and stigma are basically at the same plane during whole flowering process, and stamens are protandrous. From the first day to the sixth day of flowering period, pollen viability of P. decomposita increases firstly and then decreases, in which pollen viability (about 80%) is higher from the third day to the fifth day. Stigma has receptivity generally from the second day of flowering period with duration time of 9 d, and stigma receptivity is the strongest from the fifth day to the eighth day of flowering period. And overlap time of pollen with viability and stigma with receptivity is 5 d. OCI value of P. decomposita is 4, and pollen-ovule ratio (P/ O) is 207 220. P. decomposita has no nectary, pollen is the only reward for visiting insects. And the main visiting insects include Apidea, Syrphidae and Cetoniinae, in which the former two insects may be the effective pollinators, while Cetoniinae has low pollination efficiency. The result of pollination experiment shows that average of seed setting rate of natural pollination plant in 2012 and 2014 is the highest, with 23. 76%, and that of artificial xenogamy and artificial geitonogamy plants is lower, with 18. 33% and 11. 04%, respectively. It is suggested that breeding system of P. decomposita is xenogamy, part self-compatibility and no apomixes, and needs pollination by pollinators.