紫花地丁花形态的季节转化对繁育系统及结实的影响

Effect of seasonal transformation of flower morphology on reproduction of Viola philippica

紫花地丁是一种观赏性状优良的园林草本种质资源。本研究以紫花地丁为研究对象,观测并分析不同花形态对花期物候、花部特征和繁育系统的影响。结果表明:1)紫花地丁具有两种不同形态的花,春季花为开放花,有彩色花冠且花瓣5枚,花萼5枚;花期在4月中到下旬,花期较短,表现为集中开花模式。生于夏秋季的花无花瓣,花萼包裹雌雄蕊,为闭锁花;花期在5月初到9月初,表现为持续开花模式。2)开放花每单花平均有花粉粒7053个,P/O值为173.32~204.49。闭锁花每单花平均花粉粒179.2个,P/O值为4.46~5.95。结合杂交指数表明开放花的繁育系统为异交,部分亲和,需传粉者,而闭锁花为严格的闭花受精。3)开放花花柱具膝曲结构,下方2枚雄蕊背基部有明显的蜜腺体并伸入花瓣形成的距。蜂类传粉者通过碰撞花柱挤压柱头,推动雄蕊距状下臂做杠杆运动进行传粉,从而促进药隔附属物裂开。闭锁花属于严格的闭花受精,不需要传粉媒介。4)闭锁花的单株结实率及结籽率显著高于开放花。

Viola philippica is a garden plant with excellent ornamental characteristics,and there are large germplasm resources for this species.V.philippica forms different types of flowers during the growing season.The objective of this study was to determine how this variable florescence phenology affects the breeding system.V.philippica produces two kinds of flowers.In spring,it forms chasmogamous flowers with five petals and five calyxes.These flowers are produced in a mass-flowering pattern in a short period from mid-to late April.The flowers produced in summer and autumn are cleistogamous.They have no petals,and the sepals wrap the female parts and stamens.The cleistogamous flowers are produced in an extended flowering pattern from early May to the beginning of September.The average number of pollen grains per chasmogamous flower was 7053,and the pollen/ovule ratio(P/O)was 173.32-204.49.There were 179.2 pollen grains per cleistogamous flower,and the P/O value was 4.46-5.95.The results show that the breeding system of open flowers is heterozygous,partially compatible,and pollinated,while the closed flowers are fertilized.The style of chasmogamous flowers has a curved structure,and nectaries at the base of the dorsal part of the lower two stamens extend to the base of the petals.Bee pollinators press the stigma by colliding with the style,pushing the stamen arm in a lever motion to pollinate,thus promoting the separation of the appendages.The cleistogamous flowers show strict closed fertilization and do not require pollination.The seed setting rate and seed setting rate per individual plant are significantly higher for plants with cleistogamous flowers than for plants with chasmogamous flowers.