“金冠霞帔”文冠果种实性状可塑性

Phenotypic plasticity in seed and fruit of new variety “Jinguanxiapei” of Xanthoceras sorbifolium Bunge

表型可塑性是有机体适应异质环境,增强生存能力的重要机制。以文冠果新品种"金冠霞帔"为研究对象,于2016年在不同纬度以及同一纬度两种不同土壤类型3个区域4个试验地,选取无性嫁接扩繁、树体结构相近的植株,开展控制授粉与开放授粉对比实验,并通过无性嫁接植株之间的控制授粉实现了文冠果的自交。果实成熟后采收并风干,测量果实质量、果壳质量、结果数、座果率、种子粒数、种子质量、出籽率、单粒重等12个性状,筛选了3个表型可塑性指标,并以表型可塑性指数PPI进行了综合评价。结果表明:随北京、辽宁、内蒙古的纬度变化以及褐土到风沙土的生境变化,种实性状均表现出可塑性。随种植纬度的增加,植株增加对果实种子的资源性投入,果实体积变大且数量增加,果实质量、果壳质量、种子质量、种子粒数均显著增加。从相对肥沃褐土到相对贫瘠风沙土的生境变化,种实性状表现出"趋贫特化,优先后代"的响应机制,即资源相对匮乏时,植株将有限资源分配给少量果实,减少果壳资源分配,相对多的资源分配给少量种子,种子大粒化的方式适应贫瘠生境,这种"繁殖策略"支持了文冠果具有分布广泛、适应性强、抗逆性强等特性。本研究为文冠果适应与进化研究提供基础资料,并对其栽培管理和保育利用提供重要参考。

Phenotypic plasticity is an important mechanism for the adaptation of organisms to heterogeneous environments and for the enhancement of their survival ability. Trees of new variety"Jinguanxiapei"of Xanthoceras sorbifolium Bunge with similar structure were selected for this experiment in 2016,which consisted of a replicated diallel mating of controlled pollination and open pollination in four sites of three regions. Self-pollination was achieved by grafting individuals pollinated each other. Four experimental sites located in three regions of Beijing,Liaoning and Inner Mongolia,consisting of three different latitudes and two different soil types in one of the three regions. After harvesting and drying the fruits,we measured 12 traits including fruit quality,shell quality,number of fruits,fruit rate,seed number,seed quality,seed yield,and single grain weight. Three phenotypic plasticity indicators were evaluated and finally the phenotypic plasticity index( PPI) was used to estimate the plasticity of each trait. The results showed that seed and fruit traits exhibited phenotypic plasticity across different latitudes and different soil conditions. With increasing latitude,the seed and fruit traits showed a positive response by increasing resource input to the fruits and seeds,showing increases in fruit volume,fruit number,fruit mass,fruit shell mass,seed mass and seed number. With the change of habitat from cinnamon soil to aeolian sandy soil,seed and fruit traits exhibited the response mechanism of specialization for scarce resource and priority of resource allocation to progeny. When the resources are relatively scarce,plants allocate the limited resources to a small amount of fruit,reduce the allocation of fruit shell resources,and allocate more resources to a small amount of seeds,so that the seeds are bigger to adapt to the environment of aeolian sandy soil. Such a reproductive strategy makes the species has wide distribution,strong adaptability,and strong resistance. Our results provide basic data for study of adaptation and evolution and scientific reference for breeding and cultivation of X. sorbifolium.