文冠果不同果型种实性状的概率分布与选择

Probability distribution and selection of seed and fruit traits of different fruit types of Xanthoceras sorbifolium

文冠果是无患子科单属种,其种群野生濒危,生境破碎化严重且具有自交不亲和性。文冠果有"千花一果"之称,为提高其产量,测量了4年生文冠果实生园1 051个单株的坐果序数、坐果数、果实质量、种子质量、壳质量、平均单粒质量共6个种实性状并对各种实性状按不同果型进行了单因素方差分析和分布拟合。结果表明:不同果型之间果实质量、种子质量、壳质量、平均单粒质量4个种实性状之间差异极显著,而坐果序数和坐果数2个种实性状之间差异不显著。所有种实性状均符合威布尔分布,其中果实质量、种子质量、壳质量、坐果序数和坐果数5个种实性状均符合左偏威布尔分布,说明丰产是个"小概率"事件;平均单粒质量近似正态分布,说明实验园整体种子大小较为稳定,极大值与极小值的出现概率均比较低。基于威布尔概率分布建立了早期性状选择的模型,模型预测大桃型、倒卵型、尖柱型、凸桃型、短桃型、柱型在种子质量和平均单粒质量上选择概率均比较高,可作为丰产果型,其中大桃型为丰产的最理想果型;小柱型、小桃型和短柱型的种子质量和平均单粒质量的选择概率较低,不适合作为丰产选优果型。因此可根据该分布的特性对不同果型进行选择,为进一步的育种选优提供理论支持。

Xanthoceras sorbifolium is the only species in this genus that wild-endangered in China,which may due to self-incompatible and habitat destruction severely. The paper aims to improve the yield since it was widely known as ＂a tree of thousand flower but one fruit＂. Six phenotypes for 1 051 individual trees in four-year-old seed orchard were measured in this study,including fruit number,infructescence number with fruit setting,fruit mass,seed mass,shell mass and average single grain mass. ANOVA analysis and distribution fitting based on different fruit types were carried out in all the traits. Results showed that there were significant differences in varied fruit type seeds and fruit traits,including fruit mass,seed mass,shell mass and average single grain mass,but not in the infructescence number and fruit number.All the seed and fruit traits were in accordance with Weibull distribution,the fruit mass,seed mass,shell mass,infructescence number and fruit number were in accordance with the left partial Weibull distribution,indicating that high yield was a＂small probability＂event; the average single grain mass was similar to the normal distribution,indicating that the seed size in the whole plantation was relative stable,the frequency of maximum and minimum probability was relatively low. The model of early trait selection was established based on Weibull probability distribution,indicating that big peach type,inverted egg type,pointed pillar type,convex peach type,short peach type and pillar type were higher in seed mass and average single grain mass,which can be used as high-yield fruit type,and the big peach type was themost ideal fruit type of high yield. Small pillar type,small peach type and short pillar type selection probability in seed mass and average single-grain mass were much lower,which was not suitable as a high yield fruit selection. Hence,the characteristics of the Weibull distribution can provide support for selecting excellent fruit types and further theory support of breeding selection.