偃松生长特性及球果和种子发育的形态特征研究

Study on Growth Characteristics and Morphological Changes during Cone and Seed Development of Pinus pumila

【目的】为揭示偃松生长特性及球果和种子发育特征变化,建立外部形态与内部解剖特征相对应的关系,确定最适的球果采摘时间,并为进一步提出合理的提质增效辅助措施提供理论依据。【方法】连续3年观测12株定株母树的生长特性和开花特征,采用扫描电镜观察花粉微形态,测定发育过程中的球果和种子各性状变化,石蜡切片法观察种子内部结构特征。【结果】4月中旬至5月下旬是孢子叶球分化期,6月上旬当年生球花张开,雌花轴顶端形成深红色的花芽。6月下旬到8月上旬,花芽长变幅为10.36~18.44 mm,芽宽变幅为5.57~10.79 mm。9月,当年生花芽停止生长进入越冬休眠期,第2年春季恢复生长。授粉期始于6月中旬雄球花成熟并散粉,小孢子叶球紫红色,花药黄色。扫描电镜结果显示,小孢子叶紧密排列生长在中轴上,表面多褶皱,密被绒毛。第2年5至6月下旬是偃松球果和种子的快速发育期,7—8月球果成熟,颜色由绿色转变为深褐色。石蜡切片显示,种子发育初期的胚状结构呈透明团状,后胚乳结构变得致密。成熟种子三角状卵形,外种壳坚硬、褐色,胚乳白色,出仁率49%,饱满率高达96.8%。球果和种子各性状之间均呈极显著的正相关关系。【结论】球果成熟历经2年,大致分为花芽发育期、球花张开期、授粉期、球果发育期;球果和种子形态特征变化较为一致;成熟时球果和种子饱满、出仁率高,8—9月是最适球果采摘的时期。

【Objective】This paper aims to reveal the growth characteristics and changes of the developmental characteristics of cones and seeds of Pinus pumila,establish the corresponding relationship between the external morphology and internal anatomical characteristics,determine the optimal cone picking time,thus provide theories for further proposing reasonable auxiliary measures to improve quality and efficiency.【Method】The growth characteristics and flowering characteristics of 12 fixed mother trees were observed for 3 consecutive years.The micromorphology of pollen was observed by scanning electron microscope.The changes of cones and seeds during development were determined,and the internal structure characteristics of seeds were observed by paraffin section.【Result】From mid-April to late May was the differentiation period of sporophylls.In early June,the current year's cones were opening,and the red flower buds grew at the top of the female flower.From late June to early August,the variation of flower bud length was 10.36-18.44 mm,and the bud width was 5.57-10.79 mm.In September,the flower buds of the current year stopped growing and entered the winter dormancy period,which resumed growth in the next spring.The pollination period began in mid-June when the male cones were mature and loosed powder,the microsporophylls were purple-red,and the anthers were yellow.Scanning electron microscope results showed that the microsporophytes were closely arranged on the central axis,with many folds and densely hairy on the surface.From May to late June of the second year was the period of rapid development of cones and seeds,and the fruit matures from July to August.The color changed from green to dark brown.Paraffin section showed that the embryo-like structure in the early stage of seed development was transparent and the endosperm structure became dense.Mature seeds were triangular-oval,with hard,brown outer shell and white endosperm,also with 49%kernel rate and 96.8%plump rate.There was a very significant positive correlation between the traits of cones and seeds.【Conclusion】The cones matured after 2 years,which included flower bud development period,flower opening period,pollination period,and cone development period.The morphological characteristics of cones and seeds were relatively consistent.When mature,the cones and seeds were full,and the kernel rate was high.August to September was the best time for picking cones.