Abstract: Using Aucuba chinensis from Badagong Mountain National Nature Reserve as a model, the regularity of fruit and seed development were elucidated basing on monthly observation on fruit/seed length, width, color and embryonic/endosperm morphology. On this basis of observation, the relationship between morphological developmental and ecological factors including annual average temperature and rainfall were analyzed. The results showed that: (1) The total development of fruit took 13 months, which means the process from fruit abscission to falling lasted from April to next April. (2) The variation of fruit length, width and peel thickness manifested a tendency which include four stages as “slow-fast-slow-fast”, and which just like a typical double “S” shaped curve. And the most obvious development of fruit shape index appeared in stage Ⅱ, whose value varied from 2.63 to 1.57. (3) In the developmental process, fruit color kept green in the early and lasted for a long time, and then turn red very quickly, which should attribute to the rapid value decreasing of blue and green color. (4) Embryo and endosperm growth were synchronized with fruit development, and growth stage Ⅰ was the critical stage for embryonic and endosperm development, in which the embryo length/width ratio increased from 1.83 to 2.56; the endosperm developed as a cellular phenotype without a typical pasty stage. (5) At 13 months after corolla drop, about 77% of the embryos were still torpedo shaped. (6) There were significant positive correlation in fruit shape index/embryo ratio and temperature/rainfall (P<0.05), but fruit shape index was more dependent on precipitation (P<0.01) and embryo rate was more dependent on annual average temperature. Based on the above, the fruit development of A. chinensis was characterized by the obvious phenomenon of simultaneous flowering and overlapping fruiting periods. And the limitation of hydrothermal conditions was probably the main reason for the slow development of fruit and seed and the impact on seedling establishment. At the same time, most of the seed embryos were not fully differentiated when the fruits were abscised, which meant that the seed development had to undergo after-ripening, and therefore the seeds were morphologically dormant.

Key words: Aucuba chinensis, seed, morphological development, hydrothermal conditions

摘要： 为了揭示桃叶珊瑚Aucuba chinensis果实与种子发育的规律，以湖南省桑植县八大公山国家级自然保护区内的桃叶珊瑚为研究对象，对其果实与种子在发育过程中的外部形态、胚与胚乳的形态变化等进行研究，并分析形态变化与原生境的温度、降雨量等生态因子的相关性。结果表明：(1) 从4月坐果到次年4月完成自然脱落，果实发育共经历13个月，果实脱落晚于翌年雌花开放和坐果。(2) 果实长度、宽度、果皮厚度等变化均经历了“慢–快–慢–快”4个阶段，生长发育呈典型的双“S”型曲线；生长期Ⅰ阶段为果实生长的关键时期，果形指数由2.63降至1.57。(3) 果实颜色转变过程中红色值先增后稳，蓝色与绿色色值先增后降，果实变红体现为绿、蓝色值迅速下降。(4) 胚和胚乳生长与果实发育同步，生长期Ⅰ阶段仍是胚乳发育的关键时期，胚长宽比由1.83增至2.56；胚乳的发育为无明显浆状期的细胞型。(5) 花冠凋落后的第13个月，仍有约77%的胚呈鱼雷型。(6) 温度与果形指数和胚率呈显著正相关(P<0.05)；降雨量与胚率呈显著正相关，与果形指数呈极显著正相关(P<0.01)。基于以上结果，我们认为桃叶珊瑚果实发育具有明显的花果同期和果期重叠现象，水热条件的限制可能是其果实与种子发育缓慢并影响种苗建成的主要原因。同时，果实脱落时多数种胚未完成分化，这意味着其种子发育需经历后熟，具有形态休眠。

关键词: 桃叶珊瑚, 果实, 种子, 胚, 形态发育, 水热条件