澳大利亚无患子科种子中物理休眠的发生：对9个属14个物种的调查
Occurrence of physical dormancy in seeds of Australian Sapindaceae: a survey of 14 species in nine genera.
作者信息
Cook A, Turner S R, Baskin J M, Baskin C C, Steadman K J, Dixon K W
机构信息
School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley, WA 6009, Australia.
出版信息
Ann Bot. 2008 Jun;101(9):1349-62. doi: 10.1093/aob/mcn043. Epub 2008 Mar 27.
BACKGROUND AND AIMS
Sapindaceae is one of 16 angiosperm families whose seeds have physical dormancy (PY). However, the extent and nature of PY within this family is poorly known. The primary aims of this study were: (1) to evaluate seed characteristics and determine presence (or not) of PY within nine genera of Australian Sapindaceae; and (2) to compare the frequency of PY across the phylogenetic tree within Australian Sapindaceae.
METHODS
Viability, imbibition and seed characteristics were assessed for 14 taxa from nine genera of Sapindaceae. For five species of Dodonaea, optimal conditions for germination and dormancy break were evaluated. An in situ burial experiment was performed on D. hackettiana seeds to identify the factor(s) responsible for overcoming PY. Classes of dormancy and of non-dormancy for 26 genera of Sapindaceae were mapped onto a phylogenetic tree for the family.
KEY RESULTS
Mean seed viability across all taxa was 69.7 %. Embryos were fully developed and folded (seven genera) or bent (two genera); no endosperm was present. Seeds of all five Dodonaea spp. and of Distichostemon hispidulus had PY. Hot-water treatment released PY in these six species. Optimal germination temperature for seeds of the four Dodonaea spp. that germinated was 15-20 degrees C. Following 5 months burial in soil, 36.4 % of D. hackettiana seeds had lost PY and germinated by the beginning of the winter wet season (May). Laboratory and field data indicate that dormancy was broken by warm, moist temperatures (> or =50 degrees C) during summer.
CONCLUSIONS
PY occurs infrequently in genera of Sapindaceae native to Australia. Seeds of Dodonaea and Distichostemon had PY, whereas those of the other seven genera did not. Seeds of these two genera and of Diplopeltis (a previous study) are the only three of the 20 native Australian genera of Sapindaceae for which germination has been studied that have PY; all three belong to subfamily Dodonaeoideae.
背景与目的
无患子科是16个被子植物科之一，其种子具有物理休眠（PY）。然而，该科内PY的程度和性质鲜为人知。本研究的主要目的是：（1）评估澳大利亚无患子科9个属的种子特征并确定是否存在PY；（2）比较澳大利亚无患子科系统发育树中PY的频率。
方法
对无患子科9个属的14个分类群的种子活力、吸胀作用和种子特征进行了评估。对于车桑子属的5个物种，评估了发芽和打破休眠的最佳条件。对哈氏车桑子种子进行了原位埋藏实验，以确定克服PY的因素。将无患子科26个属的休眠和非休眠类别绘制到该科的系统发育树上。
主要结果
所有分类群的平均种子活力为69.7%。胚已完全发育并折叠（7个属）或弯曲（2个属）；无胚乳。车桑子属的所有5个物种以及糙毛异柱花的种子都具有PY。热水处理解除了这6个物种的PY。4个能发芽的车桑子属物种种子的最佳发芽温度为15-20摄氏度。在土壤中埋藏5个月后，36.4%的哈氏车桑子种子在冬季湿季开始时（5月）已失去PY并发芽。实验室和田间数据表明，休眠在夏季被温暖、潮湿的温度（≥50摄氏度）打破。
结论
PY在澳大利亚本土的无患子科属中不常见。车桑子属和异柱花属的种子具有PY，而其他7个属的种子没有。这两个属以及双盾无患子属（先前的一项研究）的种子是已研究发芽情况的20个澳大利亚本土无患子科属中仅有的3个具有PY的属；这3个属均属于车桑子亚科。
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