紫斑牡丹种子休眠原因初探

Primary studies with Paeonia rockii seed dormancy

为探索紫斑牡丹Paeonia rockii种子休眠原因,对其种皮透性、抑制物质强度(以豌豆Pisum sativum种子为材料)和种子不同部位外植体生长等进行了研究。结果表明:种皮透性对种子吸水率和呼吸速率有一定影响;用生根前的紫斑牡丹种子胚乳、胚、种皮浸提液处理的豌豆均有部分生根率,且生根率依次增大,但上胚轴萌发率均为0;用生根及发芽后的紫斑牡丹种子种皮、胚乳处理豌豆的生根率显著高于生根前的,且均有部分上胚轴萌发,但前两者生根率及上胚轴萌发率无显著差异;完整种子、种皮置于一旁的去皮种子、去皮种子、胚(裸胚或去子叶胚)的紫斑牡丹生根率依次提高,发芽率均为0;紫斑牡丹胚及去子叶胚均需要经过低温处理后上胚轴才可以萌发。由此说明:(1)造成紫斑牡丹种子下胚轴休眠的因素是种皮的透性、种皮及胚乳中的抑制物质。(2)紫斑牡丹种子上胚轴休眠的原因在胚内部,而与种子在生根后及发芽过程中种皮及胚乳中抑制物质强度的变化无关,去除种皮、胚乳及子叶无法解除其休眠,上胚轴休眠需要经过低温过程方可解除。

To determine causes of seed dormancy with Paeonia rockii seeds, this research studied seed coat permeability, inhibiting substance strengths using peas as the material, the growth status of different explant cultures and did difference analysis. Results showed that permeability of seed coat had certain effects on water absorption and respiration intensity of seed; some of the peas placed in endosperm, embryo, and seed coat extracts with P. rockii seeds before germination, took root with rooting rates of endosperm〈embryo〈seed coat; however, none of the epicotyls germinated. Rooting rates of peas in endosperm and seed coat extracts with germinated or sprouted P. rockii seeds were higher than those with seeds that had not germinated; they all had partial epicotyls sprouting, but no differences were found between those with germinated and sprouted P. rockii seeds. Rooting rates of P. rockii increased with complete seeds 〈 peeled seeds with seed coats alongside 〈 peeled seeds〈embryos （embryos or embryos without cotyledons）; however, none sprouted. Both embryos and embryos without cotyledons required low temperature treatment before they could germinate. Thus, （l） seed coat permeability, inhibitory substances in the seed coat and endosperm were reasons for hypocotyl dormancy with P. rockii seeds; （2） changes of inhibitory substances from rooted seeds to sprouted seeds had nothing to do with epicotyl dormancy meaning reasons for epicotyl dormancy were probably inside the embryo; and （3） low temperature could release epicotyl dormancy, but removing seed coat, endosperm, or cotyledons could not.