Effects of desiccation of seeds in nine species with morphophysiological dormancy on germination and embryo growth

9种形态生理休眠的种子脱水对萌发和胚胎生长的影响

Aims In species with morphophysiological seed dormancy(MPD),little is known about the effects of desiccation of imbibed seeds on embryo growth and germination.We studied seed responses to dehydration in nine species with different levels of MPD.Methods For each species,a control test was conducted by keeping seeds permanently hydrated and exposed to the optimal stratification-incubation sequenee to promote embryo growth.Simultaneously,tests were run in which seed stratification was interrupted for 1 month by desiccation at room temperature.Important Findings In Clematis vitalba and Ribes alpinum,with non deep simple MPD,desiccation affected neither embryo growth nor seed viability,but the desiccation led to a decrease of germinative ability in R.alpinum by 16%.The seeds of Narcissus pseudonarcissus subsp.munozii-garmendiae,with deep simple epicotyl MPD,tolerated desiccation in different embryo growth stages,but their germinative ability decreased slightly.The response of species with complex levels of MPD to desiccation was more variable:Delphinium fissum subsp.sordidum,with intermediate complex MPD,and Anthriscus sylvestris and Meum athamanticum,both with deep complex MPD,tolerated desiccation.In contrast,Ribes uva-crispa with nondeep complex MPD,Lonicera pyrenaica with intermediate complex MPD and Chaerophyllum aureum with deep complex MPD,had diminished germination ability by desiccation.Although seeds of the species with simple levels of MPD tolerated desiccation,those of some species with complex levels were also highly tolerant.Thus,desiccation did not induce secondary dormancy in late embryo growth stages.The desiccation tolerance of imbibed seeds of most of the nine species may show their adaptability to climate change in the Mediterranean region.

在具有形态生理种子休眠(MPD)的物种中,吸胀种子脱水对胚胎生长和萌发的影响鲜为人知。我们研究了9种不同MPD水平的种子对脱水的反应。对每个物种进行对照实验,使种子永久保持水化并暴露在最佳层积-培养顺序中以促进胚胎生长。同时也开展了室温条件下脱水中断种子层积处理1个月的实验。研究结果显示,具有非深度简单MPD的白藤铁线莲(Clematis vialba)和高山茶藨子(Ribes alpinum)的胚生长和种子活力均不受干燥影响,但干燥使高山茶藨子的萌发力下降了16%。具有深度简单上胚轴MPD的黄水仙(Narcissus pseudonarcissus)种子在不同的胚生长阶段呈现脱水耐受性,但其萌发力略有下降。具有不同MPD复杂水平的物种对脱水的反应更为多变:具有中度复杂MPD的Delphinium fissum亚种与具有深度复杂MPD的峨参(Anthriscus sylvestris)和熊根芹(Meum athamanticum),具有脱水耐受性。与之相反,具有非深度复杂MPD的鹅莓(Ribes uva-crispa)、中度复杂MPD的Lonicera pyrenaica和深度复杂MPD的Chaerophyllum aureum,脱水后萌发力下降。虽然具有MPD简单水平的种子能够具备脱水耐受性,但一些具有复杂水平MPD的种子也具有很高的耐受性。因此,脱水不诱导胚生长后期的次生休眠。9种植物中大多数的吸胀种子的脱水耐受性可能表征其对地中海地区气候变化的适应性。