模拟盐胁迫对高山紫菀种子萌发及幼胚生长的影响

以高山紫菀(Aster alpinus L.)种子为试验材料,研究不同种类不同浓度盐溶液对高山紫菀种子及幼胚生长的影响。使用浓度为0.30%、0.60%、0.90%、1.20%和1.50%的NaCl、Na2SO4、MgCl2和复合盐(NaCl ∶Na2SO4=2 ∶1)溶液模拟盐胁迫,以蒸馏水作为对照,测定不同盐胁迫下高山紫菀种子萌发及幼胚生长指标。结果表明: 1) 4种盐胁迫下,浓度为0.30%的MgCl2盐胁迫的种子发芽率与ck差异不显著,其余处理的发芽率显著低于ck;所有处理的发芽势、发芽指数与ck均有显著性差异。 2)各盐胁迫处理下,胚根长均比对照显著降低;0.30%浓度NaCl盐溶液处理的胚芽长与对照无显著性差异,其余处理的胚芽长均显著低于对照;浓度大于0.60%的所有处理组的叶面积与对照比显著降低,各浓度MgCl2盐胁迫的叶面积均显著小于对照。浓度为1.50%的复合盐溶液处理的幼胚未生长。研究表明,高山紫菀种子具有一定耐盐性,胚芽、叶片对盐分的敏感程度低于胚根。高山紫菀种子对Na2SO4、NaCl、MgCl2和复合盐的耐受适宜浓度为0.40%、0.24%、0.81%和0.30%,耐受半致死浓度为1.18%、0.53%、1.45%和0.71%,耐受极限浓度为 1.69%、 1.39%、1.98%和1.40%。高山紫菀种子对4种盐耐受程度从大到小依次为:MgCl2>Na2SO4>复合盐>NaCl。

Allelopathic Potential of Some Crop Residues on the Germination and Growth of Soybean （Glycine max L,） Merrill

Allelopathic potentials of aqueous water extracts from residues of sorghum stem, maize inflorescence and rice husks on the germination of soybeans （Glycine max. L.） were investigated. The result showed that the extracts brought about a considerable inhibition in the germination of soybean seeds, reductions in the radicle and plumule lengths of soybean seedlings. Whereas, the extracts of maize inflorescence and rice husk had more inhibitory effects on the growth of soybean radicle, all the three extracts demonstrated pronounced inhibitory effects on the growth of the plumule. The retardation of soybean germination, radicle and plumule growths were concentration dependents as the degree of retardations increases with increase in the concentration of the extracts. Statistical analysis （ANOVA, P = 0.05） revealed that there were no significant differences in the germination, radicle and plumule growths at 24 and 48 h experimental time when compared to the control. However, statistical differences abound in the growth parameters at 72 and 144 h experimental time.

Early Embryo and Larval Development of Inviable Intergeneric Hybrids Derived from Crassostrea angulata and Saccostrea cucullata

To detect the intergeneric hybridization between the oyster Crassostrea angulata and Saccostrea cucullata coexisting along the southern coast of China, reciprocal crosses were conducted between the two species. Barriers for sperm recognizing, binding, penetrating the egg, and forming the pronucleus were detected by fluorescence staining. From the results, although fertilization success was observed in hybrid crosses, the overall fertilization rate was lower than that of intraspecific crosses. A large number of hybrid larvae died at 6–8 d after hatching, and those survived could not complete metamorphosis. C. angulata ♀× S. cucullata ♂ larvae had a growth rate similar to that of the maternal species, whereas S. cucullata ♀× C. angulata ♂ larvae grew the slowest among all crosses. Molecular genetics analysis revealed that hybrid progeny were amphimixis hybrids. This study demonstrated that hybrid embryos generated by crossing C. angulata and S. cucullata could develop normally to the larval state, but could not complete metamorphosis and then develop to the spat stage. Thus, there is a post-reproductive isolation between C. angulata and S. cucullata.