聚乙二醇模拟水分胁迫对沙地樟子松种子萌发影响研究

Effects of polyethylene glycol (PEG)-simulated drought stress on Pinus sylvestris var.mongolica seed germination on sandy land.

以引种区沙地樟子松种子为材料,观测了聚乙二醇(PEG)模拟水分胁迫对沙地樟子松种子萌发的影响.结果表明,不同浓度PEG处理胁迫对种子的萌发均有一定的延缓作用;种子的发芽率、发芽指数和发芽势随胁迫强度的增加呈现明显下降趋势.30%PEG处理的种子在试验结束后仍未能萌发,表明樟子松种子的萌发的临界PEG水分胁迫值小于30%,相当于-1.20MPa的水势.种子发芽后胚根和胚轴的生长亦受到PEG模拟水分胁迫,当PEG浓度为10%时(相当于-0.2MPa水势),胚根、胚轴的长度都较短,说明樟子松种子的胚根、胚轴的生长对PEG模拟干旱胁迫更敏感;但胚根/胚芽的比值随PEG模拟水分胁迫的强度增加而增加,表明樟子松种子萌发后对水分胁迫具有较强的适应性.由此可见,干旱胁迫影响引种区沙地樟子松种子的萌发可能是导致沙地樟子松人工林不能天然更新的因素之一.

With introduced sandy land Mongolian pine (Pinus sylvestris var.mongolica) seeds as test material,this paper studied the effects of polyethylene glycol (PEG)-simulated drought stress on their germination.The results showed that PEG could retard the germination of stressed seeds,and the germination rate,germination index,and germination potential were all decreased with increasing PEG concentration.The seeds treated with 30% PEG (about -1.20 MPa water potential) could not germinate at all throughout the experiment period,suggesting that 30% PEG or -1.20 MPa water potential was the threshold for the germination of Mongolian pine seeds.Under 10% PEG stress (about -0.20 MPa water potential),the lengths of radicle and hypocotyl were shorter,illustrating their growth be more sensitive to PEG-simulated drought stress,while the radicle / hypocotyl ratio was increased with increasing PEG concentration,indicating that Mongolian pine seeds had a stronger resistance to drought stress after germination.Drought stress might be a possible cause that inhibited the natural regeneration of Mongolian pine on sandy land.