聚乙醇模拟水分胁迫对油松种子萌发影响).docVIP

聚乙二醇模拟水分胁迫对油松种子萌发的影响 摘要： 以子午岭油松种子为材料，研究了聚乙二醇（PEG)模拟水分胁迫对油松种子萌发的影响。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；种子的发芽率和发芽势随胁迫强度的增加呈现明显下降趋势。25%PEG处理的种子在试验结束后仍未能萌发，表明油松种子萌发的临界PEG值小于25%（相当于-0.90MPa的水势）。种子发芽后胚根和胚轴的生长也受到PEG模拟的分胁迫，当PEG浓度为10%时（相当于-0.20MPa水势），胚根、胚轴的长度都较短，说明油松种子的胚根、胚轴的生长对PEG模拟干旱胁迫更敏感；但胚根/胚轴的比值随PEG模拟水分胁迫的强度增加而增加，表明油松种子萌芽后对水分胁迫具有较强的适应性。由此可见，干旱胁迫影响油松种子的萌发可能是导致子午岭油松人工林天然更新较差的因素之一。 关键词: 油松种子；水分胁迫； 种子萌发；聚乙二醇 The effects of Polyethylene glycol (PEG)-simulated drought stress on Pinus tabulaeformis germination Abstract：With introduced Pinus tabulaeformis seeds as test material of ，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 25% (about-0.90Mpa water potential) could not germinate at all throughout the experiment period，suggesting that 25%PEG or -0.90Mpa water potential was the threshold for the germination of Ziwuling Pinus tabulaeformis seeds．Under 10% PEG stress (about-0.20Mpa water potential)，the lengths of radicle hypocotyl were shorter，llustrating their growth be more sensitive to PEG-simulated drought stress，while the radical/ hypocotyl ratio was increased with increasing PEG concentration，indicating that Ziwuling Pinus tabulaeformis seeds had a stronger resistance to drought stress after germination. Drought stress might to be a possible cause inhibited the natural regeneration of Ziwuling Pinus tabulaeformis forest． Key word：Pinus tabulaeformis　seed ； stress on ；seed　germination ；PEG 0 引 言 随着经济的发展和人民的生活水平的提高，环境保护问题日趋迫切，防风固沙营造绿色时代已刻不容缓。据了解我国水资源位居世界第六位，而人均占世界平均水资源的1/4，这说明干旱严重影响着我国农业、林业及人民的正常生活等各个领域[1]。众所周知，水是人类赖以生存的重要条件，又是生态系统中易受限制的生态因素之一[2]。水分是种子萌发的关键环节[3]。种子萌发是植物生长周期的转折点，也是植物适应环境变化，以保持自身繁衍的重要生理特性[3]。种子萌发及幼苗生长直接影响着植被的分布和多样性[4]。在我国西北干旱地区环境脆弱，植被种类比较单一，自我调控能力相当低[5]。在干旱胁迫条件下，植物种子在萌发和生长过程中不能