不同pH对光皮桦种子萌发及幼苗生长的影响

以中性溶液（pH 7.0）为对照,研究不同酸碱度（pH为3.0、3.5、4.0、4.5、5.0、5.5、6.0、6.5、7.5、8.0、8.5）溶液浸泡对光皮桦种子萌发的影响.结果表明：不同pH胁迫对光皮桦种子萌发的影响不同.酸性条件下,pH为3.0、3.5的酸溶液浸泡完全抑制了光皮桦种子的萌发,发芽率为零;pH≥4.0时,种子发芽率、发芽势、发芽指数、活力指数均与pH呈显著正相关,根长抑制指数、芽长抑制指数与pH呈显著负相关;pH为6.0时,不同酸溶液（硝酸、硫酸、盐酸）对光皮桦种子萌发的影响有一定差异,其抑制作用大小顺序为：硝酸＞硫酸＞盐酸;酸溶液胁迫还延缓了光皮桦种子的萌发进程.碱性条件下,pH为7.5 ～8.5的碱性溶液胁迫对光皮桦种子的萌发影响较小,其发芽率、发芽势、发芽指数、活力指数波动范围分别为48.33％ ～ 56.67％、35.33％～38.33％、60.758 ～ 68.521、83.871～92.745;随着pH的增大,种子各项指标总体呈下降趋势.

Effect of pH Value on Seed Germination and Seedling Growth of Betula luminifera

Taking neutral solution （pH 7.0） as control,the effect of solution acidity on germination of Betula luminifera seeds was studied by soaking the seeds separately in solutions with 11 pH value gradients （pH 3.0,3.5,4.0,4.5,5.0,5.5,6.0,6.5,7.5,8.0,8.5）.The results showed that the seed germination of B.luminifera varied under different pH stress.Under pH 3.0 and pH 3.5 acid condition,the B.luminifera seed germination was completely inhibited,with no germination was observed.When pH values was ≥4.0,the germination rate,germination potential,germination index and seed vitality index were all significantly and positively correlated with the increasing acidity levels; while the root length inhibition index and bud length inhibition index values were significantly and negatively correlated with the increasing acidity level.When the pH value was equal to 6.0,different acid solution （HNO3,H2SO4,HCl） stress laid different influence on the seed germination,whose inhibition intensity was ordered as HNO3 〉 H2SO4 〉 HCl.In addition,the germination process of B.luminifera seeds was slowed down by acid stress.The seed germination was not significantly influenced under pH 7.5-8.5 alkaline condition,the germination rate,germination potential,germination index and vitality index value of B.luminifera seeds fluctuated within 48.33%-56.67%,35.33%-38.33%,60.758-68.521 and 83.871-92.745 individually.