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.