模拟酸雨对紫花苜蓿种子萌发及幼苗生理特性的影响

Effects of Simulated Acid Rain on Seed Germination and Seedling Physiological Characteristics of Medicago Sativa L.

以紫花苜蓿的种子为研究材料,研究种子在不同pH值的模拟硫酸型酸雨作用下,种子的萌发和幼苗生理特性发生的变化。实验分别测定了种子的发芽势、发芽率、发芽指数、活力指数、幼苗的鲜重、根长、芽长、叶片叶绿素含量、叶片电导率等指标。结果表明,紫花苜蓿种子的发芽势、发芽率、发芽指数、活力指数的整体变化趋势比较一致,随着模拟酸雨浓度的增大而减小。幼苗叶片的生长量的变化差异比较大,单株幼苗的平均鲜重和根长随模拟酸雨酸性的减弱而增大,单株幼苗的平均芽长则随pH值的增大而减小,幼苗芽的生长受到酸雨的抑制主要是由根的生长受到抑制引起的。幼苗叶片叶绿素含量的整体变化趋势是随着模拟酸雨pH值的升高而增大。所测幼苗叶片的相对电导率值随模拟酸雨pH值的升高而减小,与对照相比差异显著,表明幼苗叶片受到了酸雨的破坏。试验表明,紫花苜蓿种子在pH≥4.0的弱酸条件下能够正常萌发和生长,具有一定的耐酸性,但是在pH≤3.0的强酸条件下,种子的萌发和幼苗的生长受到了显著的抑制。

Using the seed of Medicago Sativa L. as material. We studied the effect of different pH simulated acid rain on the seed germination and seedling physiological characteristics ofMedicago Sativa L. The experiment tested the germination power, germination rate, germination index, vitality index, seedling fresh weight, root length, bud length, chlorophyll content of seedling leaf and permeability of plasma membrane etc targets. The results of the test indicated that the germination power, germination rate, germination index and vitality index all decreased with the simulated acid rain density increased. There were great changes among the indexes of seedling growth increment：seedling fresh weight and root length increased with simulated acid rain pH rising,while bud length decreased with simulated acid rain pH increasing. The results indicated that bud growth was restrained by simulated acid rain. And permeability of plasma membrane decreased with the acid rain pH increasing,which showed that seedling leaves were destroyed by the acid rain. With simulated acid rain pH going up, the chlorophyll content of seedling leaf enlarged. The experiment proved that the seed of Medicago Sativa L. under the condition of weak acid（pH ≥4.0） can normally sprout and growth, and has certain acidtolerance. But under the condition of strong acid（ pH ≤3.0） seed germination and seedling growth were seriously restrained by simulated acid rain.