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

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 of Medicago 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 acid-tolerance.But under the condition of strong acid(pH≤3.0) seed germination and seedling growth were seriously restrained by simulated acid rain.