Does an Increase in Levels of Acid Affect Bean Seed Germination?

Percent Hydronium

• Every naturally occurring substance on the Earth contains a number of electrically charged particles known as ions. The pH of a garden’s soil, or its percent hydronium ion, is a measure of its acidity. The more acidic the soil is, the more positively charged ions it contains. The presence of these ions can alter the chemical structure of the nutrients found in the soil. Nutrients tend to occur most abundantly in soils with a pH rage of 6.0 to 7.5; consequently, this is the range at which most plants grow best. However, a few plants, such as beans and tomatoes, have adapted to life in more acidic soils.

Germination

• Once a flowering plant has successfully reproduced, the young embryo is housed in a protective shell, known as a seed. When surrounded by warm, moist material, the seed softens and allows fluids to enter, encouraging the growth of the embryo. As the seed germinates, the young seedling pushes out of its shell and takes root in the surrounding soil.

Bean Seeds

• Bean seeds are known for being rugged and durable. They possess a thick, tough outer coat that protects the embryo within from predation, disease and the damaging affects of winter weather. This tough seed coat may be a highly effective defense mechanism, but it can make successful germination a challenge. According to studies published by the North Mason Biology Department, bean seeds germinate best in slightly acidic conditions. Acidic soils or solutions may help dissolve the seed coat, increasing the speed at which the embryo takes in fluids, which could improve germination rates.

Cultivation

• Like most acid-loving plants, beans seeds will sprout under a wide variety of conditions; however, they grow best in well-drained soils with a pH of 4.0 to 6.5. To lower the pH at the planting site, incorporate naturally acidic, organic materials, such as coffee grounds or tea leaves, into the soil. Plant seeds 2 to 3 inches apart, then thin the seedlings to 6 inches once the plants have reached 6 inches in height. Do not soak the seeds prior to planting because this can cause the coat to split, exposing the immature embryo to the elements.