The Effect of Abiotic Factor on Seed Germination

Light

• For successful germination, some seeds require light, and others require darkness. Other seeds are non-specific, and germinate in either light or dark conditions. Lettuce, petunia and impatiens are very fine seeds that need light to germinate. Covering them with soil inhibits or prevents them from sprouting. Some herb seeds, including chives, thyme and basil, may germinate in either light or dark conditions. Most large seeds need dark conditions to germinate. Not only do corn seeds need darkness before they will sprout, but they will also dry out too quickly if not covered with soil after sowing.

Water

• Water is an important abiotic factor in seed germination. For a seed to germinate, sufficient water and oxygen must be present to facilitate respiration and generate energy. Too much water, however, is as harmful as too little water. Seeds need moist, not soggy, conditions to sprout. If they are waterlogged, they are at risk of rotting; if they are too dry, they are at risk of desiccating. Seed mortality is the result of either extreme.

Temperature

• Soil temperature, not air temperature, is the abiotic factor to which botanists refer in most discussions of seed germination. Corn seeds, for example, require sowing after soil temperatures have warmed sufficiently in spring or early summer. Cold soil does not hinder the absorption of water into corn seeds, but it inhibits growth of roots and shoots, resulting in seed rot, stunted growth or weak seedlings.

  Chemical sensors in some seeds require a period of cold before they signal seeds to germinate. Cold stratification is accomplished by sowing seeds outside in autumn or chilling them in the refrigerator before sowing outside.

Wind

• An often overlooked abiotic contributor, wind can aid or hinder seed germination. Strong winds dry soggy soils quickly to prevent seeds from rotting. In the absence of enough rainfall or supplemental irrigation, wind accelerates seed desiccation, leading to possible seed mortality. Seeds downwind of pesticide applications are at risk of phytotoxicity. They absorb chemicals from sprays or dusts that leach into the soil after settling on the ground. Entire crop failures can result from inordinate amounts of pesticide drift.