Soil Moisture

For seedlings, water is the most important substance taken up by roots; water affects root growth and function directly and other factors (such as seedling nutrition, root aeration, mechanical impedance, and soil temperature) indirectly.   Consequently, the initial survival and growth of seedlings depends on the establishment and maintenance of functional connections throughout the soil-plant-atmosphere continuum.  Newly planted seedlings can exploit the moisture in only a small volume of soil.  An imbalance in soil water relations results in slower growth and has the following effects:

• A shortage of moisture induces seedlings to close their stomata to limit water loss, which, in        turn , limits photosynthesis.
• An excess of moisture reduces the amount of oxygen available for root development by the        creation of an anaerobic environment; it also causes the release of toxic substances by soil         microorganisms that are highly injurious to seedling root systems.