Soil-Water-Plant-Atmosphere Relationships

Study Notes

Water is the main component of all living beings, including plants.
Water makes up 75-90% of plant tissue, varying by species.
Only 1% of the total water in a plant is used for photosynthesis.
5% of the total water is used for turgor and growth.
94% of the total water is lost through transpiration.
Water is important for photosynthesis, hydrolysis, turgor regulation, nutrient transport, and temperature regulation.
Water carries minerals from the soil via the roots to the rest of the plant.
Transpiration helps to regulate the plant's temperature, similar to how sweating regulates human body temperature.

Plants are anchored in the soil and surrounded by the atmosphere, necessitating an understanding of the relationships between these components.
Water is the key component that interacts between soil, plant, and atmosphere.
Transpiration is the process by which plants lose water to the atmosphere.
Plants absorb water and nutrients through their roots, forming raw sap.
Xylem transports raw sap throughout the plant to stems and leaves.
Stomata in leaves allow water to transpire.
Without transpiration, there would be no need for roots to absorb water.
Transpiration depends on air humidity, photosynthesis, and stomatal opening.
Plants decide how long to open their stomata for photosynthesis, affecting water loss.
In water scarcity, plants minimize stomatal opening to reduce transpiration.
Water is essentially pumped from the soil to the atmosphere via plants.

Water movement is caused by the potential differences between the leaf and the atmosphere.
Water flows from areas of high concentration (leaf) to low concentration (atmosphere).
Water moves from areas of higher energy to areas of lower energy; this energy is defined as water potential.
Water potential is the energy required to remove water from the system, factors include gravity, osmosis, matric potential, temperature, and pressure.
Water potential indicates the water's ability to perform work like movement.
Water potential is influenced by solute concentration (more solutes=less free energy), pressure, height, and capillary effects.
Distilled water has a water potential of zero due to the lack of solutes.

Water moves from the soil to the plant based on potential differences.
Water moves from less retained areas to more retained areas, or from higher to lower potential.
Soil has a potential of -0.04, while air has a potential of -95 so the water moves from the soil into the air creating a flow.
Water flows depending on energy differences, moving from more free areas to immobilized areas.
The tension matrix refers to the reaction in the soil with the potential.
Different soil types have different water retention capacities at the same pressure.
Clay soils retain more water than sandy soils and loamy soils.
Water usually flows from high to low potential, except when influenced by gravity or height.
Capillary action allows water to move upwards in soil.
Water flows from pure water to water with solutes.