Environmental Factors Functions of Water Environmental Factors

What important part does water play in our society? Question? What important part does water play in our society? What important part does water play in plant growth and sustainability?

Function of Water Water covers 3/4th of the earth’s surface. It is a major component of plants and animals. An exchange of water between earth and its atmosphere is a major result of evaporation and condensation, which is vital to plants and animals. This process is called the Hydrological cycle.

Hydrological Cycle: http://www.youtube.com/watch?v=hehXEYkDq_Y&feature=related Click

Function of Water All living organisms must feed so they can have energy to grow and remain healthy. Plant are no exception! Plants are made of three things: Carbon Hydrogen Oxygen 90% of plants are mostly made of water. Plants need a great deal of water to produce energy and remain healthy.

Important Role of Water Water plays an important role in all plant functions. Water is necessary for plants to remain turgor, which gives the plant rigidity and shape. Without turgor, cells could not expand and grow. Turgor: Condition in which a plant in fully expanded or filled with moisture. Water Aids in cell division and growth Helps with root development and absorption of minerals and nutrients. Provides the food in a soluble form. Helps molecules split in photosynthesis – releasing oxygen and hydrogen. Dissolves minerals in the soil so the roots can absorb the water with minerals and transport them throughout the plant. The process is called translocation.

Important Role of Water Translocation: The movement of water, minerals and nutrients upward through the plant. This occurs due to root pressure and transpiration – when water is lost by the leaves. Root Pressure pushes the water and minerals up through the xylem. Sugars move down the phloem, due to source-sink relationship Source –to Sink Relationship: When the sugars (source) are done being manufactured, they are stored in the roots, referring to the (sink).

Important Role of Water Water and mineral absorption is the major internal process. Roots are the primary source – mostly the root hairs Can also occur through the leaves – process known as foliar absorption Absorption occurs through two processes; Active absorption: The taking of up of nutrients Passive absorption: Occurs by osmosis and is the main way water is absorbed .

Important Role of Water Osmosis: Movement of water across a membrane Diffusion: Movement of molecules from a high concentration to a low concentration

Important Role of Water Transpiration: Water loss in the plant due to evaporation from plant cells Occurs primarily in the stomata Is a function of the environment Temperature , wind, etc.. Evapotranspiration: Water that is transpired from the plants and evaporated from the soil. This helps stabilize the temperature in the plant

Transpiration Stream The flow of water from the roots to the leaves via the xylem vessels that is caused by transpiration Soil Root hairs Roots Xylem Leaves Air

Important Role of Water Understanding these five processes -Photosynthesis, Respiration, Translocation, Absorption, and Transpiration can help you better understand how they are all related and crucial to plants growth.

“How Much Water is Available for Agriculture” Activity: LAB SHEET “How Much Water is Available for Agriculture”

Shortage or Excess of Water How Plants Respond to Water? Shortage or Excess of Water

What would occur if plants had an inadequate amount of water supply? Question? What would happen if the plants had an over abundance source of water supply? What would occur if plants had an inadequate amount of water supply?

Shortage or Excess of Water Plant health and development depends on water. If the main source that makes up 90% of its source is limited or supplied in an over abundance, the plant will not be able to adequately achieve its crop yield. Plants are not the same and do not all require the same amount of water to survive. There are many factors that allow plants to tolerate shortage or excess amounts of water. Deep, well-developed root system Waxy leaf surface Shiny or light colored leaves

Shortage or Excess of Water The Effects of Water Shortage: Cause plant stress More susceptible to diseases and insects Slow downs photosynthesis Wilting: The loss of water pressure in the plant, causing limpness of the plant tissue Death of the plant

Shortage or Excess of Water The Effects of Excess of Water: Cause plant stress Reduce oxygen levels for plant and root growth High soluble salt accumulation Death of plant

“Are Plant Needy for Water?” ACTIVITY LAB SHEET “Are Plant Needy for Water?”

Efficient Use of Water The amount of water required depends on several factors: The type of crop Stage of the plant The season of the year The soil or growing medium The method of fertilization being used Watering may be reduced if the weather is cloudy Proper methods eliminate buildup of high levels of soluble salts.

Efficient Use of Water Fertilizers Type of soil Season Fertilizer Stage of growth Type of plant