Plant Nutrition and Transport

Plant Nutrition

Water and nutrients are needed to grow and survive and plants will produce their own carbon source (glucose) through photosynthesis Also need carbon dioxide from the air to create glucose

Has evolved mechanisms to ensure they can take up water and nutrients and can be adapted to survive under dry conditions

A large maple tree needs 800L of water per day

Plants with water vs without water

With water a plant is turgid

without water a plant is wilted

Nutrients

Roots will take up minerals, oxygen and water while carbon dioxide with leave through the roots.

Leaves will take up carbon dioxide and light, while water and oxygen leaves here

Sugar is made from carbon and light to create glucose, oxygen and water

Coniferous and Deciduous Trees

Coniferous trees has small needle-like leaves and retain needles year round as it uses less energy to maintain

Deciduous trees has broad and flat leaves, it will drop leaves seasonally so it can spend less energy in the winter

Water movement from soil to the top

Water enters through osmosis and there is Less solute concentration inside the root. Water from the soil goes to the xylem of the vascular bundle and Next step is to move water Up the plant against gravity

How do Roots take Up water

Takes up through osmosis, movement of water form low solute concentration (soil) to high concentration of solute (cell). Root hairs provide increase surface area for absorption of water and nutrients

How does water moves to the xylem

Once water enters, it can move in between cells through apoplast (outside the cell) or through the cells themselves through symplast. Once it reaches a layer of cells called endodermis, water is redirected to move via the symplast. Allows for control of water uptake. Inside the endodermis is the Casparian strip which is how water movement is regulated

Casparian strip

It doesn’t allow water movement by apoplectic route and forces to redirect the water so it moves through the symplast. It allows for the cells to not become flooded

how water moves up the xylem

Cohesion by hydrogen bonding allows for water molecules to stick to each other and Adhesion allows for water molecules to stick to the xylem cells

Water movement in the xylem

As water molecules adhere to each other through hydrogen bonding and the walls of the xyelm, it creates a column of water internally. Water can travel upwards to the leaves at a rate of 15m per hour in a large tree

Loss of water through transpiration in leaves

Water leaves the leaves through stoma, As water leaves the stoma, water moves in through the roots, Loss of a plant's water to its environment through evaporation

How water is pulled up the plant

Because of the loss of water due to transpiration, it creates a water deficit or a negative water potential inside the leaf. This causes a pull of water into the leaf from the xylem and this pulls water up the xylem from the roots, this is the main force that causes water to move up from the roots to the leaves.

As water is lost through transpiration at the leaves, water is pulled up the xylem from the roots

Stomata

It is needed to take up CO2 and release O2 during photosynthesis, it is the only way to regulate what gets in and out. When potassium and enough water are in the guard cells the stoma opens. The stomata is found in the epidermal layer of leaf cells. Guard cells of the stomata regulate the stomal opening size. Larger the opening, the more water will be lost. There will be more stomata on the underside of leaves compared to the upperside as they are not exposed to direct light and it is cool

Stomata Opening and closing

The stomata will open when there is lots of water, sunlight and enough potassium ion levels and water will flow into the guard cell

The stomata will close when there is not enough water, low sunlight and when potassium levels are low. This causes water to leave the guard cell and close

How do Xerophytes survive desert climates

• Reduced leaf size and fleshy leaves store water

• During dry seasons, plants can dry down but grow again when it rains

• Some plants close the stomata during the day, open them at night when it is cooler

• Stomata may be located deeper inside the leaf than in the epidermis

• Leaves have thick waxy cuticles to retain water

• Plants have fewer stomata

Function of phloem

• During photosynthesis, sugar is produced in the leaves that must be transported to other parts of the plant

• This requires movement from the sources (leaves to where it is needed for growth)

• Sugar is loaded into the phloem cells by sucrose transporters. This causes a high osmotic pressure which draws in water from xyelm

• This causes pressure to build up which forces the flow of sugar down the plant

• The turgor pressure causes the sugar solution to move via "bulk flow" to reach cells that need it (growing fruit, shoots, roots) the sugar is unloaded here

Maple syrup also called xylem sap

• Is the sap from maple trees that is concentrated to make maple syrup. It is boiled to concentrate it to 66-67%

• Maple syrup is taken as "xylem sap" from trees during early spring

• In the fall, sugar is transported by the phloem to the roots for the storage. In early spring, temp are above freezing during the daytime, the sap is moved up through the xylem to give energy for leaves to grow.

• Drilling hole sin the trees allows xylem sap to drip due to positive pressure flow

We wait till early spring to tap the tree, as sugar stored in the root are moving up to the leaves by the xylem as collect that sap

Mineral Nutrition of plants

The ion channels allow for nutrients to enter cells

Macronutrients: needed nitrogen, potassium, calcium, phosphorus, magnesium, sulphur

Micronutrients: iron, manganese, boron, zinc, copper, chlorine, nickel, molybdenum