Do Now (5 min.) Directions: Answer in complete sentences in your research journals: Which solution has a higher buffering capacity, filtered water or HRE water? Which solution has a higher buffering capacity, filtered water or HRE water? Back up your answer with an explanation. Back up your answer with an explanation. What makes a solution have more Buffering Capacity? What makes a solution have more Buffering Capacity?

HW Complete your Germination Lab report. Complete your Germination Lab report.

How does electrical conductivity relate to plant nutrition? Mr. M. Gonzalez

Objectives I can explain why organisms of the plant kingdom need nutrients. I can explain why organisms of the plant kingdom need nutrients. I can describe the relationship between elements and nutrients. I can describe the relationship between elements and nutrients. I can relate electrical conductivity to nutrients. I can relate electrical conductivity to nutrients.

Question? How can a plant perform photosynthesis? How can a plant perform photosynthesis? 0/121668/Irrigation-photosynthesis.gif

Make a list of the elements you see on this figure in your notebooks. Make a list of the elements you see on this figure in your notebooks. Use your table of elements. Use your table of elements.

Question? Why does a plant perform photosynthesis? Why does a plant perform photosynthesis?

Because it needs to make ATP - plant body energy!

You may have noticed CHNOPS. C = Carbon C = Carbon H = Hydrogen H = Hydrogen N = Nitrogen N = Nitrogen O = Oxygen O = Oxygen P = Phosphorus P = Phosphorus S = Sulfur S = Sulfur Mg = ? Mg = ? Na = Sodium Na = Sodium Cl = Chlorine Cl = Chlorine K = Potassium K = Potassium Ca = Calcium Ca = Calcium Fe = Iron Fe = Iron Cu = Copper Cu = Copper Zn = Zinc Zn = Zinc Others Others

What element is Mg. What element is Mg. Notice it makes up the heart of this molecule. Notice it makes up the heart of this molecule.

Plants also need to make the 4 organic compounds that make up their body. Which requires ATP Carbohydrates Proteins Lipids Nucleic Acids

So, how does electrical conductivity relate to this? Electrical Conductivity is a measure of the rate (how fast) at which a small electric current travels through a solution. Electrical Conductivity is a measure of the rate (how fast) at which a small electric current travels through a solution /Electricity.jpg

Molecules & Nutrients Most plant nutrients (plant food) are made of charged molecules or salts. Most plant nutrients (plant food) are made of charged molecules or salts. The more nutrients (salts) the faster the electricity will travel through the solution. The more nutrients (salts) the faster the electricity will travel through the solution.

Element + Element = Molecule When some elements come together they form charged molecules or salts. When some elements come together they form charged molecules or salts. Nutrients and plants (+ all living things) are made of molecules! Nutrients and plants (+ all living things) are made of molecules!

So, in a sense, living molecules (life) needs non- living molecules (nutrients) to keep on living.

Question What will happen to the electrical conductivity if there are a lot of nutrients (salts) in a solution? What will happen to the electrical conductivity if there are a lot of nutrients (salts) in a solution?

Answer If you send a small electrical current through a solution with a lot of nutrients the electricity will travel very fast. If you send a small electrical current through a solution with a lot of nutrients the electricity will travel very fast. This means you will get a big measurement. This means you will get a big measurement.

Measuring EC You can use the Hanna Combo Meter to measure EC. You can use the Hanna Combo Meter to measure EC. The units that measure EC are “µS” and they appear at the top right-hand portion of the screen. The units that measure EC are “µS” and they appear at the top right-hand portion of the screen. Press the set button firmly and continuously until it appears. Press the set button firmly and continuously until it appears. µSµS

Remember Conductivity is a measure of the rate at which a small electric current flows through a solution. Conductivity is a measure of the rate at which a small electric current flows through a solution. When the concentration of nutrients is high, the current will flow ________. When the concentration of nutrients is high, the current will flow ________. When the concentration of nutrients is low then the current will flow ________. When the concentration of nutrients is low then the current will flow ________.

Question Why is measuring EC important? Why is measuring EC important?

Why is measuring EC important? Measuring the EC of your solution is important because it will determine if it has enough nutrients to feed your plants. Measuring the EC of your solution is important because it will determine if it has enough nutrients to feed your plants.

3 EC Facts An EC meter shows the reading in microohms per centimeter cubed (µMho/cm 3 ) or microsiemens per centimeter cubed (µS/cm 3 ). An EC meter shows the reading in microohms per centimeter cubed (µMho/cm 3 ) or microsiemens per centimeter cubed (µS/cm 3 ). 1 µMho/cm 3 = 1 µS/cm 3 1 µMho/cm 3 = 1 µS/cm 3 High temperatures will affect the EC measurement giving. High temperatures will affect the EC measurement giving.

EC levels for most plants Fruiting Plants Leafy Plants Initial growth µS/cm µS/cm 3 Average EC 2500 µS/cm µS/cm 3 Fruiting µS/cm 3 Winter (low light) µS/cm µS/cm 3 Summer (high light) µS/cm µS/cm 3

Problems With Nutrients When a plant uses a nutrient from a chemical “salt” molecule in a nutrient solution, it is actually only using up a part of that molecule. The remaining part of that molecule generally stays in the solution and can eventually reach dangerous levels of concentration. When a plant uses a nutrient from a chemical “salt” molecule in a nutrient solution, it is actually only using up a part of that molecule. The remaining part of that molecule generally stays in the solution and can eventually reach dangerous levels of concentration. What needs to be done? What needs to be done?

Log entry (5 min.) Explain why organisms of the plant kingdom need nutrients. Explain why organisms of the plant kingdom need nutrients. Describe the relationship between elements and nutrients. Describe the relationship between elements and nutrients. Explain how electrical conductivity relates to nutrients. Explain how electrical conductivity relates to nutrients.

HW Complete your Germination Lab report. Complete your Germination Lab report.

Bibliography Nelson/Pade Multimedia (1999). Hydroponics Guide. 100+p. Nelson/Pade Multimedia (1999). Hydroponics Guide. 100+p.