A BRIEF INTRODUCTION ON PLANT NUTRITION AND HYDROPONICS

Di LiangMichigan State UniversityKellogg Biological Station

Plants need the right combination of nutrients

to live, grow and reproduce.

The major source of plant nutrition is the fixation of atmospheric CO2 into sugar. CO2 enters through the stomata.

Not sufficient?

Plants also need inorganic nutrients. Macronutrients and Micronutrients

Macronutrients

Carbon, Hydrogen, Oxygen, Nitrogen, Potassium, Calcium, Phosphorus, Magnesium and Sulfur

Each may exceed 1% dry weight of plant.

Micronutrients

Iron, Chlorine, Copper, Manganese, Zinc, Molybdenum, and Boron

Constitute from less than one, to several hundred PPM in most plants.

Functions

Functions

The Story of Boron

Leybig’s Law of the Minimum

Plants will stop growing when a single nutrient is lacking although all other nutrients are sufficient.

N deficiency

General yellowing of older leaves (bottom of plant). The rest of the plant is often light green.

Corn: “V” shape on old leaves

N deficiency

P deficiency

Leaf tips look burnt, followed by older leaves turning a dark green or reddish-purple.

P deficiency

Rice: decreased tiller number, smaller ear, less fruits

P deficiency

Citrus: thicker skin and lower quality

K deficiency

Older leaves may wilt, look scorched. Inter veinal chlorosis begins at the base, scorching inward from leaf margins.

K deficiency

Cotton: spots occurred between veins.

K deficiency

Tomato: “green back”

K deficiency

Ca deficiency

New leaves (top of plant) are distorted or irregularly shaped. Causes blossom-end rot.

Mg deficiency

Yellowing occurs between veins. “web” pattern is on old leaves.

Mg deficiency

Why hydroponics

Too much fertilizer Easy to control Straightforward

True Hoagland Solution

6 ml of 1 M potassium nitrate4 ml of 1 M calcium nitrate

1 ml of 1 M monoammonium phosphate2 ml of 1 M magnesium sulfate

1 ml of micronutrient stock solution1 to 5 ml of iron chelate stock solution

Micronutrient stock solution per liter:

2.86 g boric acid1.81 g manganese chloride - 4 hydrate

0.22 g zinc sulfate - 7 hydrate0.08 g copper sulfate - 5 hydrate

0.02 g 85% molybdic acid

Hydroponics

ml -N -P -Fe

1M KNO3 _ 5 5

1M Ca(NO3)2 _ 5 5

1M MgCl2 2 2 2

1M KH2PO4 1 _ 1

0.05M FeEDTA 1 1 _

Micronutrient 1 1 1

1M CaCl2 5 _ _

0.5M Na2SO4 5 2 2

Total 15 16 16

Roots

-N+N

Thank you!