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!