Hydroponic Agriculture

Controlled Environment Agriculture

Hydroponics

• Hydroponic farming is a method of growing plants in water instead of soil.

• Why Hydroponics?

– Toxic Soil – Nutrient Poor Soils – Greater Yield • Scientific Applications – Used to test how different nutrients affect a plant.

– Better control of nutrient feeding.

Germination

• When a seed starts to grow, we say it germinates. • The cotyledons store food for the baby plant inside the seed. • When the seed starts to germinate, the first thing to come out is the main root. • The skin starts to split and the tiny shoot straightens, carrying the cotyledons with it. • To grow, the seed's growing conditions usually have to be damp, warm, and dark. • A dry seed will stay dormant unless it soaks in some water. Then it will start to germinate.

Plant Nutrition

• The method of nutrition common in plants, some bacteria, and all algae is called ____________.

– photosynthesis • These organisms are called ____________.

– • The raw materials ______________combine with sunlight to produce

glucose a.k.a simple sugar.

–

autotrophs carbon dioxide & water

• The

glucose

made is used as an ______ ______ – energy source • Most ________in the air results from photosynthesis.

– oxygen

The Chemistry of Photosynthesis

• Photosynthetic Pigments are needed to “trap” light energy.

– Chlorophyll a – Beta-carotene (function not understood) • Chemical Equation for Photosynthesis – CO 2 + H 2 O light energy & chlorophyll a C 6 H 12 O 6 + H 2 O + O 2 • Light energy absorbed by the Chlorophyll a is converted to _______ __________.

– chemical energy (ATP).

• Photosynthesis in land plants occurs in the ____ – leaves.

Plant Physiology

• Roots – Anchor the plant.

– Absorb raw materials needed for growth.

• Stem – Supports the leaves.

– Contains the tissue used for transporting materials throughout the plant.

– Xylem & phloem (like arteries & veins)

Physiology Continued

• Leaf – Thin, flat which provides maximum surface area for the absorption of light.

• Epidermis – protects the inner cells.

– Cuticle – waxy coating on some leaves.

• Palisade Cells – tall cells containing chloroplasts which are filled with chlorophyll. – Autotrophic nutrition occurs in the Palisade cells.

• Spongy Layer – Loosely arranged cells separated by interconnected air spaces used for storing gases.

• Stomate – micro openings on the leaf which allow for the exchange of gases.

The Mineral Needs of Plants

• Plant growth requires more than sunlight, carbon dioxide, chlorophyll, and water.

• Many plants require mineral substances derived from the decomposition of rock.

• Hydroponics is a method of growing plants in water enriched with mineral substances.

• Ten elements are essential to plants: calcium, hydrogen, magnesium, oxygen, potassium, carbon, iron, nitrogen, phosphorus, and sulfur.

• Other “trace” elements are needed like manganese, zinc, & copper.

Movement of Minerals into Plants

• Plant cells absorb minerals in two major ways: – Simple exchange through the cell membrane (diffusion) • Reversible • Moves from high concentration to low • Happens quickly – Active transport - the movement of a substance against its concentration. • Irreversible • Happens very slowly

Advantages of Hydroponic Gardening 1.

No weeds to pull means less competition.

2. No soil borne disease.

3.

Grow more plants in a smaller space.

4.

Plants grow more rapidly and produce larger yields.

5.

Produce is higher in nutritional value than field grown crops.

6. YOU CAN GARDEN ALL YEAR!

Maintaining Greenhouse Conditions

• Temperature - Regulates germination, growth, flowering, fruiting, longevity.

- 75/65 F generally will work for most species.

• Humidity – 50-90% RH generally – Plants, wet soils and floors provide humidity.

– Mostly worry about disease promotion.

– Vent or heat or both if condensation lingers on glass past mid-morning.

– Pre-dawn venting

Continued

• Watering – Quality--test clear water before growing your first plant. Direct yourself to do it regularly for clear water and fertilizer.

– Quantity—Do not over water plants by putting on too much water at one time.

– Frequency--depends on weather, pot, soil, species, age.

– Application method--should be automated whenever possible.