Hydroponics and Plant Growth Study Guide Flashcards

Vocabulary flashcards covering light, photosynthesis fundamentals, light spectrums, hydroponic system types, and light-nutrient interactions.

Photosynthesis

Process where plants convert light energy into chemical energy (glucose)

Photosynthesis Equation

$$6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$$

Law of Limiting Factors

Key principle stating that when one factor is limiting, increasing the other factors will not help much to increase photosynthetic rate

Daily Light Integral (DLI)

Total amount of photosynthetically active radiation (PAR) received per day, measured in $mol \cdot m^{-2} \cdot day^{-1}$

Photosynthetically Active Radiation (PAR)

Light wavelengths between $400\,nm$ and $700\,nm$ used in photosynthesis

Dilution Effect

Potential negative effect of increasing DLI where biomass increases faster than nutrient uptake, reducing tissue nutrient concentrations

Chlorophyll a

Photosynthetic pigment that strongly absorbs blue (~$430\,nm$) and red (~$662\,nm$) light

Chlorophyll b

Photosynthetic pigment that absorbs blue (~$455\,nm$) and red (~$642\,nm$) light

Carotenoids

Photosynthetic pigments that absorb blue and green wavelengths and protect plants from excess light

Red Light

Light in the spectrum of $660\text{--}700\,nm$ that drives photosynthesis effectively and promotes stem elongation and flowering initiation

Blue Light

Light in the spectrum of $400\text{--}500\,nm$ that regulates growth form, promotes compact growth, controls stomatal opening, enhances leaf expansion, and improves chlorophyll content

Green Light

Light in the spectrum of $500\text{--}600\,nm$ that penetrates deeper into thick canopies to support shaded lower leaves

Optimal Light Combination

Mixed light spectrum containing $70\text{--}80\%$ red and $20\text{--}30\%$ blue light

Hydroponics

Growing plants in nutrient-rich water solutions without soil

Electrical Conductivity (EC)

Hydroponic solution parameter that measures total dissolved salts and nutrients

Hydroponic pH Range

Optimal range usually between $5.5$ and $6.5$ for optimal nutrient uptake

Deep Water Culture (DWC)

Hydroponic system where plant roots are suspended directly in oxygenated nutrient solution supplied by air pumps and air stones

Kratky Method

Passive Deep Water Culture hydroponic method requiring no pumps or electricity, where an air gap forms as plants consume water to provide oxygen

Ebb and Flow

Hydroponic system (also known as Flood & Drain) that periodically floods growing beds with nutrients using a timer-controlled pump

Nutrient Film Technique (NFT)

Hydroponic system where a continuous thin film of nutrient solution flows past roots along a slight slope

Wick System

Passive hydroponic system using wicks to draw nutrients from a reservoir into a growing medium holding moisture around roots

Aeroponics

Hydroponic system where roots are suspended in air and sprayed with a fine mist of nutrients for maximum oxygen exposure

Transpiration-Dependent Nutrients

Nutrients such as Calcium ($\text{Ca}$) and Boron ($\text{B}$) that move slowly in xylem and whose concentrations increase with higher DLI and transpiration

Active Uptake Nutrients

Nutrients such as Potassium ($\text{K}$) and Manganese ($\text{Mn}$) that are actively transported and may decrease in concentration under high light due to the dilution effect

Transpiration

Water loss from plant leaves that creates an upward flow in xylem