STEP-WISE RELEASE OF ENERGY CAPTURED AND STORED IN PHOTOSYNTHESIS Respiration STEP-WISE RELEASE OF ENERGY CAPTURED AND STORED IN PHOTOSYNTHESIS

Respiration Equation Respiration can be simply thought of as the opposite of photosynthesis All living cells respire, or break-down sugars to release the energy Roots and cells that photosynthesize also Sugars oxidize to water and carbon dioxide: C6H12O6 + 6 H2O + 6 O2 ------------------ ------------------ 6 CO2 + 12 H2O + energy Similar to burning of hydrocarbons: C8H18 + O2 -------> H2O + CO2

Factors Affecting Respiration Temperature Oxygen Soil conditions Light Plant growth

Respiration and Temperature Within the range from 0 °C to 35 °C (32 ° to 95 °F) respiration rate increases 2 to 4 times for each 10 °C rise. Night temps 5 °C lower than day reduce respiration and allow more plant growth Photo of fruit in storage or in a grocers refrigerated area.

Respiration and Oxygen With other factors being equal, the rate of respiration decreases as the concentration of oxygen decreases Photo of CA filter unit

Respiration and Soil Conditions Compacted or waterlogged soils are poorly aerated This reduces respiration in roots, resulting in poor plant growth. Photo of waterlogged, wilted plant.

Respiration and Light Plants under low light have low photosynthesis rates and reduced carbohydrate available for respiration. Etiolated seedlings.

Respiration and Plant Growth As plant leaves develop their activity, photosynthesis and respiration increase to a maximum level Then decrease as leaves age Graphic showing respiration producing ATP and other energy compounds along with degradation and resynthesis of proteins and enxymes,

Respiration Summary Requires O2 and Carbon compounds (sugars, starch, fats) Evolves CO2, H2O, and Energy Occurs in light and darkness in every cell Is a function of many environmental factors