Respiration…the burn of life Horticulture

Objectives Define respiration Explain the process of respiration Compare respiration to combustion Explain why plants respire Why should we care about respiration?

Define Respiration It is the controlled expenditure of an organism's energy reserves to sustain its life processes Occurs 24/7 All cells of the plant respire, not just those containing chlorophyll

Respiration Occurs in the mitochondria Exact opposite process of photosynthesis Consumes oxygen and gives off carbon dioxide

Formula Uses stored energy (E) and gives off heat Opposite of photosynthesis C6H12O + H2O + 02 = CO2 + H2O + E

Where, what? Occurs in mitochondria in both plant and animal cells Largest organelle in the cell “Powerhouses” of the cell Provide storage areas fro respiration Cell may have 2,500 mitochondria

Combustion and Respiration Burn a carbohydrate and get carbon dioxide, water, and heat C6H12O6 + heat = CO2 + H20 + heat Respiration is the exact same!!!

Differences Combustion releases ALL the energy at 1 time. Respiration is a controlled release, plants can use the E as it is released. E is released in the form of ATP

WHY do plants respire? Cell respiration E is defined as: The process breaks chemical bonds and produces heat that is used by the cells of the plant for work. E is defined as: The ability to do work

Biological Work Maintenance of life and life processes: Growth Development Repair Movement Reproduction Transportation

How it works… Respiration converts the E stored in the nutrients (carbs, proteins, starches) into ATP which is useable by the cell.

Factors affecting respiration: Temperature: As temperature increases, so does the rate of respiration. At normal temperatures, respiration increases two to four times for each 18 F rise in temperature. Oxygen: abnormally low concentrations of oxygen in an environment will result in a lower rate of respiration.

Factors affecting respiration: Soil conditions: Compacted or waterlogged soils exclude air (oxygen). Respiration in a plant's root system is inhibited under such conditions. Light: Plants grown in low light photosynthesize at a reduced rate. Therefore, the level of available carbohydrates (glucose and others) and rate of respiration are also reduced.

Growth rate and metabolic activity: Maintenance respiration provides energy for maintenance of existing cells and tissues. Growth respiration provides energy for production of new cells and tissues. age and the availability of glucose affect the rate of respiration

Respiration and Agriculture Better Crop Management Better post-harvest handling of crops Respiration=24/7, plants need to be able to photosynthesize enough to provide E for respiration during day and night. If not, no E for growth

Respiration and Ag Plants grow best with night temps 9degrees cooler than daytime. If temps are too high, respiration increases and growth is stalled Temps too cool, respiration will be too low and growth processes won’t occur

Respiration and Ag Closely tied with degradation (breakdown of tissues) in harvested crops By slowing resp. rates after harvest, growers can improve quality

Respiration and Ag Refrigeration or cooling helps slow respiration Can increase N, forces out O2, decrease respiration Think of bananas and flowers

Fermentation Anaerobic respiration (no oxygen) Glucose is converted during several steps into alcohol (ethanol) Important for making silage