Respiration

Respiration

1. affected by

   • commodity
   • time/maturity
   • temperature
   • CO2 and O2 conc
   • tissue damage

2. ripening is start of breakdown

   • browning is when O2 gets in

3. respiration hastens senescence

   • resp rate is lower in mature tubers
     • Pringle et al 1997

4. produces energy

5. biochemical process

   • releases ATP

6. occurs in mitochondria

   • photosynthesis occurs in chlorophyll (within chloroplast)

7. sugar + O2 = CO2 + H2O + heat

8. measuring

   • volume of CO2 produced
   • volume of CO2 consumed
   • ml CO2/kg/hr
   • heat produced
     • watts/tonne
       • W/t

9. Carbohydrate sources

   • growing
     • photosynthesis
   • harvested
     • stored supply
       • finite
         • can be exhausted

10. resp rates increase

    • From storage organs...
      • to fruit...
        • to green veg...
          • to flowers.
    • high = perishable
    • low = durable

11. climacteric

    • rise in resp to peak
      • steady rise over weeks or rapid rise in days
      • associated with ripening
        • generally affects fruits that ripen after harvest
          • ethylene interactions

12. different strategy for each crop

13. resp is a chain of reactions

    • rate doubles for every 10c rise in temp
      • both low and high temp = damage
      • up to a point
      • storage temp affects tuber resp rate

14. remove field heat

    • quickly/uniformly
      • optimise storage temp