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Ballarat sta 2021 10 key differences c3 v c4
- 1. 10 key differences between C3 and C4 turfgrasses Dr. Phil Ford Melbourne Polytechnic
- 2. C4 turfgrasses • Couch • Kikuyu • Paspalum • Buffalo • Zoysia C3 turfgrasses • Ryegrass • Tall Fescue • Fine Fescue • Bentgrass • Poa • Kentucky Bluegrass
- 4. • It took the Millenium Drought to show that C4 grasses would survive in Melbourne without any irrigation • Some people assume it’s just a 25-30% saving in water with C4 turfgrasses • And, with no water restrictions, there has been some movement back to C3 grasses • The summer performance of C4 turfgrasses is a package, with several components
- 7. 1. The C4 pathway C4 turfgrasses use 25-30% less water each day compared to C3 turfgrasses
- 8. Stomates
- 9. 2. Cell membrane function C4 cell lipids work best between 27 – 35oC C3 cell lipids, work best between 16 – 24oC (melt down above 40oC or so)
- 10. 3. C4 turfgrasses don’t suffer Heat Stress or High Temperature Kill C3 turfgrasses experience Heat Stress due to a lack of evaporative cooling when foliage temperatures exceed 32oC or so. At 42oC or so, the cells melt down (High Temperature Kill) C4 turfgrasses: tolerate foliage temps of 60oC for 10 hours, without damage
- 12. 4. C4 turfgrass roots get better as summer proceeds, C3 roots get worse
- 13. Increasing C4 root growth as summer goes on C4 ‘Spring Root Decline’ July Aug Sept Oct Nov Dec Jan Feb Mar Apr May June 30 25 20 15 10 0 C4
- 14. C3 root growth period C3 root recovery C3 ‘root dysfunction’ July Aug Sept Oct Nov Dec Jan Feb Mar Apr May June 30 25 20 15 10 0 C3
- 15. 5. Time of year when roots are weakest and the turf is most vulnerable C4 turfgrasses: Spring Root Decline C3 turfgrasses: late summer into autumn, root dysfunction
- 16. 6. C4 turfgrasses quickly resurrect from drought stress (e.g. from summer rainfall). C3 turfgrasses won’t recover from summer drought stress until late autumn.
- 19. Fine Fescue Ryegrass Bluegrass Tall Fescue Dichondra Buffalo Kikuyu Zoysia Hybrid Couch Paspalum At 10 days At 20 days 0 10 20 30 40 50 60 70 80 90 100 % Survival
- 20. 7. Most C4 turfgrasses have rhizomes Couch, Kikuyu, Zoysia and Carpet Grass have strong rhizomes (not Seashore Paspalum or Buffalo, though). C3 turfgrasses: Kentucky Blue, and to a small extent Tall Fescue and Fine Fescue, and Browntop Bent have some rhizomes. But not Ryegrass, Bentgrass.
- 21. 8. Summary of drought resistance: Water Budget C4 turfgrasses: 0 – 5 ML/Ha per summer (very flexible) C3 turfgrasses: 8 ML/Ha per summer (not negotiable)
- 22. 9. Traction and ACL injury? AFL theory: couchgrass causes ACL injury because of high rotational traction There is a greater difference between one boot and another boot, than between C4 and C3 turfgrasses
- 24. 10. Oversowing You can successfully and sustainably oversow a C4 sward with a C3 grass (e.g. Couch or Kikuyu with Perennial Rye) for better winter performance. But you can’t oversow a C3 grass with a C4 grass for better summer performance.
- 25. 10. You can oversow a C4 grass with a C3 grass, but not vice versa Winter oversowing of Couch or Kikuyu with Perennial Ryegrass is an excellent technique to improve playability and colour, and protect the underlying C4 grass. But you can’t oversow a Perennial Ryegrass field with Couch or Kikuyu to improve summer performance.
- 26. Pure couch field Late August
- 28. Pure couch, high wear, late August
- 29. Oversown, high wear, late August
- 30. There are other differences too (e.g. growth habit, salt tolerance, Poa control options, traffic tolerance etc). If people aren’t reminded of all these benefits, there will be a push to go back to C3 grasses when water is plentiful. That’s without even mentioning climate change.