Why light is more important for ultradwarf than for bent: what greenkeepers need to know

This presentation was delivered on October 21 at the Japan Turf Show in Tokyo. It explains the units of measurement for photosynthetically active radiation (PAR), then looks at data from 2014 and 2015 at Tokyo, and at Watkinsville, Georgia. The quantity of PAR is discussed in relation to how much the grass can use, and how much is actually present.

Transcript

1. Why light is more important for ultradwarf than for bent: what greenkeepers need to know Micah Woods Chief Scientist Asian Turfgrass Center www.asianturfgrass.com 21 October 2015
2. PAR, PPFD, and DLI What do these mean? ▶ PAR is photsynthetically active radiation. It is the light with wavelengths from 400 to 700 nm. ▶ PAR is measured instantaneously as a flux of photons within those wavelengths on a surface of 1 m2. ▶ Instantaneous PAR is the photosynthetic photon flux density, (PPFD). In full sun at midday in summer, the PPFD will be about 2,000 micromoles of photons per square meter per second. ▶ Adding together all the PAR from each second of the day gives the daily light integral, DLI. For ultradwarf bermudagrass, the maximum possible DLI is best. For minimum acceptable quality, the DLI should be at least 30 moles per square meter per day.
3. PPFD meter
4. A sunny day, July 14 2015 0 500 1000 1500 2000 Jul 14 00:00 Jul 14 06:00 Jul 14 12:00 Jul 14 18:00 Jul 15 00:00 Average PPFD by hour, µmol m-2 s-1
5. A cloudy day, July 1 2015 0 500 1000 1500 2000 Jul 01 00:00 Jul 01 06:00 Jul 01 12:00 Jul 01 18:00 Jul 02 00:00 Average PPFD by hour, µmol m-2 s-1
6. 2015-07-01 2015-07-02 2015-07-03 2015-07-04 2015-07-05 2015-07-06 2015-07-07 2015-07-08 2015-07-09 2015-07-10 2015-07-11 2015-07-12 2015-07-13 2015-07-14 2015-07-15 2015-07-16 2015-07-17 2015-07-18 2015-07-19 2015-07-20 2015-07-21 2015-07-22 2015-07-23 2015-07-24 2015-07-25 2015-07-26 2015-07-27 2015-07-28 2015-07-29 2015-07-30 2015-07-31 0 500 1000 1500 2000 0 500 1000 1500 2000 0 500 1000 1500 2000 0 500 1000 1500 2000 0 500 1000 1500 2000 0 500 1000 1500 2000 0 5 10 15 20 Average PPFD by hour, µmol m-2 s-1
7. Monday, October 19 2015 0 500 1000 1500 2000 Oct 19 00:00 Oct 19 06:00 Oct 19 12:00 Oct 19 18:00 Oct 20 00:00 Average PPFD by hour, µmol m-2 s-1
8. Tuesday, October 20 2015 0 500 1000 1500 2000 Oct 20 00:00 Oct 20 06:00 Oct 20 12:00 Oct 20 18:00 Oct 21 00:00 Average PPFD by hour, µmol m-2 s-1
9. 0 10 20 30 40 50 60 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Daily light integral (DLI), mol m-2 d-1 Tokyo: maximum possible (light blue)
10. 0 10 20 30 40 50 60 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Daily light integral (DLI), mol m-2 d-1 Tokyo 2014: maximum possible (light blue) and actual (blue)
11. light blue: maximum possible green: maximum with light saturation at 1000 0 10 20 30 40 50 60 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Daily light integral (DLI), mol m-2 d-1 Tokyo 2014
12. light blue: maximum possible green: maximum with light saturation at 1000 light green: actual with light saturation at 1000 0 10 20 30 40 50 60 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Daily light integral (DLI), mol m-2 d-1 Tokyo 2014
13. light blue: maximum possible green: maximum with light saturation at 1000 light green: actual with light saturation at 1000 blue: actual with no light saturation 0 10 20 30 40 50 60 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Daily light integral (DLI), mol m-2 d-1 Tokyo 2014
14. light blue: maximum possible green: maximum with light saturation at 1000 light green: actual with light saturation at 1000 blue: actual with no light saturation 0 10 20 30 40 50 60 Jan 2015 Apr 2015 Jul 2015 Oct 2015 Jan 2016 Daily light integral (DLI), mol m-2 d-1 Tokyo 2015
15. 25 30 35 40 45 50 -120 -100 -80 Longitude Latitude Atlanta, GA Augusta, GA Watkinsville, GA
16. 0 10 20 30 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Mean daily temperature, ℃ 2014, Watkinsville (green) and Tokyo (blue)
17. 0 10 20 30 Jan 2015 Apr 2015 Jul 2015 Oct 2015 Jan 2016 Mean daily temperature, ℃ 2015, Watkinsville (green) and Tokyo (blue)
18. 0 10 20 30 40 50 60 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Daily light integral (DLI), mol m-2 d-1 Watkinsville 2014: max possible (light blue), actual (green)
19. 0 10 20 30 40 50 60 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Daily light integral (DLI), mol m-2 d-1 Watkinsville 2014: max possible (light blue), actual (green), Tokyo actual (blue)
20. 0 10 20 30 40 50 60 Jan 2015 Apr 2015 Jul 2015 Oct 2015 Jan 2016 Daily light integral (DLI), mol m-2 d-1 Watkinsville 2015: max possible (light blue), actual (green)
21. 0 10 20 30 40 50 60 Jan 2015 Apr 2015 Jul 2015 Oct 2015 Jan 2016 Daily light integral (DLI), mol m-2 d-1 Watkinsville 2015: max possible (light blue), actual (green), Tokyo actual (blue)
22. 0.00 0.25 0.50 0.75 1.00 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Fraction of possible DLI Tokyo 2014
23. 0.00 0.25 0.50 0.75 1.00 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Fraction of possible DLI 2014, Watkinsville (green)
24. 0.00 0.25 0.50 0.75 1.00 Jan 2014 Apr 2014 Jul 2014 Oct 2014 Jan 2015 Fraction of possible DLI 2014, Watkinsville (green) and Tokyo (blue)
25. 0.00 0.25 0.50 0.75 1.00 Jan 2015 Apr 2015 Jul 2015 Oct 2015 Jan 2016 Fraction of possible DLI 2015, Watkinsville (green) and Tokyo (blue)
26. Summary points ▶ ultradwarf bermudagrass can use all the available light ▶ creeping bentgrass reaches its light saturation point at a PPFD of about 1000 ▶ summer temperatures are similar in Japan and the Southeastern USA ▶ the summer DLI tends to be higher in the USA than in Japan ▶ successful management of ultradwarf bermudagrass in Japan considers both temperature and light effects on the turf