A tale of two winters: Comparison of winter survival and senescence rates in perennial ryegrass tillers in the field and under simulated winter conditions in a growth chamber.

  • Oral Presentation
  • Plant Growth and Development
  • 13 Jun 2018 10:40
  • FS-G01, UCD Agriculture and food science Centre
  • View all IPSAM abstracts

Caitlin Rita Looney*
University College Cork

Michael Egan

Deirdre Hennessy

Astrid Wingler
University College Cork

*Presenting Author

Perennial ryegrass (Lolium perenne L.; PRG), is the most desired plant species in pasture-based production systems in Ireland as it suits the temperate climate and intensive grazing. A PRG sward is made up of individual tillers which survive for approximately 12 months. Tiller appearance (TA) and survival (TS) in PRG is influenced by temperature, age and shading. Tissue turnover happens continuously during winter. Tiller appearance, TS, and leaf senescence rate (LSR) were measured over winter (October 2017 – January 2018) in a paddock system (PS) (mean temp.; 7.81˚C; range 0-17˚C) compared with a growth chamber (GC) with an ambient temperature of 5.8˚C (average winter temp 2009-2015). A paddock was grazed on September 30thand three 1 m transects were chosen at random and individual PRG tillers were selected at 10 cm intervals and marked. Four 12 cm × 12 cm turves were taken from the same paddock and three PRG tillers were marked on each and transferred to the GC. Measurements were undertaken on three occasions over the measurement period (M1, M2 & M3). There was a significant difference (P<0.01) between TS in the GC and the PS. Marked TS was 60% in the PS and 100% in the GC. There was a significantly greater TA in the PS compared to the GC (P<0.001). Fifty-one tillers appeared in the PS, however only 33 daughter tillers survived to the end of the measurement period, with no new tillers recorded in the GC. The LSR was significantly greater (P<0.01) on the PS (8.3, 8.6 & 5.0 mm tiller ̄ ¹day ̄¹) compared to GC (2.2, 0.2 & 2.2 mm tiller ̄ ¹day ̄¹) for M1, M2 and M3, respectively. The differences observed in the current study in the PS could be due to higher temperatures which increases tillering but fluctuations in temperature may have caused significant death and senescence in both new tillers that have not fragmented and established daughter tillers.