Langworthy, Adam D. and Rawnsley, Richard P. and Freeman, Mark J. and Waller, Paul A. and Corkrey, Ross and Pembleton, Keith G. and Harrison, Matthew T. and Lane, Peter A. and Henry, David A. (2020) Can irrigating more frequently mitigate detrimental heat wave effects on perennial ryegrass growth and persistence? Agricultural and Forest Meteorology, 291:108074. ISSN 0168-1923
Abstract
Heat waves are problematic for grazing livestock systems in regions dependant on temperate (cool-season) pasture species, owing to the often minimal heat tolerance (thermotolerance) of these pastures. A field experiment in north-west Tasmania, Australia, tested the hypothesis irrigating more frequently reduces detrimental heat wave effects on perennial ryegrass (Lolium perenne L.) above-ground growth and short-term persistence (measured via basal frequency). Heat wave conditions were imposed using freestanding infrared heater arrays fitted with a novel control system designed for evaluating heat wave mitigation options. The control system enabled the extent of warming to be regulated, whilst applying an equal infrared flux (heating) to all heated plots. Increasing the frequency of irrigation events suppressed crown temperature (plant-soil interface) elevation under heaters. When irrigation was applied every 2, 5 or 10 days, median crown temperature elevation under heaters equalled 5.5 °C, 6.5 °C and 7.0 °C, respectively. However, detrimental effects of imposed heat wave conditions on perennial ryegrass growth were not mitigated by more frequent irrigation events. This resulted from the small differences in crown temperature elevation between irrigation frequency treatments, combined with supraoptimal crown temperatures occurring <10% of the time during the simulated 10-day heat wave events. The infrequent occurrence of supraoptimal crown temperatures: (i) resulted from mild ambient conditions (mean ambient air temperature, 17.2 °C); and (ii) explains why applied heating only reduced perennial ryegrass growth by 13 kg DM ha−1 day−1 (23%) when heaters were operated, with no residual effect in the accompanying recovery regrowth cycle. Applied heating also had no appreciable effect on perennial ryegrass basal frequency. Under more extreme heat wave conditions, irrigation frequency may have a larger effect on perennial ryegrass tissue temperature and subsequent growth, especially in environments characterised by higher crown temperatures.
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| Item Type: | Article (Commonwealth Reporting Category C) |
|---|---|
| Refereed: | Yes |
| Item Status: | Live Archive |
| Faculty/School / Institute/Centre: | Current - Faculty of Health, Engineering and Sciences - School of Sciences (6 Sep 2019 -) |
| Faculty/School / Institute/Centre: | Current - Institute for Life Sciences and the Environment - Centre for Sustainable Agricultural Systems (1 Aug 2018 -) |
| Date Deposited: | 28 Jul 2020 03:50 |
| Last Modified: | 31 Jul 2020 01:55 |
| Uncontrolled Keywords: | Climate change; Forage; Heatwaves; South-eastern Australia |
| Fields of Research (2008): | 07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070302 Agronomy 07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070303 Crop and Pasture Biochemistry and Physiology |
| Socio-Economic Objectives (2008): | B Economic Development > 83 Animal Production and Animal Primary Products > 8304 Pasture, Browse and Fodder Crops > 830406 Sown Pastures (excl. Lucerne) |
| Identification Number or DOI: | https://doi.org/10.1016/j.agrformet.2020.108074 |
| URI: | http://eprints.usq.edu.au/id/eprint/39083 |
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