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Can irrigating more frequently mitigate detrimental heat wave effects on perennial ryegrass growth and persistence?

Citation

Langworthy, A and Rawnsley, RP and Freeman, MJ and Waller, PA and Corkrey, R and Pembleton, KG and Harrison, MT and Lane, PA and Henry, DA, Can irrigating more frequently mitigate detrimental heat wave effects on perennial ryegrass growth and persistence?, Agricultural and Forest Meteorology ISSN 0168-1923 (In Press) [Refereed Article]

Copyright Statement

2020 Elsevier B.V. All rights reserved.

DOI: doi:10.1016/j.agrformet.2020.108074

Abstract

Heat waves are problematic for grazing livestock systems in regions dependent 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 simulated 10 day heat wave events. The infrequent occurrence of supraoptimal crown temperatures: (i) resulted from mild ambient conditions (mean ambient air temperature, 17.2C); 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 temperature and subsequent growth, especially in environments characterised by higher crown temperatures.

Item Details

Item Type:Refereed Article
Keywords:dairy, heat stress, perennial ryegrass, irrigation, climate change, forage, heatwaves, south-eastern Australia
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Agronomy
Objective Division:Animal Production and Animal Primary Products
Objective Group:Livestock raising
Objective Field:Dairy cattle
UTAS Author:Langworthy, A (Mr Adam Langworthy)
UTAS Author:Rawnsley, RP (Dr Richard Rawnsley)
UTAS Author:Freeman, MJ (Mr Mark Freeman)
UTAS Author:Waller, PA (Mr Paul Waller)
UTAS Author:Corkrey, R (Dr Ross Corkrey)
UTAS Author:Pembleton, KG (Dr Keith Pembleton)
UTAS Author:Harrison, MT (Associate Professor Matthew Harrison)
UTAS Author:Lane, PA (Associate Professor Peter Lane)
UTAS Author:Henry, DA (Dr David Henry)
ID Code:138774
Year Published:In Press
Deposited By:TIA - Research Institute
Deposited On:2020-04-29
Last Modified:2020-07-22
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