Description
The forage yield and pasture persistence benefits of Epichloë fungal endophyte strain AR37 (AR37) in high rainfall perennial ryegrass (Lolium perenne) pastures in Australia and New Zealand are recognised. However, the effect of beneficial endophytes on nitrogen (N) use efficiency, yield response to applied N and N uptake had not been determined.
To investigate this, a replicated trial was managed for three years under irrigation in southern Australia. Five N application rates (0, 20, 40, 80 and 160 kg N/ha) were applied every second harvest to a tetraploid perennial ryegrass variety with and without AR37. Ryegrass biomass was determined by full plot harvest and N percentage determined by near infrared spectroscopy.
AR37 caused an increase in perennial ryegrass N use efficiency (the slope of the N response function) in all seasons, with the average increase in marginal response being 2.1 kg DM/kg N or 29.6 % over three-years. Benefit at individual harvests ranged from 0.2 to 6.5 kg DM/kg N. Foliage N percentage was not influenced by AR37 infection, thus AR37 caused enhanced N uptake due to increased forage yield.
This trial demonstrates AR37 can contribute to the profitable and sustainable intensification of high rainfall perennial ryegrass pastures by significantly increasing the marginal yield response to N, and the uptake of applied N fertiliser. Further, increased N uptake caused by AR37 will likely have implication for negative environmental externalities associated with N use (leaching, runoff and nitrogenous greenhouse gas emissions) which warrants further investigation, along with research to clarify biotic and abiotic drivers of observed results.
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Improvement in the Nitrogen Use Efficiency and Uptake of Perennial Ryegrass (Lolium perenne) Caused by the Epichloë Fungal Endophyte AR37
The forage yield and pasture persistence benefits of Epichloë fungal endophyte strain AR37 (AR37) in high rainfall perennial ryegrass (Lolium perenne) pastures in Australia and New Zealand are recognised. However, the effect of beneficial endophytes on nitrogen (N) use efficiency, yield response to applied N and N uptake had not been determined.
To investigate this, a replicated trial was managed for three years under irrigation in southern Australia. Five N application rates (0, 20, 40, 80 and 160 kg N/ha) were applied every second harvest to a tetraploid perennial ryegrass variety with and without AR37. Ryegrass biomass was determined by full plot harvest and N percentage determined by near infrared spectroscopy.
AR37 caused an increase in perennial ryegrass N use efficiency (the slope of the N response function) in all seasons, with the average increase in marginal response being 2.1 kg DM/kg N or 29.6 % over three-years. Benefit at individual harvests ranged from 0.2 to 6.5 kg DM/kg N. Foliage N percentage was not influenced by AR37 infection, thus AR37 caused enhanced N uptake due to increased forage yield.
This trial demonstrates AR37 can contribute to the profitable and sustainable intensification of high rainfall perennial ryegrass pastures by significantly increasing the marginal yield response to N, and the uptake of applied N fertiliser. Further, increased N uptake caused by AR37 will likely have implication for negative environmental externalities associated with N use (leaching, runoff and nitrogenous greenhouse gas emissions) which warrants further investigation, along with research to clarify biotic and abiotic drivers of observed results.
