Dr Sarah Rich1, Ed Barrett-Lennard2, Mr Josh Hendry1, Matthew Wilmont1, Hayley Norman1
1CSIRO, Floreat, Australia, 2DPIRD, South Perth, Australia
Biography:
Sarah is a plant physiologist who works across a broad range of areas related to resilient farming systems. Her key research interests include crop germination, emergence and establishment in the context of GxExM, and root morphology/physiology and the impact of belowground processes on crop success.
Abstract:
Across southern Australia, there has been uptake in planting perennial plants such as oldman saltbush (Atriplex nummularia) to fill summer/autumn feedgaps in livestock production systems. Oldman saltbush is a halophytic, woody, native shrub that is adapted to saline and arid conditions. There is a need to better understand the agronomic practices that will optimise edible biomass production and nutritional value of these plantings. The objective of this project was to assess the influence of nitrogen (N) and salt (as NaCl) concentrations on the growth and nutritional value of oldman saltbush, under both glasshouse and field conditions.
A glasshouse experiment was conducted on 2-year-old shrubs to ascertain growth responses to five levels of nitrogen (N) and three salinity levels (NaCl). Under these controlled conditions, addition of N significantly increased edible biomass, even under high salinities, where the N presumably acted to bolster salinity tolerance mechanisms. A threshold level of 5 mM of N was found beyond which edible biomass did not continue to increase, although this interacted with salinity, being 2.5 mM of N at high salinity. Two field experiments were run to investigate the use of N to boost biomass, with inconclusive results. These experiments highlight the benefits of nitrogen management for saltbush planting, especially when growing them on marginal saline country but wide, deep root systems may mean older shrubs can access nitrogen from depth.