Themeda Triandra as a Perennial Seed Crop in South-Eastern Australia: What Are the Agronomic Possibilities and Constraints, and Future Research Needs?

Abstract

The development of native perennial seed crops is an area of increasing interest in Australia. Key reasons for this include potential production of high-value seed for land restoration and emerging niche food markets, the cultural significance that native plants hold for Aboriginal people, reduced farm input costs in comparison to annual seed crop production and potential environmental benefits from diversified agricultural systems. One species of interest is Themeda triandra, a C 4 perennial tussock grass that dominated many grasslands and grassy woodlands across Australia prior to European invasion. This review aims to inform those seeking to grow T. triandra as a seed crop in south-eastern Australia of the genetic, environmental and management factors that influence plant growth, development, and seed yield. By doing so, the review highlights the agronomic possibilities and constraints relating to production of a T. triandra as a seed crop and identifies future research needs. Key agronomic possibilities include the requirement to establish a crop once that can then persist for years; its adaptation to a range of environments and its ability to produce high-value seed every year. Key agronomic constraints include low and variable seed yields, limited knowledge of important aspects of crop management and difficulties in broadacre crop establishment associated with its seed diaspore morphology, low seed quality, germination requirements and weed competition. Future research should investigate ways to maximise seed production through effective crop management, improve upon current sowing and harvest techniques and identify ecotypes with agronomic traits preferable for seed crop production.