The potential of herbaceous native Australian legumes as grain crops: a review

Many agricultural systems around the world are challenged by declining soil resources, a dry climate and increases in input costs. The cultivation of plants that are better adapted than current crop species to nutrient poor soils, a dry climate and low-input agricultural systems would aid the continued profitability and environmental sustainability of agricultural systems. This paper examines herbaceous native Australian legumes for their capacity to be developed as grain crops adapted to dry environments. The 14 genera that contain herbaceous species are Canavalia, Crotalaria, Cullen, Desmodium, Glycine, Glycyrrhiza, Hardenbergia, Indigofera, Kennedia, Lotus, Rhynchosia, Swainsona, Trigonella and Vigna. A number of these genera (e. g., Glycine, Crotalaria, Trigonella and Vigna) include already cultivated exotic grain legumes. Species were evaluated based on the extent to which their natural distribution corresponded to arid and semi-arid climatic regions, as well as the existing information on traits related to harvestability (uniformity of ripening, propensity to retain pod, pod shattering and growth habit), grain qualities (seed size, chemistry, color and the absence of toxins) and fecundity. Published data on seed yield were rare, and for many other traits information was limited. The Australian species of Vigna, Canavalia and Desmodium mainly have tropical distributions and were considered poorly suited for semi-arid temperate cropping systems. Of the remaining genera Glycyrrhiza and Crotalaria species showed many suitable traits, including an erect growth habit, a low propensity to shatter, flowers and fruits borne at the end of branches and moderate to large seeds (5 and 38 mg, respectively). The species for which sufficient information was available that were considered highest priority for further investigation were Glycine canescens, Cullen tenax, Swainsona canescens, Swainsona colutoides, Trigonella suavissima, Kennedia prorepens, Glycyrrhiza acanthocarpa, Crotalaria cunninghamii and Rhynchosia minima.