Emergence, survival, biomass production, and seed production of Chloris truncata (windmill grass) in the Western Australian wheatbelt

Abstract

Chloris truncata is a C4 grass species, native to Australia. Within the wheatbelt of Western Australia (WA), it is a weed of grain cropping systems and a beneficial forage species within pasture systems. Plant emergence, density, survival, biomass production, seed production, and seed germinability were investigated, in pasture or cropping systems, at two trial sites (in Merredin, WA) over two years (from 2007 to 2009). Chloris truncata predominantly emerged and set seed during spring and early summer. This species is usually referred to as a short-lived perennial, and could survive for >14 months, but predominantly grew as a spring/summer annual in the WA wheatbelt. Maximum plant density, biomass, and seed production were, respectively, 4.2–28.2 plants/m2, 8.3–146.1 g dry biomass/m2, and 3325–61 383 seeds/m2, depending on location. Cohorts emerging in spring produced more seeds than those that emerged during other seasons. Average seed germinability reached a maximum of 62%, following an initial 3–4-month period of dormancy. There are few herbicides to control plants growing within the winter/spring annual grain crops, and so further research into increased crop competitive ability is required to reduce growth of spring cohorts and potentially reduce seed set. However, the biomass produced by C. truncata (range 0–1460 kg/ha) can be used as forage in a pasture system, or over the summer/autumn feed gap in a cropping system.