Understanding the diversity in yield potential and stability among commercial sorghum hybrids can inform crop designs

Abstract

Reducing yield gaps in dryland cropping depends on our capacity to identify combinations of genetics (G) and management (M) (i.e. crop designs, G × M) that best suit site and seasonal conditions (the environment, E). We combined empirical and modelling approaches to characterise and explain the yield stability and yield potential of commercial sorghum hybrids when grown under a range of agronomic managements and environments yielding between 3 and 12 t ha. The empirical data includes two seasons (2014-15 and 2015–2016) of on-farm and on-research station trials conducted across six sites in Queensland, Australia. Agronomic management treatments included plant density, row configuration, level of irrigation and fertiliser inputs, and time of sowing. Six hybrids contrasting in maturity and tillering type were characterised relative to the industry standard MR-Buster in terms of yield potential, yield stability (b), and an expected utility index that combines both indices. A medium-late maturity and high tillering hybrid (MR-Scorpio), had the highest utility rank and showed high b values due to high tiller productivity. A variety of significant row spacing and configuration, and plant density effects on yield were observed, but these were inconsistent across sites and seasons. A long-term simulation experiment across contrasting environments was used to identify hybrid traits and managements capable of modifying yield stability. Combined with the empirical data, the simulations suggest hybrids showing high biomass production and multiple productive tillers can increase the response of yield to the productivity of the environment, whereas reducing the thermal time to floral initiation may increase the stability of yields across environments. Expected changes in hybrid rank due to such G × E interactions, along with the complex effects of management on yield, increase the need to match crop design to specific sites and seasons. The value of targeted crop design depends on the diversity of traits among commercial hybrids and the availability of a skilful seasonal climate forecast to allow farmers to match hybrids and management to prevailing and expected seasonal conditions.