Established plant density
The established plant densities were nearly 47% of the targeted plant densities. Hyola 450TT established significantly (p<0.05) higher plant numbers than GT Viper at higher seeding rates (Figure 1).
Grain yield and gross margins
All varieties responded to increasing plant density. However, the response started to flatten at about 15 plants/m2 for Roundup Ready GT Viper and Hyola 404RR varieties and at about 30 plants/m2 for open-pollinated ATR Stingray and Hyola 450TT varieties (Figure 2). The economic optimum plant density for both Roundup Ready GT Viper and Hyola 404RR was 19 plants/m2 and for the Triazine Tolerant ATR Stingray and Hyola 450TT it was 52 and 24 plants/m2, respectively. Hyola 404RR was the highset yielding variety (1624kg/ha) but ATR Stingray produced highest gross margins of $574/ha. Averaged over the densities, the gross margins of other varieties ranged from $470-$555/ha.
Roundup Ready varieties GT Viper and Hyola 404RR and Triazine Tolerant hybrid Hyola 450TT had lower economic optimum plant densities (19-24 plants/m2) than ATR Stingray (52 plants/m2 ). Although Hyola 404RR was highest yielding, ATR Stingray produced the highest gross margins. In this trial weeds were effectively managed in both RR and TT groups.
This trial (13GS19) is one of a series conducted throughout WA as part of the GRDC/DPIRD co-funded project 'Tactical break crop agronomy'. Thanks to Paul Hicks for hosting the trial and to the Katanning Research Support Unit for trial management.