"Effects of sowing depth and press wheel pressure on wheat establishment and yield in drying surface soil – Wagga Wagga 2024"

Abstract

Key findings • Press wheel spring pressure between 2.05 kg/cm and 2.93 kg/cm did not influence emergence rate and final plant number, despite increasing soil strength from 0.39 kg/cm2 to 0.46 kg/cm2. • Coleoptile length (CL) measured in the field correlated with plant emergence rate (r = 0.61, P = 0.046) and final establishment number (r = 0.42, P = 0.04) in both drying and watered soil seed beds. • Sowing into drier soil reduced plant numbers across all treatment groups (P<0.001), with longer CL genotypes showing an 8% higher establishment rate compared to shorter CL genotypes. • Deep sowing delayed heading (GS59) from one to 4 days across genotypes (P<0.001), with the highest press wheel pressure delaying heading by 3 days on average (P = 0.002) compared to the mean of all press wheel treatments. • Total biomass at maturity was not associated with sowing depth or established plant number, but was linked to press wheel pressure where the highest pressure at shallow sowing reduced soil moisture loss. Greater soil moisture led to taller plant heights of 3–4 cm on average (P = 0.013), but decreased harvest index by 7% (P = 0.029). • Grain yield response to sowing depth and press wheel pressure at sowing showed variable results that were largely dependent on genotype. Large-seeded Magenta[PBR] and Magenta13 benefited from soil moisture at deeper sowing and produced higher yields compared to shallow sowing (P = 0.036). In contrast, this pattern was reversed with Mace[PBR] and Mace18. Press wheel pressure also seemed to have minor, genotype-dependent effects, with all genotypes generally tending to yield more under lighter pressure when deep-sown (though not significantly, P = 0.29). Magenta[PBR], Magenta13 and Mace18 exhibited a trend for increased yield with heavier press wheels under shallow sowing.