Selection for rapid germination and emergence may improve wheat seedling establishment in the presence of soil surface crusts

Aims Semi-arid cropping regions are commonly affected by surface crusting of sodic soils, resulting in reduced seedling emergence and grain yield. Although seedlings of different genotypes potentially differ in their ability to emerge through soil crusts, the underlying reasons for these differences remain unclear. Methods Seedling emergence of 38 genotypes of wheat (Triticum aestivum) was investigated in a crusting sodic soil in the glasshouse. Crusts of differing strength (0.78-2.69 kg/cm(2) or 76-263 kPa) and thickness (0.51-2.16 cm) were created using simulated rainfall applied to a representative surface soil with 10% exchangeable Na. Results Wheat seedling emergence decreased as crust strength and thickness increased. For a strong crust, average emergence was 33%, compared to 87% for a weak crust. However, the rate of emergence differed significantly between the 38 genotypes, and it was found that seedlings that germinated comparatively earlier in non-constrained conditions tended to have a higher emergence through soil surface crusts. Conclusion The variability in emergence through soil crusts in seedlings of wheat suggests that genotype selection for improved adaptation may be possible. Rapid seed germination and emergence could potentially be used as a pre-selection criterion for genotypes adapted to soil crust.