Enhancing deep sowing success: Genetic diversity in mesocotyl and coleoptile length, and field establishment of oats (Avena sativa)

Early and deep sowing practices have revolutionised Australian winter cropping. Oats (Avena sativa) are the only winter-cereal with a mesocotyl, potentially allowing them to successfully emerge from deep sowing. This study examined the genetic differences in mesocotyl and coleoptile length, the effect of temperature on these traits, and undertook a field validation of deep-sown oats compared to selected wheat (Triticum aestivum) and barley (Hordeum vulgare) genotypes. A controlled environment experiment on 195 oat genotypes revealed long combined mesocotyl and coleoptile lengths (112-219 mm) with significant genotypic variation. A further controlled environment study compared the mesocotyl and coleoptile lengths of 42 genotypes across four temperatures (15-30°C). This revealed that temperatures exceeding 20°C reduced coleoptile and mesocotyl length by 3.7 mm and 1.1 mm per °C. Five field experiments compared the emergence of 19 oat, four wheat, and two barley genotypes from deep (110 mm) and shallow sowing (40 mm). Oats had greater emergence at depth compared to wheat and barley genotypes. The results indicate that oats are highly suited to early and deep sowing conditions due to their long mesocotyl and combined mesocotyl and coleoptile length.