Higher rust resistance and similar yield of oat landraces versus cultivars under high temperature and drought

Oat crop is not particularly well adapted to hot and dry weather, as shown by a 3-fold yield reduction in Mediterranean compared to Northern regions. As a consequence, there is a need to identify more resilient oats adapted to current Mediterranean and future climate conditions. Here, we studied the performance of oat landraces under Mediterranean conditions, including the resistance to their most devastating disease, the crown rust. One hundred forty-one genetically characterized Spanish landraces were evaluated over two crop seasons at four contrasting locations in Spain and Egypt. Genotype-environment interactions were studied using heritability-adjusted genotype plus genotype-environment biplot analyses. The impact of climate variables on agronomic traits and the adaptation of particular landraces to environmental factors were inferred from non-metric multivariate scaling and canonical correspondence analyses. Results show an average oat landrace grain yield of 1500 kg/ha, which is similar to the mean yield of commercial varieties. Nonetheless, commercial varieties had 20% higher harvest index than landraces, which is explained by the higher biomass of landraces. Moreover, oat landraces showed high levels of rust resistance with mean values of the area under the disease curve of 2.58, which is approximately 25% lower than that of commercial varieties. Furthermore, several landraces carried a broad spectrum type of resistance which is expected to be more durable and efficient against different rust isolates.