Comparative performance of barley and wheat across a wide range of yielding conditions. Does barley outyield wheat consistently in low-yielding conditions?

There is a generalised belief that barley is more resilient to stress than wheat. Consequently, land allocation to wheat and barley is based on a presumed differential sensitivity to stresses between these species. Previous field experiments showed that yield of both crops tended to be similar under both low- and high-productivity conditions under Mediterranean environments, but in some particular studies barley advantages are reported. Therefore, the aim of this study was to determine the comparative performance of wheat and barley across a wide range of conditions through the literature published over the first 20 years of this century considering exclusively studies where both cereals had been grown side-by-side in field experiments. We compiled a rigorous database from papers of high-standard journals reporting actual yield data (we excluded simulated yields) measured in experiments under field conditions where both crops were grown side-by-side in the same experiment (excluding studies analysing wheat and barley grown separately). Yield distribution for both species across studies was symmetrical with an average of c. 440 g m- 2 and a range from c. 50-900 g m- 2. The yields of the lowest quartile ranged from 58 to 293 g m- 2, being the comparison of performance in this quartile suitable for detecting differences in low-yielding conditions. Considering individual papers, it is possible to identify any possible outcome of the differential performance of these cereals. However, considering all papers together it was clear that there was not a consistent advantage of barley over wheat at most stressful conditions. Indeed, at very low yielding conditions wheat tended to outyield barley. The trends described above were not influenced by the data-points based on comparisons of barley with the tetraploid wheats, nor by our own experimental data-points. Thus, we confirm in this review that barley does not consistently outyield wheat under low yielding conditions, despite the generalised belief that it does.

Automated summary

There is a belief that barley is more resilient to stress than wheat. However, a review of studies published over the past 20 years shows that there is no consistent evidence to support this belief. In fact, under low-yielding conditions, wheat tends to outperform barley.