Awns increased the ear surface area from 36 to 59%, depending on their length, which ranged from 5.5 to 13.8 cm. This resulted in an average 4% more radiation intercepted by the awned ears. Canopy temperature was 0.9°C lower, on average, in the awned isolines, and was negatively correlated with kernel weight (r = –0.85**, n = 10), although consistent and marked effects of awns on canopy temperature were only observed in the long-awned lines. Awns positively affected grain yield, with an average increase of 10 and 16%, respectively, in the 2 years in which they affected kernel weight. The irrelevant effect of awns on yield in the year characterised by a severe drought was a consequence of their early desiccation.

The effects of awns on grain yield and kernel weight strongly depend on the genetic background, on awn length and functionality, and on the environmental conditions during grain filling.