Photoperiod sensitivity during stem elongation as an avenue to raise potential yield in wheat

Worldwide wheat yields have been only slightly, and non-significantly, incr easing during the 90's, suggesting that they may be levelling off. Consider ing that there is consensus that large new growing areas will be not introd uced and management improvements will be increasingly harder to obtain, gen etic improvement would play a more important role to keep rising wheat yiel ds in the future than in the past. In this scenario, the use of physiologic al bases as a complementary tool to identifying alternative ways for breedi ng seems to be crucial for breaking the apparent barriers in wheat yields. In this presentation, we attempted to envisage, from published and recent u npublished evidences from our lab, using studies carried out under both con trolled and field conditions, some opportunities to manipulate the rate of crop development during the late reproductive phase. This phase has been re cognised as critical in terms of yield generation, and the idea of manipula ting its response to photoperiod as a tool for increasing yield potential i n wheat is reviewed.