Selection for Delayed Leaf Senescence in Sugarbeet

Sugarbeet growth is characterized by the continuous dying of old leaves and initiation of new leaves. If the photosynthetic activity of leaves can be extended, fewer leaves may be needed and more photosynthate can be translocated to the root for sucrose production. Two cycles of divergent selection for early and late senescence of the first leaf were conducted in a very heterogeneous population. Significant genetic changes in each direction were obtained for the green leaf duration of the first leaf. Populations produced from the two cycles of divergent selection were evaluated for their effects on canopy in replicated multi-harvest field trials. The early senescing populations had significantly more and smaller leaves than the late senescing populations but equal total leaf area. Root and canopy dry matter were not affected by selecting for extended leaf duration, but selection for reduced leaf duration reduced root dry matter and total dry matter accumulation