marker-assisted selection in wheat - ictsd

Chapter 5 – Marker-assisted selection for improving quantitative traits of forage crops 65changed through marker selection. At highN supply, the performances of NUEplusand NUEmin were fairly similar (Figure 4).The selections also showed striking differencesin field trials in Germany, Englandand the Netherlands. At suboptimal N,the NUEplus selection significantly outperformedits counterpart in yields of drymatter and water soluble carbohydrates,while total N uptake was slightly lower.ConclusionsDivergent mass selection has shown thatmarker selection using a summation indexcan be very effective for difficult andcomplex quantitative traits such as NUE. Acollateral advantage of such an approach isthat it offers a true validation of the putativegenes (QTL) for the traits of interest. Theassociated response to marker selectiondistinctively indicates the presence of truegenes affecting NUE, particularly in thevicinity of markers, which were stronglyaffected by the selection imposed. Theresults also indicate that recurrent massselection to increase the number of positivealleles is worthwhile. The strategy is easilyapplicable in outbreeding crops.AcknowledgementsThe research work was carried out withinthe framework of the EU-FAIR projectNIMGRASS (CT98-4063).Referencesvan Loo, E.N., Schapendonk, A.H.C.M. & de Vos, A.L.F. 1992. Effects of nitrogen supply ontillering dynamics and regrowth of perennial ryegrass populations. Netherlands J. Agric. Sci. 40:401–419.van Loo, E.N., Dolstra, O., Humphreys, M.O., Wolters, L., Luessink, W., de Riek, W. & BarkN. 2003. Lower nitrogen losses through marker assisted selection for nitrogen use efficiency andfeeding value (NIMGRASS). Vorträge Pflanzenzüchtung 59: 270–279.