RFLP mapping of genes controlling yield components and plant height in an indica x japonica DH population of rice

We assessed the number and distribution of QTLs for several quantitative traits contributing to yield elaboration (panicle number, number of grains per panicle, sterility, and thousand grain weight) and to plant stature (plant height, panicle length, and panicle exsertion). We evaluated a population of 110 DH lines derived from an indica x japonica cross (IR64/Azucena) for these traits, under irrigated conditions in a replicated trial. An RFLP map with 135 polymorphic markers had been previously established for this population. Between 8 and 12 QTL were found associated with each yield component with relatively few QTL shared between traits. Eight QTL were identified for the yield per plant which is comparatively less than one would have expected for such a complex trait. One reason could be that the number of panicles per plant and the number of spikelets per panicle were strongly negatively correlated in the population and acted in a compensatory way with neutral effect on yield. However, most of the QTL involved in yield control were also involved in the control of at least one of the yield components. Twelve QTL were associated with plant height, some being common with those linked with exsertion and panicle length, probably due to pleiotropic effects. One segment, explaining the major part of the variability, is located on a region of chromosome 1 also known to include sd-1, a major gene affecting plant height. We compare the number of QTL identified with the effective number of genes involved as defined by quantitative genetics models. We discuss further steps to confirm these putative QTL and the usefulness of markeraided selection for these traits.