GENETIC-CONTROL OF AMYLOSE CONTENT IN A DIALLEL SET OF RICE CROSSES

Models proposed by Gale and Pooni, Kumar and Khush are applied to stud y the inheritance of amylose content in a diallel set of crosses produ ced from seven elite inbred lines of indica rice representing all the major rice consuming regions of the world. In theory, the standard (Ha yman's and Griffing's) analyses of diallel tables and the. Wr/Vr relat ionship are found to apply even though the trait under investigation i s expressed in a triploid state. It is further revealed that reciproca l effects can only be detected unambiguously in the F-2 diallel and th e additive and non-additive effects cannot be separated in the B-1 and B-2 diallels when they are analysed separately. Analysis of the exper imental data reveals that additive and dominance effects are the main sources of variation among the 21 crosses of the 7 x 7 diallel. Compar isons of the B-1 and B-2 diallels also show that the single dosage dom inance (h(a1) type) effects differ significantly from the double dosag e dominance (h(a2) type) effects. In addition, cytoplasmic control of amylose content is confirmed unambiguously and a large proportion of t he heritable variation is shown to be controlled by a series of multip le alleles with large effects.