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A total of 45 tetraploid-diploid (4x-2x) hybrid progenies were obtained by crossing each of ten diploid parents as males to each of five tetraploid parents. Means of six traits of the 45 progenies obtained from a two-year experiment were used in progeny analysis. A new mathematical model is developed for analyzing the incomplete two-way table. It is modified from the conventional model for factorial mating design. The aim of the model is to evaluate the potential of 2x parents in terms of their mean effects (µi) and sensitivity measures (Bi) to the 4x parents. The 4x parents were treated as testers in the model. They were compared by the estimates of the magnitude of tester effects (gj). The mean effects of 2x parents showed a dominant influence on variation of tuber number and mean tuber weight of the hybrid progenies. They also demonstrated a substantial influence on the variation of total and marketable yield, chipping score and specific gravity. The linear response of 2x parents to 4x parents, however, also showed a substantial influence on the variation of the latter traits. The information on µi and Bi are useful in terms of choosing superior 2x parents and, together with gi of 4x parents, 4x-2x progenies for specific traits. The µi and Bi estimates of the six traits showed a complicated interrelationship to each other. [ABSTRACT FROM AUTHOR]

A total of 45 tetraploid-diploid (4x-2x) hybrid progenies were obtained by crossing each of ten diploid parents as males to each of five tetraploid parents. A relatively low degree of determination (R²) of both 4x and 2x parents on the performance of their 4x-2x hybrid progenies was found for all six traits studied. This implies that test crossing and subsequent progeny analysis is necessary before such parents can be used in a breeding program. Since marketable yield was found to have a higher predictability than total yield, it is the preferred yield trait to be measured. Diploids which produce 2n gametes via FDR usually give rise to 4x progenies with a greater amount of heterosis than similar progenies derived from diploids which produce 2n gametes via SDR, although such heterosis is not necessarily ex-pressed in terms of marketable yield. [ABSTRACT FROM AUTHOR]