GENETIC-DIVERGENCE FOR CROSS PREDICTION IN POTATO

To study the effectiveness of genetic divergence for cross prediction in potato, progeny means, heterosis and specific combining ability eff ects were correlated with parents' genetic distances (D values) estima ted under six in vitro and four in vivo conditions, for tuber yield in 72 crosses (18 x 4) of 22 parents under autumn crop conditions for th ree successive generations. Genetic distances under in vitro condition s had no relationship with the progeny means for tuber yield. Whereas, those under in vivo conditions in the autumn seasons were positively associated with the progeny means. Similarly, heterosis for tuber yiel d had a stronger relationship with genetic distances based on an in vi vo crop than those based on an in vitro crop. All correlation coeffici ents between genetic distances and specific combining ability effects were non-significant. The magnitudes of the significant correlation co efficients showed that genetic divergence can be used as an indirect p arameter of moderate effectiveness in selecting parents to produce het erotic high yielding progenies. Such cross predictions, however, would be effective only if parents are evaluated under the conditions simil ar to those under which crosses are likely to be evaluated.