HYBRID PERFORMANCE IN WHEAT AS RELATED TO PARENTAL DIVERSITY

The probability of recovering a superior individual from the cross of two inbred parents is greater if both parents are similar in performan ce as opposed to one parent being inferior. Heterosis, coefficients of parentage, and molecular markers have been advocated to assess geneti c diversity directly between parents. This study was done to determine the extent of DNA polymorphisms among a set of seven hard red spring wheats and the relationship between genetic diversity based on these m olecular markers and coefficients of parentage, and to examine the rel ationship between diversity and hybrid performance in a diallel cross of these parents. Parents plus the F-1 hybrids were grown in three env ironments. Grain yield, kernel weight, and protein concentration were measured. Coefficients of parentage, r, were computed for all pairwise combinations of parents. Parents were assayed with 63 sequence tagged site (STS) polymerase chain reaction (PCR) primer sets. Genetic simil arities, GS, were computed using 27 STS PCR primer sets that showed po lymorphisms. Rank correlations were computed between the 1 - r and 1 - GS measures of genetic diversity and F-1 performance, mid-parent hete rosis, and SCA effects. The only significant associations between dive rsity and hybrid performance were those between 1 - r and kernel weigh t SCA effects and heterosis, and protein concentration heterosis. Gene tic diversity was inversely related to heterosis and SCA effects for p rotein concentration. Correlations between the 1 - r and 1 - GS measur es of diversity and hybrid performance traits were of the same sign an d about equal in magnitude. Coefficient of parentage and GS were signi ficantly correlated, and cluster analysis based on the 1 - r and 1 - G S measures of diversity grouped the genotypes similarly. Neither diver sity measure showed promise for predicting F-1 performance, but both m easures provided similar information for grouping and differentiating genotypes.