Pollen effect (xenia) for evaluating breeding materials in maize

Pollen effect (xenia) plays an important role in modifying biochemical constituents of maize (Zea mays L.) kernels. The objectives of this study were to i) evaluate the effect of filial generations on certain genetic estimations; ii) compare general (GCA) and specific combining ability (SCA) effects obtained from Griffing’s diallel analyses between parental (F0) and F1 generations; iii) determine the relationships between pollen effect and genetic estimations; and iv) examine the possible utility of pollen effect for improving kernel-quality traits (protein and oil contents). We conducted two experiments (F0 in 2011 and F1 in 2013) and examined kernel protein and oil contents. Individual pollen effects (IPE) and specific individual pollen effects (SIPE) were computed. The results showed that entries (E) and filial generations (G) and E × G interaction variances were significant for both protein and oil contents, whereas changes in genetic estimates between generations were highly variable. The signs and magnitudes of GCA effects were similar and highly correlated (r > 0.80) between F0 and F1 generations for all four diallel methods. In addition, GCA effects were highly correlated with IPE estimates for all four diallel methods. Specific combining ability (SCA) estimates between F0 and F1 generations were moderately correlated (r = 0.50) in Method IV for oil and highly negatively correlated (r = -1.00) in Method III for protein content. Heterosis analyses showed that hybrids could not be evaluated on the basis of the F0 generation to predict their F1 performances. Individual pollen effects between generations showed higher correlation for protein content (r = 1.00) than for oil content (r = 0.40). Specific individual pollen effects of parents were also slightly higher for protein content (r = 0.74) than for oil content (r = 0.62). We concluded that the direct or indirect utilization of pollen effect (xenia) was possible for parental evaluation but not suitable for hybrid evaluation for kernel oil and protein contents.