Xenia effects in maize with normal endosperm: I. Importance and stability

Xenia is the effect of pollen on the development and characteristics of the fruits. To reexplore its importance and consequences for grain production in maize (Zea mays L.), the effect of pollen genotype on kernel weight was studied with five white kernel lines as females and several yellow kernel l ines as males in a factorial (5 x 20) and in a diallel (5 x 5) mating desig n. White single-cross hybrids were also used as females. Cross-fertilizatio n advantage was studied in 1993, 1994, and 1995 by mixing pollen from a mal e and pollen from a female (i.e., autopollen). When inbred lines were used as females the average increase in kernel weight at maturity, because of cr oss fertilization, was 13% in 1993, 11% in 1994, and 11.5% in 1995. Female effects were the strongest; however, male and female x male interaction eff ects were also significant although at the limit of significance because of large environmental variation. These effects were also significant for whi te kernels, showing that there was a stimulation effect on the filling of k ernels from self fertilization by the more active billing of kernels from c ross fertilization. With single-cross females, cross-fertilization advantag e was about halved. Despite genotype X year interaction, the phenomenon see ms sufficiently repeatable with significant correlation among years. Result s are interpreted as an early manifestation of heterosis which increases si nk strength of kernels from cross fertilization.