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 lines as males in a factorial (5 × 20) and in a diallel (5 × 5) mating design. White single‐cross hybrids were also used as females. Cross‐fertilization advantage was studied in 1993, 1994, and 1995 by mixing pollen from a male 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 cross fertilization, was 13% in 1993, 11% in 1994, and 11.5% in 1995. Female effects were the strongest; however, male and female × male interaction effects were also significant although at the limit of significance because of large environmental variation. These effects were also significant for white kernels, showing that there was a stimulation effect on the filling of kernels from self fertilization by the more active filling of kernels from cross fertilization. With single‐cross females, crossfertilization advantage was about halved. Despite genotype × year interaction, the phenomenon seems sufficiently repeatable with significant correlation among years. Results are interpreted as an early manifestation of heterosis which increases sink strength of kernels from cross fertilization.