XENIA AND MATERNAL EFFECTS ON MAIZE KERNEL DEVELOPMENT

Maize (Zea mays L.) kernel mass is a primary grain yield component controlled by genes from both the pollen and the maternal plant. We studied the contribution of genes attributable to kernel weight difference when inherited through the pollen versus the plant. We measured grain-filling characteristics, kernel moisture concentration, rate of moisture loss, and mature kernel dry weight for apical, mid-ear, and basal kernels of field-grown plants. We produced 12 hybrid strains by reciprocally intercrossing three strains that differ for grain-filling rates [high (HC), random (RC), and low (LC) R-nj color expression] with two kernel-weight strains [large (LG) and small (SM)]. Plants of each hybrid strain were pollinated with either LG or SM pollen in Fargo, ND, in 1990, 1991, and 1992. Multivariate analyses of variance showed that LG and SM pollen effects differed for rate of grain filling, lag phase duration, and kernel dry weight. Kernels from LG pollen had 0.4% shorter lag phases, grew 5.2% faster, and were 3.9% heavier at maturity than kernels from SM pollen. Developmental similarities among apical, mid-ear, and basal kernels suggested that a common assimilate supply controlled their growth. Kernels from LG plants had 2.6% higher grain-filling rates, 5.9% longer effective filling periods, 0.7% shorter lag phases, 7.6% heavier mature kernels, and 23 g kg(-1) lower moisture concentration at physiological maturity than kernels from SM plants. We found reciprocal effects among hybrid plants for all traits. Kernel-weight genes produced xenia effects for three traits determining kernel dry weight, but affected many additional traits when inherited via the plant.