R‐Navajo Kernel Color Expression as a Selection Criterion in a Sugary 2; Opaque 2 Maize Synthetic

Abstract

Grain yield increases have been reported from indirect selection for increased anthocyanin aleurone coloration by use of R‐Navajo (R‐nj) allele in early maize (Zea mays L.). This study was conducted to determine if divergent selection for high and low R‐nj kernel aleurone coloration indirectly effected correlated responses for grain yield and other agronomic traits in a sugary‐2;opaque‐2 (su2;o2) Iowa Super Stiff Stalk Synthetic (BSSSS). The normal synthetic was converted by crossing inbred B37 su2;o2 with BSSSS, then backcrossing to BSSSS for three generations followed by two generations of randomating with selection of the heterozygous su2;o2 ears. The homozygous su2;o2 kernel segregants were selected from the random mated heterozygous BSSSS population to constitute a base population on which divergent selection was initiated. Three cycles of divergent mass selection for both high and low R‐nj coloration were obtained. All cycles of selection and a check were evaluated in two‐row plots in a randomized complete‐block design with five replications at two locations in 1983 and one location in 1984. Significant differences between the regression coefficients of grain yield and kernel density on number of cycles for high and low color expression were observed, but the coefficients themselves were not significantly different from zero. Yield increased in the upward direction only 0.061 Mg ha−1 cycle−1. Cycles of selection apparently had no effect on 100‐kernel weight, 100‐kernel volume, harvest grain moisture, duration of grain fill, measured in growing‐degree‐day units (GDD), or maturity from planting to physiological maturity (GDD). This indirect selection procedure did not appear to be very effective for increasing grain yield.