Characterization of grain-filling patterns in diverse maize germplasm
Information regarding genotypic variability for maize (Zea mays L.) grain-filling patterns is scarce, especially at the inbred level. We characterized a large set of public and elite proprietary inbred lines for kernel growth traits. Lines were selected to sample divergent kernel size, genetic diversity, and lines released from breeding programs. The traits characterized were final kernel weight (KW), kernel growth rate (KGR), grain-filling duration (GFD), maximum water content and moisture concentration (fresh weight basis) at physiological maturity. We evaluated 32 inbred lines in 2006 and 35 inbred lines in 2007. Kernel weight ranged from 104 to 317 mg per kernel in 2006 and from 96 to 327 mg per kernel in 2007. Variation in KW was achieved through different combinations of KGR (0.14 to 0.44 mg °Cd–1 kernel–1) and GFD (610 to 1137 °Cd). There was no correlation between KGR and GFD. Moisture concentration at physiological maturity showed significant genotypic differences (p < 0.001), ranging from 280 to 600 g kg–1. A previously described framework for predicting kernel growth patterns based on kernel water accumulation was tested for accuracy and differences were observed (p < 0.01), suggesting that a general pattern cannot be used to describe all the genotypic variability available. Results demonstrate the high variability in KW across elite and public maize inbreds, reflecting a wide range of KGRs and GFDs.