Genetically Mediated Changes in the Grain Quality of Single-Cross Maize Hybrids Grown in China

We compared the grain quality of Chinese single-cross maize (Zea mays L.) initially released during the 1960s to 2000s, their parental inbreds, and a set of U.S. hybrids released during the 1960s and 2000s. Chinese hybrids showed lower starch concentrations and higher oil and protein concentrations compared with U.S. hybrids. Chinese hybrids showed a decadal increase of 0.81% in starch concentration, whereas U.S. hybrids showed an increase of 0.57%. Grain quality concentrations of Chinese hybrids exhibited more significant interactions with either planting density or with planting density x environment than did U.S. hybrids. Concentrations of oil, protein, and lysine decreased for Chinese hybrids, which coincided with the introduction and extensive use in China of U.S. maize germplasm during the 1970s and 1980s. Chinese hybrids released during the 1990s had similar kernel compositions to the U.S. hybrids. The kernel quality composition of Chinese hybrids and their mean parent values showed very similar trends during the 1960s to 2000s. Selection for high grain quality parental inbred lines in addition to selection for yield per se will be required if it is deemed important to elevate the grain quality attributes of Chinese maize hybrids.