Effect of Temperature on In Vitro Kernel Growth of Flint and Dent Maize Hybrids1

Abstract

Most maize (Zea mays L.) hybrids grown in short‐season areas are flint‐dent endosperm types. The so‐called flint hybrids are believed by some to have faster growth rates than dent hybrids at low temperatures. This study was conducted to determine the feasibility of using the in vitro kernel growth technique to investigate the effects of temperature on growth of northern flint and dent maize hybrids. Kernels of three hybrids in one experiment and five hybrids and three inbreds in a second experiment were cultured in vitro on a defined medium at 15, 20, 25, or 30°C. The kernels were removed after 2 to 7 weeks in culture and dry weights were determined. The dent endosperm hybrid ‘King KI108’ had the highest rate of kernel growth at all temperatures, whereas the European flint‐dent hybrid ‘Limagrain LG1’ had the slowest rate of growth. The Canadian flint‐dent hybrid ‘Pioneer 3995’ had an intermediate rate of growth. In one experiment, the differences were more pronounced at low temperatures than at high temperatures. Kernels of inbreds were difficult to culture in vitro, and the growth rates of their kernels were never greater than those of the F1 progenies. The comparison of flint and dent hybrids suggested that a more extensive study of the major groups of maize would result in detection of differences in growth rates of kernels at different temperatures.