Synchronization of Flowering in Corn ( Zea mays L.) by Clipping Young Plants 1

The synchronization of flowering between parents for hybrid seed production is essential for maximum seed yield in corn ( Zea mays L.). In this study, the simultaneous flowering of parental rows planted on the same date was attempted by clipping plants near soil level at three stages of growth. Mean delays for the 28 possible single crosses among 8 inbred lines of 5.5, 7.6, and 6.7 days from planting to anthesis and 5.5, 7.7, and 7.1 days from planting to 50% silking were observed for plants clipped at the 4, 6, and 8‐leaf stages of growth, respectively. The range among single crosses in delay of flowering dates was 4.2 to 6.8 days for clippings at the 4‐leaf stage of growth. Stands were reduced 18, 44, and 25% by clipping at the 4, 6, and 8‐leaf stages, respectively. Yield reductions at these same clipping stages were 11, 38, and 46%. Clipping at the 4‐leaf stage gave the best combination of flowering delay with the least decrease in stand and yield. The combining ability analysis indicated a complex inheritance pattern of factors associated with flowering dates in corn.