Effect of Kernel Maturation on Subsequent Seedling Vigor in Maize1

Abstract

Production of high quality seed corn (Zea mays L.) would be facilitated by the harvesting of the seed at a kernel maturity which is highly correlated with maximum seedling vigor. This study attempted to correlate several kernel maturity indices with measures of seedling vigor in a maturing seed corn crop.Hybrid seed samples were taken from two field locations of production of maternal parents ‘A632’, ‘Va26’, ‘B73’, and ‘Mo17’ from 35 days to 98 days after silking. Kernel maturity indices evaluated were: 1) fresh kernel respiration rates, 2) black layer development, 3) moisture percentage, and 4) dry weight accumulation. After drying, the seed was grown on moistened, rolled paper towels in the dark for seven days at 25 C. Vigor measurements included germination percentage, shoot dry weight, and root dry weight. Although germination percentages were high over all harvest dates, both shoot and root dry weight were highly dependent on date of harvest. Distinct vigor maxima and minima were noted, and the first and last sample dates never corresponded to maximum shoot and root dry weight. Dates of maximum vigor and kernel maturity patterns were specific for each hybrid. Maximum kernel dry weight was correlated with maximum shoot and root dry weight, and the range of kernel moisture percentage corresponding to initial attainment of maximum kernel dry weight was small.