Irrigation should be continued long enough to supply plant moisture needs until physiological maturity is reached. This abscission layer forms when hard starch accumulation completes its progression from the top to bottom of a kernel. Seed weight accumulation is complete at this time. Physiological maturity usually occurs about 20 days after dent stage or 60 days after silking. Mississippi grown corn planted during the suggested planting dates normally reaches physiological maturity in early August.
Hard starch begins forming at the kernel tip when denting occurs.
This hard starch layer gradually progresses to the kernel base over the next 20 days. This progession is very important to irrigation scheduling. The milk-line is the borderline between the bright, clear yellow color of the seed coat outside the hard starch layer, compared to the milky, dull yellow of the hard dough layer. Photo of a milk-line. An abscission layer forms when the hard starch layer reaches the kernel base.