What is Physiological maturity (black layer)?
The dark black layer that forms at the kernel base shows that the flow of nutrients from the plant into the kernel has stopped. From then on kernel weight does not increase; the kernel only loses moisture.
Kernel moisture at physiological maturity is usually around 30–35%, so for grain harvest the kernels still need to dry in the field or in a drying facility. Silage is harvested before physiological maturity.
Why does it matter when choosing seed?
A variety’s maturity rating (FAO group, CRM or the days to maturity stated on the sheet) determines whether the plant can reach physiological maturity within your area’s growing season.
CasSeed varieties related to this topic
The relevant characteristics are listed on each variety’s technical sheet.
FAO 650–700 · Silage maize seed
265–300 cm plant height and 9–10 t/da silage yield; also suited to starch and feed industries.
Related terms
FAO maturity group
The FAO maturity group is a numerical scale that classifies maize varieties by the time they need to mature; the higher the number, the later the variety matures.
Dry-down
Dry-down is the rate at which maize kernels lose moisture in the field after physiological maturity.
Silage maize
Silage maize is maize grown so that the whole plant (stalk, leaves and ear) can be chopped, fermented in airtight conditions and stored as animal feed.