This is the stage at which corn is harvested for silage. A frost occurring after physiological maturity will have no effect on either grain yield or grain quality. Harvest maturity is a function of grain moisture percentage. Total grain yield and bushel weight have been fixed at physiological maturity. However, grain drying adds to the cost of corn production and, therefore, grain moisture at harvest is the dominant feature in assessing hybrid maturity.
Air temperature is used in quantifying the response of crop development to temperature.
Growing-point temperature should be used although this is much more difficult to monitor. The accuracy of predicting silking date using GDU or CHU was almost double compared to that of calendar days, but the accuracy of those two methodologies was somewhat lower than that of either GTI or TLU in this comparison. Approximate conversions among various relative maturity systems are presented in a table at the bottom of this article . The simple relationship between average daily temperature and GDD accumulation is depicted in Fig. 2 . The relationship between daily temperature and CHU accumulation is depicted in Fig.