During which reproductive stage does corn reach physiological maturity?

Physiological maturity in corn is reached during the reproductive stage known as R6. At this stage, the kernels attain their maximum dry weight, the black layer forms at the kernel tip, and the plant stops transferring nutrients to the kernels. It is a critical point because it signifies that the plant has completed its reproductive growth, and the kernels are now fully developed.

The importance of R6 lies in its implications for harvest timing and crop management. Understanding when the corn reaches this stage is essential for determining when to begin drying and harvesting the crop to minimize losses due to potential weather damage or field conditions.

The other stages represent different points in the corn's reproductive cycle. The dough stage (R4) refers to the period when the kernels are still developing and have not yet reached maturity, while R5 (grain fill) signifies that the kernels are filling and maturing but are not yet physiologically mature. R7 indicates that the corn is harvest ripe, meaning it has dried down sufficiently for harvesting, but it occurs after physiological maturity has been reached.