The fill period in Cuzco flour corn

It has been an item of discussion, because of the singular kernel size of this unique land race, as to whether this variety ever forms black layer, if good cultural conditions are maintained. It is said that in its native habitat in Peru's Urubamba Valley the ear-shanks are broken down by hand to terminate filling. Until this past season, moreover, we have never seen BL formation except by the intervention of an outside condition to end the growing season. However, in 1985, we were able to plant on March 15. First silks emerged by June 6. Black layer could generally be found in the population on Nov. 20, on plants that were untouched by stalk rot, and were still green and more or less succulent. Temperatures were above average for the Salinas Valley. Under these conditions, then, the filling period for Cuzco, as indicated by BL formation, was about 150 days, or about 21/2 times the normal 60 day period for cornbelt hybrids.

D. L. Shaver

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