Responses of Early Corn Inbreds to Photoperiod1

Abstract

Twelve early‐maturing inbred corn (Zea mats L.) lines were grown in controlled environments at photoperiods of 14, 16, 18, 19, 20, 21, 22, 23, or 24 hours. Days from emergence to anthesis increased as photoperiod increased for 10 of the 12 inbreds. The photoperiod response of the inbreds was adequately described by a three‐line model previously used for other plant species. Genotypic variability for the photoperiod response was identified.The basic vegetative phase, which is the time from emergence to anthesls in optimal photoperiod conditions, ranged from 37 to 57 days. The photoperlod sensitivity, expressed in days delay per hour increase of photoperiod, ranged from 0 to 2.5. The maximum optimal photoperiod, which is the longest photoperiod at which no photoperiod‐induced delay in anthesls is observed, ranged from 14 to 24 hours, and the critical photoperiod, above which no further delay in anthesis occurs, ranged from 21 to 24 hours. The photoperiod‐induced phase varied from 0 to greater than 17 days. A lack of correlation between components of the photoperiod response suggests independent regulation of these components.