Effects of Photoperiod and Temperatures on the Duration of Vegetative Growth in Maize1

Abstract

One objective of this study was to identify parental genotypes to be used in subsequent research into the inheritance of sensitivity to photoperiod in maize (Zea mays L.). Seventy inbreds were surveyed for their maturity responses under two photoperiods in a phytotron greenhouse. For short‐day maturity, a range was observed from 10.0 leaves for C3 to 23.0 leaves for Tx601. For photosensitivity (difference between long‐day and short‐day maturity), the range extended from 0.0 leaves for B14A to 8.5 leaves for CM103. The correlation between short‐day maturity, and photosensitivity across all entries was significantly positive, but among inbreds exhibiting moderate or late short day maturity, a large range in photosensitivity occurred. The maturity responses of seven inbreds were further examined in growth chambers primarily to study photoperiod ✕ temperature interactions and to compare two measures of maturity in maize. Based on days to tassel initiation (DTI) and particularly total leaf number (TLN), the effect of photoperiod was considerably greater than that of temperature. Photoperiod ✕ temperature interactions were significant only for DTI. Total leaf number (TLN) was concluded to be better than DTI for measuring effects of photoperiod upon the duration of vegetative growth in maize. Several other results with important implications for subsequent research on the inheritance of photosensitivity in maize are discussed.