The open-pollinated corn (Zea mays L.) cult Gaspé Flint and three hybrids, Guelph GX122, Harrow 691, and Pioneer X306, were selected to examine the effects of photoperiod and temperature on the number of days to tassel initiation. The range of maturity of this material varied from extremely early to subtropical. The experiments, conducted in growth cabinets, examined photoperiods of from 10 to 20 h in 21/2-h increments. Constant day–night temperatures examined were 20, 25, and 30 C. Photoperiod and temperature affected number of days to tassel initiation. The response was not consistent for each genotype. As daylength increased from 10 to 20 h all but the earliest genotype, Gaspé Flint, took longer to reach tassel initiation. The latest hybrid, Pioneer X306, was affected relatively more by photoperiod. The delay in tassel initiation with longer photoperiods was apparent at all temperatures; however, the magnitude of the response was less at the high temperature. With longer photoperiods, there was an increase in the amount of vegetative growth and development prior to tassel initiation. This was apparent from the greater number of emerged leaves, the longer stem length, and the greater plant dry weight at tassel initiation.
Photosynthetically active radiation and root-zone temperature effects on high-tunnel primocane red raspberry growth and development