EFFECTS OF 10- AND 20-HOUR PHOTOPERIOD TREATMENTS AT 20 AND 30 C ON RATE OF DEVELOPMENT OF A SINGLE-CROSS MAIZE (ZEA MAYS) HYBRID

Abstract

A single-cross maize (Zea mays L.) hybrid was grown under two photoperiods (10 and 20 h) at two constant temperatures (20 and 30 C). Rate of development was characterized by the number of days from planting to tassel initiation, tassel initiation to silking, and silking to maturity. Long photoperiod and low temperature independently increased the number of days between planting and tassel initiation. The interval between tassel initiation and silking was not affected by photoperiod, but was increased significantly by the low temperature treatment. During the grain filling period (silking to maturity), temperature had the principal effect, but a photoperiod by temperature interaction did occur. Although plants grown at 20 C required more days to reach maturity than those grown at 30 C, the filling period at 20 C was shorter under the 10-h photoperiod than under the 20-h photoperiod, but at 30 C, the 10-h photoperiod treatment had the longer filling period. The delay in development at the low temperature, although apparent at all three stages of development, was not of the same magnitude. When the delay in development at 20 C is expressed as a percent of time required at 30 C, the 20 C treatment took 28% longer between planting and tassel initiation than the 30 C treatment. The corresponding figures for days between tassel initiation and silking and between silking and maturity were 58 and 46%, respectively.