Genetic variation of maize responses to low temperatures in controlled conditions

Eighteen genetically-diverse maize hybrids (Zea mays, dent lines crossed to a flint inbred-line) were cultivated in a growth-chamber at optimal temperature (20°C) for three weeks. They were then submitted to three successive steps of decreasing temperature ( 16, 13 and 8.5°C). Each step lasted two days. Samples were taken on the youngest ligulated leaf (fourth or fifth leaf) at the end of the period at 20°C and at the end of each temperature step. Three replicates per genotype/ temperature combination were analyzed. Each replicate was made up of the mix of leaf samples from different plants.