Phytotron ecology of mutant genes

In this paper two eceriferum mutations (cer‐i 16 and cer‐c 36 ) were analysed in the Stockholm phytotron with regard to a series of quantitative traits, both in the heterozygous and the homozygous state. The cer‐i 16 homozygote showed an evident average superiority to the Bonus parent at 20 hours photoperiod, was superior, equal or inferior at 16 hours, and mostly inferior at 12 hours. The heterozygote was generally intermediate to both parents, whether it was superior to Bonus or inferior. A few cases of overdominance occurred. Throughout, the mutant homozygote of cer‐c 36 was inferior to Bonus in generative traits in the three photoperiods applied (24, 20 and 16 hours) but less inferior in semigenerative and vegetative traits. The mutant heterozygote was superior, equal or slightly inferior to the Bonus parent. Overdominance was commoner in the heterozygote of the “destructive” mutation cer‐c 36 than in that of the partially superior mutation cer‐i 16 .