Thermo- and photoperiodic influence on the variation in juvenile growth in open pollinated Carpinus betulus L. families

Abstract

The genetic variation in juvenile growth characters in seedlings of open pollinated Carpinus betulus L. families was studied in different thermo- and photoperiods in the Stockholm phytotron. Six or four families from each of two populations–Bern lat. 47oN and Bialowieza lat. 54oN–were included. Both the thermo-and photoperiods had a strong effect on plant height. The tallest plants were assessed in the high night temperature regime as well as in the photoperiod with the shortest night length. The thermoperiod also affected the growth rhythm characters. Growth cessation occurred earlier and bud break later in the material from the high night temperature regime. There was no effect of population in the thermo- or photoperiodic experiments. This might be attributed to the southern origin of the two populations. The effect of family variation within populations was always larger than the population effect, but only significant for two growth rhythm characters and for plant height in the photoperiodic experiment. The most striking feature of this study was the significant interaction effect between treatment and family. This complicates the selection of genotypes adapted to different climatic conditions. A larger sample ought to be studied before an applied selection programme can be designed.