Second and third growth period responses of Picea abies families to first growth period photoperiodic, light intensity and temperature treatments.

Abstract

Seedlings of (L.) H. Karst. full-sib families of contrasting origins were cultivated in a phytotron under different photoperiodic, light-intensity and temperature treatments during their first growth period. The effects of the treatments on juvenile growth traits – whether enhanced or delayed maturation was induces – were observed during the two subsequent growth periods. The following hypotheses were tested: (A) Enhanced maturation can be induced in the first growth period from sowing with (i) a long period of continuous light during active growth (24 weeks vs. 8 weeks); (ii) a shorter night during bud maturation (12 h vs. 16 h); high temperature (25°C vs. 20°C) during (iii) active growth, growth cessation and bud maturation; and during (iv) the latter part of growth cessation and bud maturation only. (B) Delayed maturation can be induced after (i) low light intensity during growth cessation and bud maturation (114 μmol m s vs. 340 μmol m s; low temperature (15°C vs. 20°C) during (ii) active growth, growth cessation and bud maturation; and during (iii) the latter part of growth cessation and bud maturation only. Picea abies-2-1-2-1)